patient-specific orthopedic implants and models

专利摘要:
patient-specific implants and orthopedic models patient-specific knee implant (1st) includes a femoral component (20) and a tibial tray component (30) and is designed based on specific patient data. a surface facing the internal bone (40) of the femoral component (20) conforms to the corresponding surface of the femoral condyle. alternatively, it can conform to one or more bone cuts optimized in the femoral condyle. however, the external articular surface (50) of the component (20) is intensified to incorporate a smooth surface having an almost constant radius in the coronal plane. the corresponding articular surface (70) of the tibial tray (30) has a surface contour in the coronal plane that is combined with the external articular surface (50). in certain embodiments, the articular surface (50) of the component (20) incorporates a sagittal curvature that positively matches the patient's existing or healthy sagittal radius.
公开号:BR112012008058B1
申请号:R112012008058
申请日:2010-08-26
公开日:2020-01-14
发明作者:Steines Daniel；Slamin John；Lang Philipp；Fitz Wolfgang
申请人:Conformis Inc；
IPC主号:

专利说明:

Invention Patent Descriptive Report for IMPLANTS
AND PATIENT-SPECIFIC ORTHOPEDIC MODELS.
CROSS REFERENCE TO RELATED REQUESTS
This claim claims the benefit of: US 61 / 275,174, filed on August 26, 2009, entitled Patient Specific Orthopedic Implants and Models; US 61 / 280,493, filed on November 4, 2009, entitled Patient Adapted and Improved Orthopedic Implants, Designs and Related Tools; US 61 / 284,458, filed December 18, 2009, entitled Patient Adapted and Improved Orthopedic Implants, Designs and Related Tools; US 61 / 339,766, filed March 9, 2010, entitled Patient Adapted and Improved Orthopedic Implants, Designs and Related Tools; PCT / US2010 / 025459, filed on February 25, 2010, entitled Patient-Adapted And Improved Orthopedic Implants, Designs And Related Tools; and PCT / US2010 / 039587, filed on June 23, 2010, entitled Patient-Adapted And Improved Articular Implants, Designs And Related Guide Tools.
Each of the requests described above is incorporated herein by reference in its entirety.
TECHNICAL FIELD
The invention relates to the creation of specific orthopedic implants and devices for the patient, as well as mathematical drawings and models of joints, especially human joints, based on data, such as image data, representing an existing joint. BACKGROUND
Generally, a diseased, damaged or defective joint, such as a joint with osteoarthritis, has been recovered using standard specific implants and other surgical devices. Only recently has the concept of patient-specific specific implants for an individual patient joint become available. Such patient-specific implants, such as iForma®, iUni® and iDuo®, offer advantages over the traditional several-size-fits-all approach as a better fit, movement
2/103 more natural, reduction in the amount of bone removed during surgery and a less invasive procedure. Said patient-specific implants are usually created from images of the patient's joint. Based on the images, the patient-specific implant can be created both to include surfaces that fit with existing surfaces in the joint as well as to include surfaces that approach an ideal and / or healthy surface that does not exist in the patient before any procedure .
SUMMARY
The present invention provides methods and devices for creating a desired model of a joint or parts or surfaces of a joint based on data derived from the existing joint. The existing joint data, for example, data generated from an image of the joint as an MRI or CT scan, is processed to generate a varied or corrected version of the joint or parts of the joint or surfaces within the joint. For example, the data can also be used to create a model that can be used to analyze the patient's joint and to design and evaluate a course of corrective action. The data and / or model can also be used to design an implant component containing one or more aspects specific to the patient, such as a surface or curvature.
In one aspect, some modalities provide implant components containing an internal surface that faces the bone designed to fit negatively on a bone surface. In certain embodiments, an external surface that faces the articulation of a first component of the implant is designed to and / or, at least in part of the component, to fit negatively on an external surface that faces the articulation of a second component of the implant. When creating component surfaces that negatively fit into a hinge interface, the opposing surfaces may not be anatomically shaped or close to the anatomical shape, but, instead, they can be negatively or almost negatively interlocked. This can have several advantages,
3/103 as reducing implant and joint wear and promoting more predictable joint movement.
In another aspect, some modalities provide implant components containing one or more patient-specific curvatures or radii in one dimension, and one or more standard or projected curvatures or radii in a second dimension.
In another aspect, methods of designing, selecting, manufacturing and implanting patient-specific implant components are provided.
It should be understood that the characteristics of the various modalities described here are not mutually exclusive and can exist in various combinations and permutations.
BRIEF DESCRIPTION OF THE DRAWINGS
What is mentioned above and other objects, aspects, characteristics and advantages of the modalities will become more apparent and can be better understood by consulting the following description, taken in conjunction with the attached drawings, in which:
FIGS. 1A-1C each shows a schematic diagram of an exemplary embodiment;
FIGS. 2A-2C depict drawings of implant components that have six bone cuts (FIG. 2A), seven bone cuts (FIG. 2B), and three bone cuts being a curvilinear bone cut (FIG. 2C);
FIG. 3A is a photograph showing an exemplary knee replacement using a patient-specific bicompartmental device and a patient-specific unicompartmental device; FIGS. 3B and 3C are x-ray images showing the device of FIG. 3A in the coronal plane and in the sagittal plane, respectively;
FIGS. 4A-4E show an exemplary design of a two-piece implant component;
FIG. 5A is a drawing of a cross-sectional view of an end of a femur with an osteophyte; FIG. 5B is a drawing of the end of the femur of FIG. 5A with an osteophyte virtually removed;
4/103
FIG. 5C is a drawing of the femur end of FIG. 5B with the osteophyte virtually removed and showing a cross-sectional view of an implant designed to mold to the femur with the osteophyte removed; FIG.5D is a drawing of the end of the femur of FIG. 5A and shows the cross-sectional view of an implant designed to mold to the femur with the osteophyte intact;
FIG. 6A is a cross-sectional view of the end of a femur with a subchondral void in the bone; FIG. 6B is a drawing of the end of the femur of FIG. 6A with a vacuum virtually removed; FIG. 6C is a drawing of the femur end of FIG. 6B with the void virtually removed and showing the cross-sectional view of an implant designed to mold to the femur with the void removed; FIG. 6D is a drawing of the femur end of FIG. 6A and showing the cross-sectional view of an implant designed to mold to the femur with the void intact;
FIGS. 6-1 - 6-7G illustrate steps in virtual limb alignment;
FIG. 7 is an example of an implant component showing the intersection of bone cuts on the internal surface that faces the implant bone;
FIG. 7-1 illustrates a computer model of a distal femur containing bone sections optimized for a pre-primary implant superimposed with a traditional primary implant (shown in outline);
FIGS. 7-2A and 7-2B schematically show a traditional implant component that displaces the joint line
FIG. 7-3 schematically shows a patient-specific implant component in which the existing or natural joint line is retained;
FIG. 7-4 describes an implant or implant design that includes a distal linear cut, a linear anterior cut, a linear posterior cut, and curvilinear chamfer cuts;
FIGS. 7-5A and 7-5B schematically show a component
5/103 patient-specific implant designed to substantially fit positively with the existing or natural joint gap of the patient;
FIGS. 7-6A - 7-6K show implant components with 5 exemplary aspects that can be included in a library.
FIG. 8 shows a coronal view of the patient's femoral bone and, in dotted lines, standard cuts of the bone made with a traditional total knee implant;
FIGS. 8-1A and 8-1B show the surfaces that carry the load of a femoral implant component in a coronal view (FIG. 8-1 A) and in a sagittal view (FIG. 8-1B);
FIGS. 8-2A and 8-2B show cross sections of a coronal view of two sections of the femoral condyle of a femoral component; FIG. 82C shows thicker material in a tibial implant component that is associated with the design of the sagittal curve or j of the femoral component to be tilted;
FIG. 8-3A - 8-3E show various aspects of the femoral component design approach;
FIG. 9A and FIG. 9B are schematic axial views of a femur and 20 patella; FIG. 9-1A - 9-1C show three different bone cuts for a femoral component;
FIG. 10 is a schematic sagittal view of a femur with indicated facet cuts;
FIGS. 11A and 11B show pockets of bone cement in an embodiment of an implant component (FIG. 11A) and in a traditional component (FIG. 11B);
FIGS. 11-1A and 11-1B show exemplary patella implant designs
FIG. 11-2 shows a patellar implant component containing an elongated shape;
FIGS. 12A and 12B show tibial and mediatic unicompartmental cuts and side components with and without a layer of polyethylene with
6/103 having different heights in relation to the tibial plateau; FIGS. 12C - 12E describe additional considerations of tibial implant designs;
FIG. 13A shows six exemplary tool tips and a polyethylene insert in cross section in the coronal view, the tool tips being used to generate a polyethylene insert containing a desired coronal curvature; FIG. 13B shows a sagittal view of two exemplary tools sweeping from different distances in a polyethylene insert to create different sagittal curvatures in the polyethylene insert;
FIGS. 14A and 14B show a tibial implant design with a groove or stepped surface extending throughout the component,
FIG. Ex 1-1 is a flow chart describing an exemplary process for designing a specific implant for the patient, specifically a total knee implant;
FIGS. Ex 2-1A - Ex 2-9B show various aspects of two bone cutting design methods;
FIG. Ex 3-1 shows an exemplary design of an implant component modality containing seven cuts on the inner surface that faces the bone;
FIG. Ex 3-2A and FIG. 3-2B are sagittal views of exemplary drawings of anterior and posterior femoral bone sections, respectively, which corresponds to the interior surface that faces the bone of the virtual model shown in FIG. Ex 3-1;
FIG. Ex 3-3 shows an exemplary drawing of an implant component containing seven sections of the inner surface that faces the bone and containing cement cutouts and pins with particular dimensions;
FIG. Ex 3-4A and FIG. Ex 3-4B show virtual models of bone cuts and corresponding bone volume for a model containing five bone cuts for the articular femoral surface (FIG. Ex 3-4A) and for a model containing seven bone cuts for the articular femoral surface (FIG. Ex 3-4B);
FIG. Ex 3-5A and FIG. Ex 3-5B show virtual models of bone cuts and corresponding bone volume for a model containing
7/103 five, non-flexed bone sections for the articular femoral surface (FIG. Ex 3-5A) and for a model containing five flexed bone sections for the articular femoral surface (FIG. Ex 3-5B);
FIGS. Ex 3-6A - Ex 3-6D shows exemplary virtual models of overlapping bone cuts (in broken lines) with the traditional implant format;
FIG. Ex 4-1A - Ex 4-1F shows several aspects of a knee implant, including a femoral component and a patella component, with a region of cut scheme material highlighted in red in certain figures;
FIGS. Ex 5-1A - Ex 5-7B shows several aspects of a set of templates to guide the specific cuts of bones in the patient in a first femur technique;
FIGS. Ex 6-1 - Ex 6-4 shows several aspects of a set of templates to guide the patient's specific bone cuts in a technique first on the tibia;
FIGS. Ex 7-1A - Ex 7-5 shows several aspects of a tibial implant design and cutting technique;
FIGS. Ex 8-1A - Ex 8-3E shows various aspects of tibial tray and insert designs;
FIGS. Ex 9-1A - Ex 9-11 shows several aspects of a finite element analysis (FEA) conducted on three variations of a femoral implant component;
FIG. Ex 10-1A is a schematic front view of a knee implant;
FIG. Ex 10-1B is the schematic cross-sectional view in the coronal plane of a femoral component of the implant of FIG. Ex 10-1A,
FIGS. Ex 11-1 - Ex 11-7C illustrates several aspects of a design for a tibial implant component;
FIGS. Ex 12-1A and 12-1B illustrate a computer model of a distal femur with posterior and anterior cut lines;
FIGS. Ex 12-2A - Ex 12-2C illustrate a computer model
8/103 of a distal femur with a design for a curvilinear cut line for the medial condyle;
FIGS. Ex 12-3A- Ex 12-3C illustrate a computer model of a distal femur with a design for a curvilinear cut line for the 5 lateral condyle;
FIGS. Ex 12-4A- Ex 13-4C illustrate a computer model of a distal femur with a drawing for all cut lines and a drawing for the corresponding implant component;
FIGS. Ex 12-5A- Ex 12-5C illustrate models of a distal femur and templates for making curvilinear cuts;
FIGS. Ex 12-6A and Ex 12-6B illustrate models of a distal femur and an implant containing curvilinear cuts;
FIGS. Ex 13-1A and Ex 13-1B illustrate a drawing of a femoral implant including a single cut, on its internal surface that faces the bone;
FIGS. Ex 13-2A and Ex 13-2B illustrate a design of a femoral implant including no cut on its internal surface that faces the bone; and
FIG. Ex 13-2C illustrates a model of a femur and a femoral implant 20 designed to include no cut on its internal surface that faces the bone.
DETAILED DESCRIPTION
When a surgeon uses a specific traditional implant to replace the patient's joint, for example, a knee joint, 25 hip joint, or shoulder joint, certain spatial aspects of the implant typically do not match certain spatial aspects of the particular biological structures of the patients in the joint. These detachments cause various complications during and after surgery. For example, surgeons may need to extend the time of surgery and apply better assumptions and rules of the thumb during surgery to target disengagements. In addition, to improve the fit between a traditional implant and the patient's biological structures, surgeons typically
9/103 comes with substantial portions of the patients' articular bones so that the patient's articular surfaces conform to the standard shape of the surface that faces the bone of the traditional implant.
For the individual patient, complications associated with five sencaixes may include pain, discomfort, and an unnatural joint sensation, as well as an altered range of motion and an increased likelihood of implant failure. In addition, the substantial loss of bone portions associated with implantation of a traditional primary implant typically limits the patient to only a subsequent revision of the implant.
The present invention relates to patient-specific implants and methods for designing, producing and using them. Some modalities refer to the articular components of the implant containing one or more specific aspects for the patient adapted to a characteristic of the patient's biology, such as biological structure, alignment, kinematics, and / or soft tissue impositions. The one or more patient-specific aspects may include, but are not limited to, surfaces of the implant component, such as surface contours, angles or cuts of the bone, and dimensions of the implant component, such as thickness, width, or length. The patient-specific aspects of the implant component can be designed from patient-specific data to fit an existing feature of the patient's biology. Alternatively, patient-specific aspects of the implant component can be designed for the patient from patient-specific data to improve an existing feature of the patient's biology.
Implants and methods of certain modalities can be applied to any joint including, without limitation, spine, spinal joints, an intervertebral disc, a facet joint, the shoulder joint, an elbow, a wrist, a hand, a finger joint, 30 a hip, knee, ankle, foot, or toe joint. In addition, various modalities can be adapted and applied to the implant instrumentation used during surgical procedures or other procedures, and to methods of using the various patient-specific implants, instruments, and other devices.
In certain respects, implants and methods include a patient-specific internal surface to connect to a patient's bone resection. In particular, patient-specific data collected before the operation is used to determine one or more patient-specific bone cuts for a patient's bone and for the inner surface that faces the bone of an implant component. Bone cuts are optimized (that is, designed for the patient) to maximize one or more parameters, such as: (1) deformity correction and limb alignment (2) maximum preservation of bone, cartilage or ligaments, (3) preservation and / or optimization of other characteristics of the patient's biology, such as trochlea and trochlear shape, (4) restoration and / or optimization of joint kinematics, and / or (5) restoration or optimization of joint line location and / or width of the joint gap. Based on optimized bone cuts, the internal surface of the implant that faces the bone is designed to, at least in part, negatively fit the shape of the bone cut. In addition, the external surface of the implant facing the joint can be designed to, at least in part, substantially negatively engage the cavity of the joint on the opposite surface. Thus, certain modalities are directed at implants and methods that address many of the problems associated with traditional implants, such as detachments between an implant and a patient's biological structure, and substantial bone removal that limits subsequent revisions after a traditional primary implant.
Certain modalities are aimed at patient-specific implants and implant designs applied as a pre-primary implant device, so that a subsequent replacement implant can be performed with a second (and, optionally, a third) pre implant device - patient-specific primer or with a traditional primary implant. Certain modalities are aimed at patient-specific implants and implant designs applied as an implant device
11/103 primary, so that a subsequent replacement implant can be performed with a traditional overhaul. Certain modalities are directed at patient-specific implants and implant designs applied as a revision implant device, so that a subsequent revision may be possible with a second patient-specific implant containing one or more aspects specific to the patient.
In certain respects, implants and methods may include one or more aspects specific to the patient and one or more standard aspects. For example, a curved surface of an implant component can include one or more dimensions or rays that are specific to the patient, and one or more dimensions or rays that are patterns. For example, in certain embodiments, a portion of the condyle of a femoral implant component and / or a corresponding groove on the supporting surface of a tibial implant component may include a patient-specific sagittal curvature or radius and a standard coronary curvature or radius . Patient-specific curvature or radii can be drawn from patient-specific data to adapt to an existing feature of the patient's biology or they can be designed for the patient from patient-specific data to improve an existing feature of the patient's biology . The standard curvature or radii include curvatures or radii used in implants for all, or a collection of patients.
Exemplary implant systems and patient-specific characteristics
Various types of implants and implant systems are contemplated here, including, but not limited to, knee joint implants, hip joint implants, and shoulder joint implants. In certain embodiments, an implant or implant system may include one, two, three, four or more components. An implant component can be designed and / or produced to include one or more patient-specific characteristics that substantially fit with one or more of the patient's biological structures, such as bone, cartilage, tendon or muscle. In addition, or alternatively, an implant component can be designed and / or produced to include one or more features
12/103 patient-specific characteristics that substantially fit one or more components of the implant. In addition, an implant component can be designed and / or produced to include one or more non-specific patient features that substantially fit with one or more implant components.
The term component of the implant as used here is used to include (i) one of two or more devices that work together on an implant or implant system, or (ii) a complete implant or implant or implant system, for example, in modalities in which an implant is a simple, unitary device. The term fits as used here is used to include one or both of a negative fit, as a convex surface fits a concave surface, and a positive fit, as one surface is identical to the other surface.
Three exemplary modalities of implants or implant components are schematically represented in FIGS. 1A - 1C. The dotted line over the figures represents an exemplary line of articulation. FIG. 1A shows an exemplary component of implant 100. Component 100 includes an inner surface that faces bone 102 and an outer surface that faces joint 104. The inner surface that faces bone 102 engages a first articular surface 110 of a first biological structure 112 at a first interface 114. The articular surface 110 can be a native surface or a cut surface. The external surface facing the joint 104 is opposed to a second joint surface 120 of a second biological structure 122 in an articulation interface 124. In certain embodiments, one or more characteristics of the implant component, for example, an ML, AP dimension , or Sl, a feature of the inner surface that faces the bone 102, and / or a feature of the outer surface that faces the joint 104, are adapted to the patient (i.e., include one or more specific characteristics of the patient and / or designed to the patient).
The implant modality shown in FIG. 1B includes two implant components 100, 100 '. Each implant component 100, 100 ’
13/103 includes an internal surface that faces bone 102, 102 'and an external surface that faces joint 104, 104'. The first internal surface that faces the bone 102, engages a first articular surface 110 of a first biological structure 112 at a first interface 114. The first articular surface 110 can be a native surface or a cut surface. The second bone-facing surface 102 'engages a second articular surface 120 of a second biological structure 122 and a second interface 114'. The second articular surface 120 can be a native surface or a cut surface. In addition, an outer surface that faces hinge 104 in the first component 100 is opposed to a second outer surface that faces hinge 104 'in the second component 100' at the hinge interface 124. In certain embodiments, one or more features of the component of the implant, for example, one or both of the inner surfaces that face the bones 102, 102 'and / or one or both of the outer surfaces that face the joints 104, 104', are adapted to the patient (i.e., include one or more features specific and / or designed for the patient).
The implant modality shown in FIG. 1C includes the two implant components 100, 100 ', the two biological structures 112, 122, the two interfaces 114, 114', and the hinge interface 124, as well as the corresponding surfaces described for the embodiment shown in FIG. 1B. However, FIG. 1C also includes structure 150, which can be a component of the implant in certain modalities or a biological structure in certain modalities. Thus, the presence of a third structural surface 150 in the joint creates a second joint interface 124 'and possibly a third 124 in addition to the joint interface 124. Alternatively, or in addition, the patient-adapted features described above for the components 100 and 100 ', components 100, 100 can include one or more features, such as surface features on additional hinge interfaces 124, 124, as well as other dimensions (for example, height, width, depth, contours, and other dimensions) that are adapted to the patient, in whole or in part. In addition
14/103 so, structure 150, when this is a component of the implant, can still have one or more characteristics adapted to the patient, such as one or more surfaces and dimensions adapted to the patient.
As mentioned above, specific traditional implants and implant components may have internal surfaces that face the bone that are a poor fit to the patient's biological structures. In addition, traditional products may have external surfaces that face the joint that weakly fit with the healthy or ideal patient's particular joint. Patient-specific implants and methods of some modalities that improve these deficiencies are described in more detail in the following two subsections, with respect to the surface that faces the bone and the surface that faces the joint of an implant component; however, the principles described here are applicable to any implant surface or implant component.
Surface that faces the bone of an implant component
In certain embodiments, the bone-facing surface of an implant component can be designed to substantially fit negatively to one or more surfaces of the bone. For example, in certain embodiments at least a portion of the surface that faces the bone of a patient-specific implant component can be designed to substantially fit negatively to the shape of the subchondral bone, cortical bone, endosteal bone, or bone marrow. A part of the implant can also be designed for regeneration, for example, by parts that negatively fit a surface that faces the bone of the implant component to the subchondral bone or cartilage.
In certain embodiments, the bone-facing surface of a patient-specific implant component includes bone cuts. For example, the surface facing the implant bone can be designed to substantially negatively fit one or more bone surfaces derived from one or more cuts to the bone. The surface that faces the implant bone can include any number of bone cuts, for example, two, three, four, less than five, five, more than five,
10-153 six, seven, eight, nine or more bone cuts. FIG. 2A depicts a drawing of a femoral implant component 100 containing six bone cuts. FIG. 2B describes a drawing of a femoral implant component 100 containing seven bone cuts.
In the figures, the six or seven respective bone cuts are identified by arrows on the inner surface that faces the bone 102 of the implant component 100. As shown by the implant drawings in the figures, each of the bone cuts on a surface that faces the bone can be substantially planar. However, in certain embodiments, one or more cuts of bone may be curvy. In certain embodiments, the entire surface that faces the bone can be substantially curvilinear. FIG. 2C describes a design of a femoral implant component 100 containing three bone cuts, one of which is a curvilinear bone cut.
In certain embodiments, the thicknesses, surfaces and / or cuts of bones in the corresponding sections of an implant component may be different. Specifically, one or more of the thicknesses, section volumes, bone cut angles, bone cut surface areas, bone cut curvatures, bone cut numbers, dowel replacement, dowel angles, and other characteristics can vary between two or more corresponding sections of an implant component. For example, the corresponding medial and lateral sections identified as X and X 'of the femoral implant design in FIG. 2A are shown to include different thicknesses, section volumes, bone cutting angles, and bone cutting surface areas.
In certain embodiments, the bone-facing surface of the implant component may include one or more parts designed to engage the regenerated bone, for example, containing a surface that negatively fits the uncut subchondral bone or cartilage, and one or more parts designed to engage the cut bone, for example, having a surface that negatively fits a cut subchondral bone.
Surface facing the articulation of an implant component
10/163
The external surface that faces the joint of a patient-specific implant component can be designed to fit the patient's articular cartilage shape. For example, this can substantially fit positively to the normal or healthy cartilage shape in the joint that the component replaces; or it can substantially fit negatively to the shape of the cartilage on the opposite joint surface in the joint. Corrections can be made to the diseased cartilage shape to restore a normal or close to normal cartilage shape that can be incorporated into the shape of the surface that faces the component's joint. These corrections can be implemented and, optionally, tested in two-dimensional and three-dimensional virtual models. Corrections and tests may include kinematic analysis, as described below.
In certain embodiments, the surface that faces the joint of the patient-specific implant component can be designed to positively fit the shape of the subchondral bone. This can include the shape of normal and / or diseased subchondral bone. Corrections can be made to the shape of the subchondral bone to restore a normal or close to normal joint shape that can be incorporated into the shape of the surface that faces the component's joint. A standard thickness can be added to a surface that faces the joint. Alternatively, a variable thickness can be applied to the component. The variable thickness can be selected to reflect the patient's actual or healthy cartilage thickness, for example, as measured on the individual patient or selected from a standard reference database.
In certain embodiments, the surface that faces the joint of the patient-specific implant component can be designed to positively fit a standard shape. For example, the standard shape can have a fixed radius in one or more directions, or it can have variable radii in one or more directions. The implant component can have a constant thickness in selected areas or it can have a
17/103 variable weight in selected areas. The standard shape of the surface facing the component joint may include, at least in part, the shape of normal and / or diseased subchondral bone or cartilage. Corrections can be made to the shape of the subchondral bone or cartilage to restore a normal or close to normal joint shape that can then be incorporated into the shape of the surface that faces the component's joint. A standard thickness can be added to the surface that faces the component joint, or alternatively, a variable thickness can be applied to the implant component. The variable thickness can be selected to reflect cartilage thickness, in at least part of the component, for example, as measured on the individual patient or selected from a standard reference database.
Certain embodiments, such as those shown schematically in FIG. 1B and FIG. 1C, include, in addition to a first component of the implant, a second component of the implant containing a surface that faces the joint. In said embodiments, the surface that faces the joint in the second component can be designed, at least for a part of its surface, to negatively fit the surface that faces the joint of the first component. Designing a surface that faces the joint of the second component as a negative fit of the surface that faces the joint of the first component can help reduce implant wear. Thus, in some modalities, the surfaces that face the joints are not anatomical or close to anatomical in shape, but on the contrary they fit negatively or almost fit negatively on the surface that faces the bone of a component in opposition to the joint.
Thus, when the surface that faces the joint of the first component is designed to positively fit at least part of the patient's cartilage shape, the surface that faces the joint as opposed to the second component is, at least in part, a negative fit. cartilage shape. When the surface that faces the joint of the first component is designed to fit positively
18/103 At least part of the shape of the patient's subchondral bone, the surface facing the joint in opposition to the second component is, at least in part, a negative fit of the shape of the subchondral bone. When the surface that faces the joint of the first component is designed to positively fit at least part of the shape of the patient's cortical bone, the surface that faces the joint in opposition to the second component is, at least in part, a negative fit of the cortical bone shape. When the surface that faces the joint of the first component is designed to positively fit at least part of the shape of the patient's endosteal bone, the surface that faces the joint in opposition to the second component is, at least in part, a negative fit of the endosteal bone shape. When the surface that faces the joint of the first component is designed to positively fit at least part of the shape of the patient's bone marrow, the surface that faces the joint in opposition to the second component is, at least in part, a negative fit of the bone marrow shape.
The surface facing the joint in opposition to the second component can be substantially negatively engaged with the surface facing the joint of the first component in one plane or dimension, in two planes or dimensions, in three planes or dimensions, or in several planes or dimensions. For example, the surface facing the joint in opposition to the second component can be substantially negatively engaged with the surface facing the joint of the first component in the coronal plane only, in the sagittal plane only, or in both the coronal and sagittal planes.
By creating the contour that fits negatively on the surface facing the joint as opposed to the second component, geometric considerations can improve the wear between the first and second components. For example, the rays on the surface facing the joint in opposition to the second component can be selected to be slightly larger in one or more dimensions than the rays on the surface
19/103 that faces the articulation of the first component.
The surface that faces the bone as opposed to the second component itself can be designed to negatively fit, at least in part, to the shape of the articular cartilage, subchondral bone, cortical bone, endosteal bone or bone marrow. It can have any of the above characteristics for the surface that faces the bone of the first component, as containing one or more patient-specific bone cuts.
Many combinations of surfaces that face the bone and articulation of the components on the first and second articular surfaces are possible. Table 1 provides illustrative combinations that can be used.
TABLE 1: Illustrative Combinations of Components of the
1 , ^the compo- ^the compo- 1 1 2 2 _ηοη ^the com- ponent * _ο su- compo- nent component su- component _rt ___ '.. Ω norfícip Aue te surface co jerfície surface cuts the ãceia osso______
^Example:: ____ ³ êmur bond least one bone cutting jerfície that the articulation ãceia
^Example:: _____ êmur
Bone cuts cartilage
Example: -êmur
Yes surface that faces the joint
Example: Tibia
At least one bone cut
Cartilage
Yes
At least one bone cut
Cartilage
Yes
Fitting negaivo of ^the component 1 Pekah the joint (as opposed cartilage) fitting ^the first negative component Pekah the joint (as opposed cartilage) 1 Negative Fitting component Pekah joint (as opposed cartilage) that Pekah the osso__
Example:
íbia __________ => link minus a bone cut makes up bone cuts
Example: tibia
Yes
Subchondral bone
Cartilage (same as, for example, bia) laθ 'tí
Optional
Optional
10/20
1 ^the surface component that faces the bone 1 ^the surface component that accepts the joint ° component of bone cuts _2nd surface component that faces the joint 2nd component surface that faces the bone Two component bone cuts At least one bone cut Subchondral bone Yes Fitting denies: 1 ivo of ^the component Pekah the subchondral bone joint in opposition) ³ link minus a bone cut Yes At least one bone cut Subchondral bone Yes 1 Attach ^the negative component Pekah the joint (as opposed subchondral bone) Subchondral bone Optional At least one bone cut Subchondral bone Yes 1 Attach ^the negative component Pekah the joint (as opposed subchondral bone) Cartilage (same side, for example, tibia) Optional Subchondral bone Cartilage Optional 1 Attach ^the negative component Pekah the joint (cartilage opposite) At least one bone cut Yes Subchondral bone Cartilage Optional 1 Attach ^the negative component Pekah the joint (cartilage opposite) Subchondral bone Optional Subchondral bone Cartilage Optional Negative fit of the 1 ⁰ component that faces the joint (opposite cartilage) Cartilage (same side, eg tibia) Optional
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1 ^the surface component that faces the bone 1 ^the surface component that sharpens the joint 1 ^the bone cuts commander 2nd surface component that faces the joint 2nd component surface that faces the bone 2nd component of bone cuts Subchondral bone Subchondral bone Optional 1 Attach ^the negative component Pekah the joint (as opposed subchondral bone) At least one bone cut Yes Subchondral bone Subchondral bone Optional 1 Attach ^the negative component Pekah the joint (as opposed subchondral bone) Subchondral bone Optional Subchondral bone Subchondral bone Optional 1 Attach ^the negative component Pekah the joint (as opposed subchondral bone) Cartilage (same side, for example, tibia) Optional Subchondral bone Standard / Model Optional 1 Attach ^the negative component that standard joint Pekah At least one bone cut Yes Subchondral bone Standard / Model Optional 1 Attach ^the negative component that standard joint Pekah Subchondral bone Optional Subchondral bone Standard / Model Optional 1 Attach ^the negative component that standard joint Pekah Cartilage (same side, for example, tibia) Optional1
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1 ^the surface component that faces the bone 1 ^the surface component that faces the joint 1 ^the component of bone cuts 2nd surface component that faces the joint 2 ^the surface component that faces the bone ^The second com- nenie cuts bone the and of Subchondral bone Subchondral bone Optional Does not fit on standard surface At least one bone cut Yes Subchondral bone Cartilage Optional Does not fit on standard surface At least one bone cut Yes
Multicomponent implants and implant systems
The disclosed implants and implant systems can include any number of patient-specific implant components and any number of non-patient-specific implant components. An exemplary implant or implant system is described in FIGS. 3A 30. Specifically, FIG. 3A shows a photograph of a patient-specific total knee replacement implant system that includes a patient-specific bicompartmental implant component 300 and a patient-specific unicompartmental implant component 310. Both components are patient specific on both its bones-facing surfaces and on its joints-facing surfaces. FIGS. 3B and 3C are X-ray images showing the implant of FIG. 3A in the coronal plane (FIG. 3B) and the sagittal plane (FIG. 3C).
In certain embodiments, implants and implant systems may include a combination of implant components, such as a traditional unicompartmental device with a device specific for the bicompartmental patient or a combination of a unicompartmental device specific for the patient with a standard bicompartmental device. Said implant combinations allow for flexible design of an implant or implant system that includes both standard and patient-specific characteristics and components. This flexibility and level of patient specificity allow for several optimizations, such as retention of all ligaments and / or restoration of normal or close to normal kinematics.
In certain embodiments, a component of the implant is designed
23/103 and installed as one or more parts. For example, FIGS. 4A-4E show an exemplary design of a femoral implant component that can be installed in two pieces.
The modalities described here can be applied to partial or total joint replacement systems. Bone cuts or changes to a joint surface described here can be applied to part of a joint surface, a complete joint surface, or multiple joint surfaces. Thus, for example, certain modalities include partial knee replacement, such as patellofemoral knee replacements, unicompartmental knee replacements, bicompartmental replacements and total knee replacements. In addition, the modalities described here can be applied to hemiarthroplasty systems, for example, femoral hemiarthroplasty on the hip joint, cup arthroplasty on the hip joint, or tibial hemiarthroplasty.
Collection and use of patient data to design and create a patient-specific implant
As mentioned above, in some modalities the implants are designed and created using specific patient data that are collected preoperatively. Specific patient data may include points, surfaces, and / or landmarks, collectively referred to here as reference points. In certain embodiments, reference points are selected and used to derive a varied or altered surface, such as, without limitation, an ideal surface or structure. For example, landmarks can be used to create patient-specific implants containing at least one patient-specific surface, dimension or aspect. Alternatively, or in addition, landmarks can be used to create at least one surface, dimension or aspect of an implant optimized for the patient.
Sets of landmarks can be grouped together to form reference structures used to create a joint model and / or implant design. The implant surfaces designed can be derived from simple reference points, triangles,
24/103 polygons, or more complex surfaces or models of the joint material, such as, for example, articular cartilage, subchondral bone, cortical bone, endosteal bone or bone marrow. Various reference points and reference structures can be selected and manipulated to derive a varied or altered surface, such as, without limitation, an ideal surface or structure.
Landmarks can be located on or in the joint that will receive the patient-specific implant. For example, landmarks can include weight bearing surfaces or locations on or over the joint, a cortex in the joint, or an endosteal surface of the joint. Landmarks can also include surfaces or locations outside, but related to, the joint. Specifically, landmarks can include surfaces or locations functionally related to the joint. For example, in modalities aimed at the knee joint, landmarks may include one or more locations that range from the hip down to the ankle or foot. Landmarks can also include surfaces or locations homologous to the joint receiving the implant. For example, in modalities aimed at a knee, hip, or shoulder joint, landmarks may include one or more surfaces or locations of the corresponding knee, hip, or shoulder joint.
2.1 Variations to biological surfaces in the joint
In certain embodiments, reference points can be processed using mathematical functions to derive corrected surfaces, which can represent an ideal or desired surface from which a specific implant for the patient can be designed. For example, one or more surfaces or dimensions of a biological structure can be modeled, altered, added, modified, deformed, eliminated, corrected and / or otherwise manipulated (collectively referred to here as variation of a surface or structure within the joint) .
The variation of the joint or parts of the joint may include, without limitation, variation of one or more of the external surfaces, surface
25/103 internal cies, surfaces that face the joint, uncut surfaces, cut surfaces, altered surfaces, and / or partial surfaces as well as osteophytes, subchondral cysts, geodes or areas of bone condensation, joint flattening, contour irregularity, and loss in a normal way. The surface or structure may be or reflect any surface or structure in the joint, including, without limitation, bone surfaces, ridges, plateaus, cartilage surfaces, ligament surfaces, or other surfaces or structures. The derived surface or structure may be an approximation of a healthy joint surface or structure or it may be another variation. The surface or structure can be made to include pathological changes in the joint. The surface or structure can also be made by means of which pathological changes in the joint are virtually removed in whole or in part.
Once one or more landmarks, structures, surfaces, models, or combinations of them have been selected or derived, the resulting shape can be varied, deformed or corrected. In some embodiments, the variation can be designed to derive an ideal implant shape. In an application of this modality, the preferred shape of the implant is similar to the patient's joint before he or she developed arthritis.
The variation may include additional changes to the joint, such as the virtual removal of osteophytes or the virtual construction of support structures that are actually beneficial for an end result for a patient.
2.1.1 Variations to target osteophytes
In the case of removal of osteophytes, the surface facing the implant bone is then derived after the osteophyte has been virtually removed. Alternatively, the osteophyte can be integrated into the shape of the surface that faces the implant bone. For example, FIGS. 5A-5D are drawings of the end of a femur 10 containing an osteophyte 20. During the development of an implant, the image can be transformed so that the osteophyte 20 is virtually removed as shown in FIG. 5B in the removed osteophyte 30 to produce, as shown in FIG. 5C, an im
26/103 plant 40 based on a smooth surface at the end of the femur 10. Alternatively, as shown in FIG. 5D, an implant 50 can be developed to conform to the shape of the osteophyte 20. In the case of additional construction or improved structure, the surface that faces the implant bone is then derived after the additional structure is modeled.
2.1.2 Variations to target subchondral voids
A subchondral void can be integrated into the shape of the surface that faces the implant bone. For example, FIGS. 6A-6D are drawings of the end of a femur 60 containing a subchondral void 70. During the development of an implant, the image can be transformed so that the void 70 is virtually removed as shown in FIG. 6B in the removed void 80 to produce, as shown in FIG. 6C, an implant 90 based on a smooth surface at the end of the femur 60. Alternatively, the implant 100 can be designed to conform to the shape of the void 70, as shown in FIG. 6D. Note that, while virtually conforming to the void 70, the implant 100 may practically not be able to be inserted into the void. Therefore, in an alternative modality, the implant can only be partially designed into a void in the bone.
2.1.3 Variations to address other defects or specific patient phenomena
In another embodiment, a correction may include the virtual removal of subchondral cysts. The surface facing the implant bone is then derived after the subchondral cyst is virtually removed.
In another embodiment, a correction may include virtual removal of joint defects. The surface that faces the implant bone is then derived after the joint defect has been virtually removed. In this modality, the defect can then be filled intraoperatively with bone cement, bone graft or other bone fillers. Alternatively, the joint defect may be integrated with the shape of the surface that faces the implant bone.
The variation may include the virtual removal of flattening of
27/103 a rounded articular surface. The surface facing the joint and / or that facing the implant bone can then be derived after the flattening has been virtually corrected. This correction can, for example, be designed to restore a format close to normal. Alternatively, the correction can be designed to establish a standard shape or surface. Alternatively, the flattening can be integrated into the shape of the surface that faces the implant bone. In this case, the surface that faces the joint of the joint implant can be designed to restore an anatomical shape close to normal, which reflects, for example, at least in part the shape of normal cartilage or subchondral bone.
Alternatively, it can be designed to establish a standard format.
2.2 Determine joint dimensions
In certain embodiments, an image test, for example, X-ray imaging, digital tomosynthesis, cone beam CT, spiral or non-spiral CT, isotropic or non-isotropic MRI, SPECT, PET, ultrasound, laser imaging, photo-acoustic image, is used to determine joint dimensions and / or shape in two or three dimensions. Determining joint dimensions and / or shape may include determining joint dimensions and / or shape for one or more of normal cartilage, diseased cartilage, a cartilage defect, an area of bare cartilage, subchondral bone, cortical bone, endosteal bone, bone marrow, a ligament, a ligament or ligament origin, meniscus, labrum, a joint capsule, or joint structures. Determining the dimensions may include determining the shape, curvature, size, area, thickness and / or volume.
2.2.1 Gap, sizing and library options
Using these joint dimensions and, optionally, other data, a patient-specific implant component can be designed and produced to have joint dimensions that fit the patient specifically. Alternatively, these patient-specific joint dimensions can be used to select an implant from a selection, for example, of small, medium implants, or
28/103 large, or gap implants, or an implant library. The selected gap implant or library implant is then adjusted to include specific patient characteristics.
2.3 Determine the alignment of the limb,
The proper function of the joint and limb depends on the alignment of the limb. For example, when repairing a knee joint with one or more knee implant components, the optimal functioning of the new knee depends on the correct alignment of the anatomical axes and / or lower extremity mechanisms. Thus, an important consideration _{10 in the} design and / or replacement of a natural joint with one or more implant components is the proper alignment of the limb or, when the malfunction of the joint contributes to misalignment, proper realignment of the limb.
Some modalities include collecting and using image test data to virtually determine on one or more planes one or more of the anatomical axes and a mechanical axis and the related misalignment of a patient's limb. The misalignment of a joint in relation to the axis can identify the degree of deformity, for example, varus or valgus deformity in the coronal plane or deformity of genu an20 tecurvatum or recurvatum in the sagittal plane. Then, one or more of the patient-specific implant components and / or implant procedure steps, such as bone resection, can be designed to help correct misalignment.
Imaging tests that can be used to virtually determine a patient axis and misalignment can include one or more of such images by X-rays, digital tomosynthesis, cone beam CT, spiral or non-spiral CT, isotropic MRI or not isotropic, SPECT, PET, ultrasound, laser imaging, and photoacoustic imaging, including studies using contrast agents. The data from these tests can be used to determine anatomical reference points or limb alignment, including alignment angles within the same joint or between different joints or to simulate normal limb alignment.
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Any anatomical feature related to misalignment can be selected and the image made. For example, in certain modalities, such as for a knee or hip implant, the imaging test may include data from at least one of, or several of, a hip joint, knee joint, and ankle joint. The image test can be obtained in a lying, prone, supinated or standing position. The imaging test can include the target joint, or the target joints and also the data selected by one or more contiguous joints.
Using image data, one or more axes, angles, mechanical or anatomical planes or combinations of them can be determined. In certain embodiments, said axes, angles, and / or planes may include, or be derived from, one or more of a Whiteside line, Blumensaat line, transepicondylar line, femoral axis line, femoral neck line, acetabular angle, lines tangent to the superior and inferior acetabular margins, lines tangent to the anterior or posterior acetabular margins, and femoral axis, tibial axis, transmaleolar axis, posterior condylar line, tangent to the trochlea of the knee joint, tangent to the medial or lateral patellar facet, tangent lines or perpendicular to the posterior medial and lateral condyles, tangent lines or perpendicular to the central load portion area of the medial and lateral femoral condyles, intersecting lines of the posterior medial and lateral condyles, for example, through their respective central points, tangent lines or perpendicular to the tibial tuberosity, vertical lines or at an angle to any of the lines mentioned above das, and / or lines tangent to or intersecting the cortical bone of any bone adjacent to or contained in a joint. In addition, estimating a mechanical axis, angle, or plane can also be performed using image data obtained through two or more joints, such as the knee joint and ankle joint, for example, using the femoral axis and a central point from another point on the ankle, as the point between the malleoli.
As an example, if knee or hip surgery is contemplated, imaging testing may include acquiring data through at least
30/103 one of, or several of, hip joint, knee joint or ankle joint. As another example, if knee joint surgery is contemplated, a mechanical axis can be determined. For example, the central point of the hip, knee and ankle can be determined. By connecting the central point of the hip with that of the ankle, a mechanical axis can be determined in the coronal plane. The knee position in relation to this mechanical axis may be a reflection of the degree of varus or valgus deformity. The same determinations can be made on the sagittal plane, for example, to determine the degree of genu antecurvatum or recurvatum. Similarly, any of these determinations can be made in any other desired plane, in two or three dimensions.
2.3.1 Virtual limb alignment to design an ear implant and implant procedure
From a three-dimensional perspective, the lowermost extremity of the body ideally functions within a single plane known as the anterior-posterior median plane (MAP plane) along the flexion-extension arc. To achieve this, the femoral head, the mechanical axis of the femur, the patellar juice, the intercondylar notch, the joint patellar crest, the tibia and the ankle remain within the MAP plane during the flexion-extension movement. During movement, the tibia rotates as the knee flexes and extends on the epicondylar axis, which is perpendicular to the MAP plane.
As shown in FIG. 6-1, the mechanical axis of a patient's lower extremity can be defined by the center of the hip 1902 (located on the 1930 head of the 1932 femur), the center of the knee 1904 (located on the notch where the 1934 tibial intercondylar tubercle meets the femur) and the center of the ankle 1906. In the figure, the long axis of the tibia 1936 is collinear with the mechanical axis of the lower end 1910. The anatomical axis 1920 aligns 5-7 degrees of compensation Θ of the mechanical axis in the direction of the valgus, or out. A variety of image sections can be taken from each joint, for example, on one or more of the 1950 knee joint, the 1952 hip joint, and the ankle joint, to determine the mechanical center point for each joint.
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In certain preferred embodiments, anatomical landmarks are used to virtually determine a patient's misalignment and the appropriate mechanical axis of his or her lower extremity. Based on the difference between the patient's misalignment and the appropriate mechanical axis, a knee implant and implant procedure is virtually designed to include implant dimensions and / or resection that substantially realigns the patient's limb to have an appropriate mechanical axis. The implant design process can include fabricating the implant (for example, using CAM software) and, optionally, the implant can be surgically implanted into the patient according to the virtually designed procedure.
In certain embodiments, an appropriate mechanical axis of the lower extremity patient, and the extent of misalignment of the extremity, is virtually determined using a computer aided design software program, such as SolidWorks software (Dassault Systèmes SolidWorks Corp., 300 Baker Avenue , Concord, MA 01742). Using the software, patient-specific information, for example, a collection of anatomical landmarks, is used to generate a virtual model that includes the patient's knee joint.
The virtual model can also include the reference points of the hip and / or ankle joints. Using the virtual model, a user can virtually determine the misalignment of and the mechanical axis of the patient's lower extremity by determining in the model the patient's tibial mechanical axis, femoral mechanical axis, and one or more planes of each axis. For example, the patient's tibial mechanical axis can be determined virtually in the model as a line connecting the center of the patient's ankle and the center of the patient's tibia. The patient's femoral mechanical axis can be determined virtually in the model as a line connecting the center of the patient's hip and the center of the patient's distal femur. The center of the patient's ankle, tibia, hip, and / or distal femur can be determined based on the patient's specific landmarks or anatomical landmarks used to generate the virtual model.
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Then, the user can virtually align the lower end by collinear alignment of the tibial and femoral mechanical axes. This collinear alignment can be achieved by adjusting the angle of the intersecting axes in the knee joint to zero. The axes can be axially aligned by aligning one or more planes common to both axes, such as the sagittal or coronal planes. FIGS. 6-2A - 6-2C each illustrates a model showing the existing misalignment of a lower extremity of the patient (gray and solid line) and the virtual alignment (white and dotted line) determined using the model.
Exemplary methods for determining the tibial mechanical axis, the femoral mechanical axis, and the sagittal and coronal planes for each axis are described in greater detail in the following subsections.
2.3.2 Tibial mechanical axis and sagittal and coronal planes
In certain embodiments, the tibial mechanical axis and the sagittal and coronal tibial planes are determined virtually using a model that includes the reference points of a patient's knee and ankle joint, as follows:
1. Tibial mechanical shaft.
there. Axial plane of the ankle. As shown in FIG. 63A, an axial plane at the ankle is identified using three or more points on the lower articular surface of the tibia. The three or more points are selected from the same elevation or from closely similar elevations on the lower articular surface of the tibia. This optional step can be used to establish an initial reference plan for subsequent virtual determinations.
lb. Distal point of the tibial mechanical axis. The distal point of the patient's tibial mechanical axis can be defined as the center of the ankle. As shown in FIG. 6-3B, the center of the ankle can be determined virtually by connecting a line from the middle malleolus to the lateral and marking 4 percent medial from the center of the line. For example, if the distance between the malleoli is 100, then the center of the line is 50 and the center of the ankle is 4 percent medial from the center of the line, in other words, 46 of the medial malleoli and 54 of the lateral malleoli. .
33/103 lc. Proximal point of the tibial mechanical axis. The proximal point of the tibial mechanical axis can be determined virtually as the posterior aspect of the ACL insertion point, as shown in FIG. 6-3C.
ld. Tibial mechanical axis. The tibial mechanical axis can be determined virtually as the line connecting the distal and proximal points of the tibial mechanical axis, as shown in FIG. 6-3D.
2. Sagittal plane or A-P of the tibia.
2a. Perpendicular plane of tibial axis (TAPP). TAPP can be determined virtually as the plane perpendicular to the tibial mechanical axis line and including the proximal point of the tibial mechanical axis, as shown in FIG. 6-4A. This optional step can be used to establish a reference plane for subsequent virtual determinations. TAPP, optionally tilted in an A-P orientation, can still be used to determine the tibial cut line.
2b Tibia line A-P - derived from the Cobb method. The tibial line A-P can be determined virtually based on the method derived from Cobb et al. (2008) The anatomical tibial axis, reliable rotational orientation in knee replacement J Bone Joint Surg Br. 90 (8): 1032-8. Specifically, the line A-P of the tibia can be determined virtually as the line perpendicular to the line connecting the diametral centers of the lateral and middle condyles of the tibia. For example, as shown in FIG. 6-4B1 and 6-4B2, a best-fit circle can be drawn to determine the diametrical center of the lateral condyle (ie, the lateral tibial plateau). In addition, a best-fit circle can be sketched to determine the diametrical center of the medial condyle (ie, the medial tibial plateau).
In certain embodiments, one or both circles can be sketched to better match the corresponding condyles on the upper articular surface of the tibia. Alternatively, one or both circles can be sketched to better fit a portion of the wear pattern on the upper articular surface of the tibia. In addition, one or both circles can be sketched to better adjust the condyles at a certain distance from the upper articular surface of the tibia. For example, the circle for the medial condyle
34/103 can be sketched to better adjust the medial condyle at 10 mm, 15 mm, 20 mm, 25 mm or more below, or distal to, the upper articular surface of the tibia; and then the circle can be adjusted proximally to rest on the plane of the upper articular surface of the tibia.
Then, as shown in FIG. 6-4B3, the line A-P of the tibia is determined virtually as the line perpendicular to, and including the midpoint of, the line connecting the diametral centers of the lateral and medial condyles of the tibia. If the midpoint of the line connecting the diametric centers of the lateral and medial condyles is not at the same location as the pro10ximal point of the tibial mechanical axis, then the AP line can be shifted out of the midpoint to include the proximal point of the axis tibial mechanic while remaining perpendicular to the line connecting the diametral centers of the lateral and medial condyles.
Tibia line A-P - derived from the Agaki method. One method
- 15 alternative to virtually determine the A-P line can be derived from other published methods, such as Agaki (2004) An Anteroposterior Axis of the Tibia for Total Knee Arthroplasty, Clin Orthop 420: 213-219.
2c. Sagittal plane or A-P of the tibia. As shown in FIG. 6-4C, the sagittal plantation or A-P of the tibia can be determined virtually as the plane including both the A-P line of the tibia and the line of the tibial mechanical axis. The sagittal plane or A-P is perpendicular to the TAPP.
3. Coronal or medial-lateral (M-L) plane of the tibia. As shown in FIG. 6-4D, the coronal or M-L plane of the tibia can be determined virtually as the plane perpendicular to the A-P plane (or perpendicular to the A-P line) of the tibia and including the tibial mechanical axis line. The coronal plane or M-L is still perpendicular to the TAPP.
2.3.3 Femoral mechanical axis and sagittal and coronal planes
In certain embodiments, the femoral mechanical axis and the femoral sagittal and coronal planes are determined virtually using a model 30 that includes the reference points of a patient's knee and hip joint, as follows:
1. Femoral mechanical axis.
35/103 la. Axial plane of the femur. As shown in FIG. 6-5A, an axial plane of the femur is selected using virtually three or more points within the spherical femoral head that substantially rests on the same axial plane. This optional step can be used to establish an initial reference plan for subsequent virtual determinations.
lb. Proximal point of the femoral mechanical axis. As shown in FIG. 6-5B, the proximal point of the patient's femoral mechanical axis can be determined virtually as the center of the spherical femoral head.
lc. Distal point of the femoral mechanical axis. As shown in FIG. 6-5C, the distal point of the femoral mechanical axis is determined virtually as the point on the posterior aspect of the femoral trochlear notch.
ld. Femoral mechanical axis. The femoral mechanical axis can be determined virtually as the line connecting the distal and proximal points of the femoral mechanical axis, as shown in FIG. 6-5D.
2. Sagittal plane or A-P of the femur.
2a. Perpendicular plane of the femoral mechanical axis (FMAPP). The FMAPP can be determined virtually as a plane perpendicular to the femoral mechanical axis line and including the distal point of the femoral mechanical axis, as shown in FIG. 6-6A. This optional step can be used to establish a reference plane for subsequent virtual determinations. In certain modalities of implant procedures that require femoral cuts, the distal cut is applied to the FMAPP.
2b. A-P line of the femur - derived from the Whiteside line. As shown in FIG. 6-6B, line A-P of the femur can be determined virtually as the line perpendicular to the epicondylar line and passing through the distal point of the femoral mechanical axis. The epicondylar line is the line that connects the medial and lateral epicondyles (more distant points).
2c. Sagittal plane or A-P of the femur. As shown in FIG. 6-6C, the sagittal plane or A-P of the femur can be determined virtually as the plane including both the A-P line of the femur (derived from the
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Whiteside) and the line of the femoral mechanical axis. The sagittal piano or A-P is also perpendicular to the piano perpendicular to the femoral axis.
3. Coronal or medial-lateral (M-L) plane of the femur. As shown in FIG. 6-6D, the coronal piano or M-L of the femur can be determined virtually as the plane perpendicular to the A-P plane (or perpendicular to the A-P line) of the femur and including the femoral mechanical axis line. The coronal plane or M-L is also perpendicular to the plane perpendicular to the femoral axis.
After virtually determining the mechanical tibial and femoral axes, and their sagittal and coronal planes, the lower end can be aligned virtually by adjusting the angle of the intersecting mechanical axes in the knee joint to zero. The axes can be axially aligned by aligning on one or both the sagittal or coronal planes of each axis, as shown in FIGS. 6-6E and 6-6F, respectively. FIGS. 6-7A and 6-7B show a model before and after virtual alignment as it appears in axial view looking distally from a section of the femoral head, to a section of the distal femur, and to a section of the tibia. Similarly, FIGS. 6-7C and 6-7D show a model before and after virtual alignment as they appear on an axial axis looking proximally from a section of the distal tibia, to a section of the distal femur, and in FIG. 67C, for a section of the femoral head. FIGS. 6-7E-7G shows a model before and after virtual alignment (FIGS. 6-7E and G), and overlapping both before and after virtual alignment (FIG. 6-7F).
2.4 Estimated deformity
The loss of cartilage in a compartment can lead to progressive joint deformity. For example, loss of cartilage in a medial compartment of the knee can lead to varus deformity. In certain modalities, the loss of cartilage can be estimated in the affected compartments. The estimation of cartilage loss can be made using an MRI ultrasound or CT scan or other imaging modality, optionally with intravenous or intra-articular contrast. Estimating cartilage loss can be as simple as measuring or estimating
37/103 the amount of loss of joint space seen on X-rays. For the latter, typically standing X-rays are preferred. If cartilage loss is measured from X-rays using loss of joint space, the loss of cartilage on one or two opposing joint surfaces can be estimated by, for example, dividing the measured or estimated loss of joint space by two to reflect the loss of cartilage on an articular surface. Other proportions or calculations are applicable depending on the joint or the location within the joint. Subsequently, a normal cartilage thickness can be virtually established on one or more joint surfaces by the normal cartilage thickness. In this way, a normal or close to normal cartilage surface can be derived. The normal cartilage thickness can be virtually simulated using a computer, for example, based on a computer model, for example, using the adjacent normal cartilage thickness, cartilage in a contralateral joint, or other anatomical information including subchondral bone shape or other joint geometries. Cartilage models and cartilage thickness estimates can also be derived from anatomical reference databases and can be combined, for example, with a patient's weight, sex, height, race, gender or joint geometry (s).
Limb alignment can be virtually corrected by realigning the knee after establishing normal cartilage thickness or shape in the affected compartment by moving the body joints, for example, femur and tibia, so that the opposing cartilage surfaces including any enlarged or derived or virtual cartilage touch each other, typically in the preferred contact areas. These contact areas can be simulated for varying degrees of flexion or extension.
Any current or future method for determining limb alignment and simulating normal knee alignment can be used.
3, Parameters for designing a specific implant for the patient
Patient-specific implants of certain modalities
38/103 can be designed based on specific patient data to optimize one or more parameters including, among others: (1) correction of deformity and limb alignment (2) maximum preservation of bone, cartilage or ligaments, (3) preservation and / or optimization of other characteristics of the patient's biology, such as trochlea and trochlear shape, (4) restoration and / or optimization of joint kinematics, and (5) restoration or optimization of the location of the joint line and / or width of the gap of the joint. articulation. Various aspects of an implant component that can be designed or designed based on specific patient data to help find any number of user-defined limits for these parameters. Aspects of an implant that can be designed and / or designed specifically for the patient may include, but are not limited to, (a) implant shape, external and internal, (b) implant size, (c) and implant thickness.
There are several advantages that a patient-specific implant designed and / or designed to achieve or improve one or more of these parameters can have over a traditional implant. These advantages can include, for example: improved mechanical stability of the end; opportunity for a pre-primary or additional review of the implant; better fit with existing biological or biological characteristics; improved movement and kinematics, and other advantages.
3.1 Deformity correction and limb optimization
Information regarding misalignment and proper mechanical alignment of a patient's limb can be used for preoperative design and / or selecting one or more features of a joint implant and / or implant procedure. For example, based on the difference between the patient's misalignment and the appropriate mechanical axis, a knee implant and implant procedure can be designed and / or selected preoperatively to include implant and / or resection dimensions that substantially realign the patient's limb to correct or improve the patient's alignment deformity. In addition, the process may include selecting and / or drawing one or
39/103 plus surgical tools (for example, guide tools or cutting jigs) to direct the doctor in the resection of the patient's bone according to the dimensions of the resection designed and / or selected preoperatively.
In certain modalities, the degree of deformity correction that is necessary to establish the desired limb alignment is calculated based on the image data. The desired deformity correction can be to achieve any degree of varus or valgus alignment or antecurvatum or recurvatum alignment. In a preferred modality, the desired deformity correction returns the leg to normal alignment, for example, a zero degree of mechanical bioaxis in the coronal plane and absence of genu antecurvatum and recurvatum in the sagittal plane. The correction can be performed in a simple plane, for example, in the coronal plane or in the sagittal plane. The correction can be performed in multiple planes, for example, in the coronal and sagittal planes. In addition, the correction can be performed in three dimensions. For this purpose, three-dimensional representations of the joints can be used.
3.2 Preservation of bone, cartilage or ligament
Traditional orthopedic implants incorporate bone cuts. These bone cuts achieve two objectives: they establish a bone shape that is adapted to the implant and help to obtain a normal or almost normal alignment axis. For example, bone cuts can be used with a knee implant to correct an underlying varus of valgus deformity and to scale the articular surface of the bone to fit a standard surface that faces the bone of a traditional implant component. With a traditional implant, multiple bone cuts are positioned. However, since traditional implants are produced standardized without the use of specific patient information, these bone cuts are pre-adjusted for a certain implant without regard to the patient's unique shape. Thus, when cutting the patient's bone to fit the traditional implant, more bone is discarded than necessary with an implant designed to target the patient's particular structures and disabilities.
3.2.1 Plan bone cuts for one or more articular surfaces
In certain modalities, bone cuts are optimized to preserve the maximum amount of bone for each individual patient, based on a series of two-dimensional images or three-dimensional representations of the patient's joint anatomy and geometry and the desired alignment of the limb and / or correction of desired deformity. Bone cuts on two opposing joint surfaces can be optimized to achieve the minimum amount of bone resection on both joint surfaces.
By adapting the bone cuts in the series of two-dimensional images or three-dimensional representations on two opposing articular surfaces such as, for example, a femoral head and acetabulum, one or both femoral condyles and a tibial plateau, a trochlea and a patella , a glenoid and a humeral head, a talar dome and a tibial ceiling, a distal humerus and a radial head and / or an ulna, or a radius and a scaphoid, certain modalities allow individualized implant designs for the patient, with bone preservation that can assist with appropriate ligament balance and that can help prevent overfilling of the joint, while achieving optimal bone preservation on one or more joint surfaces in each patient.
Bone cuts can also be designed to reach or exceed a certain minimum material thickness, for example, the minimum amount of thickness required to ensure the biomechanical stability and durability of the implant. In certain embodiments, the minimum limiting thickness of the implant can be defined at the intersection of two contiguous cuts of bones on the internal surface that faces the bone of an implant component. For example, in the femoral implant component 700 shown in FIG. 7, the minimum thickness of the implant component appears at one or more intersections 710. In certain embodiments of a femoral implant component, the minimum thickness of the implant can be less than 10 mm, less than 9 mm, less than 8 mm, less than 7
41/103 mm, and / or less than 6 mm.
These optimizations can be performed for one, two or three opposing joint surfaces, for example, on one knee they can be performed on a tibia, a femur and a patella.
3.2.2 Bone cuts optimized for joint surfaces in knee replacement
In one knee, different bone cuts can be planned for a medial and lateral femoral condyle. The medial and lateral femoral condyles have different geometry, including, for example, width, length and 10 rays in multiple planes, for example, the coronal and sagittal planes. Bone cuts can be optimized in the femur individually for each condyle, resulting in bone cuts placed at a different depth or angle in one condyle in relation to the other condyle. For example, a horizontal cut in a medial condyle may be anatomically placed15 more inferiorly in relation to the limb than a horizontal cut in a lateral condyle. The horizontal cut distance of the subchondral can, however, be approximately the same in each condyle. Chamfer cuts in the medial and lateral condyle can be positioned along different ones instead of the same plane to optimize bone preservation. In addition, chamfer cuts in the medial and lateral condyle can be positioned at a different angle to maximize bone preservation. Posterior sections can be placed in a different plane, parallel or non-parallel, in a medial and lateral femoral condyle to maximize bone preservation. A medial condyle may include more bone cuts than a lateral condyle to increase bone preservation or vice versa.
In certain embodiments, a bone preservation measure may include total volume of resected bone, volume of bone resection from one or more resection cuts, volume of bone resection to fit one or more cut bones from the implant component, average thickness bone resection, average bone resection thickness of one or more resection cuts, average bone resection thickness to fit one or more bone cut implant components, thickness
42/103 maximum bone resection, maximum bone resection thickness of one or more resection cuts, maximum bone resection thickness to fit one or more bonebone cut implant components.
Certain modalities are directed at a femoral implant component containing more than five bone cuts, for example, six, seven, eight or more bone cuts on the internal surface that faces the bone of the implant component. Alternatively, certain modalities are aimed at orientations other than five bone cuts, for example, a flexed orientation. A patient-specific implant with a greater number of bone cuts and / or a different orientation of bone cuts can allow for improved bone preservation over a traditional femoral implant with a pattern of five bone cuts and therefore performs a pre-primary implant. However, a patient-specific implant containing bone cuts that are not parallel to the cuts of a subsequent primary can result in the primary implant containing small gaps between the bone and the inner surface that faces the primary implant bone. These small gaps can result in the intersection of misalignment between the pre-primary implant and the subsequent primary implant. For example, as shown in FIG. 7-1, bone cuts (shown in gray) for a pre-primary implant component containing a 5-flex cut can retain bone when compared to a traditional primary implant (shown in outline), but a small gap 730 it can still be created by pre-primary cutting. Any said small gap 730 can be filled with bone cement when fitted to a subsequent primary implant.
In addition to optimizing bone preservation, another factor in determining the depth, number, and / or orientation of resection cuts and / or bone cuts of the implant component is the desired thickness of the implant. Minimum implant thickness can be included as part of the resection cut and / or bone cut design to ensure a threshold force for the implant in the face of stresses and forces associated with joint movement, such as standing, walking and running . Table 2 mos
43/103 traces the results of a finite element analysis (FEA) evaluation for femoral implant components of various sizes and with various numbers of bone sections and orientations. The maximum major stress observed in the FEA analysis can be used to establish a minimum acceptable implant thickness for an implant component containing a particular size and, optionally, for a particular patient (for example, containing a particular weight, age, activity level , etc). Before, during, and / or after establishing a minimum component of the implant thickness, the optimal depth of resection cuts and the optimal number and orientation and resection cuts and bone cuts, for example, for maximum bone preservation, can be designed .
In certain embodiments, a component of the implant design or selection may depend, at least in part, on a minimum threshold component of the implant thickness. In turn, the minimum limiting thickness of the implant component may depend, at least in part, on specific patient data, such as condylar width, length of the femoral transepicondylar axis, and / or specific patient weight. In this way, the limit thickness of the implant, and / or any characteristic component of the implant, can be adapted to a particular patient based on a combination of geometric patient data and patient anthropometric data. This approach can apply to any feature of the implant component for any joint, for example, the knee, hip, or shoulder.
Table 2: Finite Element Analysis for Various Implant Designs
Implant Description Condyle geometry Distai Relative size Scan # Maximum Main Voltage mPa 6-cuts, not inflected coplanar Sigma # 1.5 3017 161 5-cuts, not inflected coplanar Sigma # 1.5 3017 201 6-cuts, flexed 5 degrees coplanar Sigma # 1.5 3017 229 6-cuts, not inflected coplanar Sigma # 3 2825 221 5-cuts, not inflected coplanar Sigma # 3 2825 211 6-cuts, flexed 5 degrees coplanar Sigma # 3 2825 198 5-cuts, not inflected coplanar Sigma # 7 1180 292 6-cuts, not inflected coplanar Sigma # 7 1180 221 6-cuts, flexed 5 degrees coplanar Sigma # 7 1180 214 7-not flexed cuts coplanar Sigma # 7 1180 203 6-cuts, not inflected not coplanar, without step Sigma # 7 1180 173 7-cuts, flexed 5 degrees not coplanar, without step Sigma # 7 1180 202
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A weighting can optionally be applied to each bone with respect to the degree of bone preservation achieved. For example, if maximum bone preservation is desired in a tibia or a subsegment of the tibia, femoral bone cuts can be adapted and moved accordingly to ensure proper implant alignment and ligament balance. Conversely, if maximum bone preservation is desired in a femoral condyle, a tibial bone cut can be adjusted accordingly. If maximum bone preservation is desired in one patella, a bone cut in the opposite trochlea can be adjusted accordingly to ensure maximum patellar bone preservation without inducing any extension deficit. If maximum bone preservation is desired in a trochlea, a bone cut in the opposite patella can be adjusted accordingly to ensure maximum patellar bone preservation without inducing any extension deficit. Any combination is possible at different weights can be applied. Weightings can be applied using mathematical models or, for example, data derived from the patient reference database.
3.2.3 Ligament Preservation
The implant design and modeling can also be used to achieve posterior ligament, for example, with respect to the PCL and / or ACL. An image test can be used, for example, the origin and / or insertion of PCL and ACL in the femur and tibia. The origin and insertion can be identified by viewing, for example, the ligaments directly, as is possible with MRI or spiral CT artography, or by viewing bone landmarks known as the origin or insertion of the ligament such as the anterior and posterior tibial spines.
An implant system can then be selected or designed based on image data so that, for example, the femoral component preserves the ACL and / or PCL origin, and the tibial component preserves the ACL and / or PCL connection. The implant can be selected or designed so that bone cuts adjacent to the ACL or PCL connection or origin do not weaken the bone to induce a potential fracture.
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For ACL preservation, the implant can have two unicompartmental tibial components that can be selected or designed and positioned using image data. Alternatively, the implant may have an anterior bridge component. The width of the anterior bridge in the AP dimension, its thickness in the upper-lower dimension or its length in the mediolateral dimension can be selected or projected using the image data and, specifically, the known insertion of ACL and / or PCL.
Any component of the implant can be selected and / or adapted in shape so that important ligament structures are clear. The image data can assist identification or derive the format or location information in said ligament structures. For example, the lateral femoral condyle of a unicompartmental, bicompartmental or total knee system may include a concavity or divet to avoid the popliteal tendon. In a shoulder, the glenoid component may include a shape or concavity or divet to avoid a subscapular tendon or a tendon in the biceps. In a hip, the femoral component can be selected or designed to avoid an iliopsoas or adductor tendons. 3.3 Establishment of kinematics of normal or almost no joint damage
In certain embodiments, bone cuts and implant shape including at least one of a surface that faces the bone or a surface that faces the implant joint can be designed or selected to obtain normal joint kinematics.
In certain embodiments, a computer program that stimulates the biomotion of one or more joints, such as a knee joint, or a knee and ankle joint, or a hip, knee and / or ankle joint, can be used . In certain modalities, patient-specific image data can be entered into this computer program. For example, a series of two-dimensional images of a knee of a joint patient or a three-dimensional representation of a knee of a patient's joint can be inserted into the
46/103 program. In addition, two-dimensional images or a three-dimensional representation of the patient's ankle and / or hip joint can be added.
Alternatively, patient-specific kinematics data, for example, obtained from a gait lab, can be entered into the computer program. Alternatively, patient-specific navigation data, for example, generated using a surgical navigation system, guided by image or unguided can be entered into the computer program. This kinematics or navigation data can, for example, be generated by applying optical or RF markers to the limb and recording the markers and then measuring the limb movements, for example, flexion, extension, abduction, adduction, rotation, and other limb movements.
Optionally, other data including anthropometric data can be added for each patient. These data may include, but are not limited to, the patient's age, gender, weight, height, size, body mass index, and race. The desired limb alignment and / or deformity correction can be added to this model. The position of bone cuts on one or more articular surfaces as well as the desired location of surfaces that hold the implant on one or more articular surfaces can be inserted into the model.
A patient-specific biomovement model can be derived which includes combinations of parameters listed above. The biomovement model can simulate activities of daily living including normal walking, climbing stairs, descending stairs, running, kneeling, lowering, sitting and any other physical activity. The biomovement model can start with standardized activities, typically derived from the reference database. These reference databases can be, for example, generated using biomovement measurements using force plates and motion trackers using radio frequency or optical markers and video equipment.
The biomovement model can then be individualized with
47/103 the use of patient-specific information including at least one of, among others, the patient's age, gender, weight, height, body mass index, and race, the desired limb alignment or deformity correction, and the data of patient image, for example, a series of two-dimensional images or a three-dimensional representation of the joint for which surgery is contemplated.
An implant format including associated bone cuts generated in previous optimizations, for example, limb alignment, deformity correction, bone preservation on one or more joint surfaces, can be introduced into the model. The parameters measured in the patient-specific biomotion model can include, among others:
On one knee:
Medial femoral retreat during flexion.
Lateral femoral indentation during flexion.
Patellar, medial, lateral, upper, lower position for different flexion and extension angles.
Internal and external rotation of one or more femoral condyles. Internal and external tibial rotation.
Flexion and extension angles of one or more articular surfaces.
Anterior and posterior slides of at least one of the medial and lateral femoral condyles during flexion or extension.
Medial and lateral laxity along the range of motion.
Contact pressure or forces on at least one or more articular surfaces, for example a femoral condyle and a tibial plateau, a trochlea and a patella.
Contact area on at least one or more articular surfaces, for example, a femoral condyle and a tibial plateau, a trochlea and a patella.
Forces between the surface that faces the implant bone, an optional cement interface and the adjacent bone or bone marrow, measured
48/103 at least one or multiple bone cuts or surface that faces the implant bone on at least one or multiple articular surfaces or components of the implant.
Ligament location, for example ACL, PCL, MCL, LCL, retinaculum, joint capsule, estimated or derived, for example using an image test.
Ligament tension, tension, shear force, estimated failure forces, loads for example for different angles of flexion, extension, rotation, abduction, adduction, with the different positions or movements optionally simulated in a virtual environment.
Potential restriction of the implant in other joint structures, for example, in high flexion, high extension, internal or external rotation, abduction or adduction or any combination of them or other angles / positions / movements.
Similar parameters can be measured in other joints, for example in a hip or shoulder:
Internal and external rotation of one or more articular surfaces.
Flexion and extension angles of one or more articular surfaces.
Anterior slide and posterior slide of at least one or more articular surfaces during flexion or extension, abduction or adduction, elevation, internal or external rotation.
Looseness of articulation along the range of motion.
Contact pressure or forces on at least one or more articular surfaces, for example, an acetabulum and a femoral head, a glenoid and a humeral head
Contact pressure or forces on at least one or more articular surfaces, for example, an acetabulum and a femoral head, a glenoid and a humeral head
Forces between the surface that faces the implant bone, an optional cement interface and the adjacent bone or bone marrow, measured
49/103 at least one or multiple bone cuts or surface that faces the implant bone on at least one or multiple articular surfaces or components of the implant.
Ligament location, for example, transverse ligament, glenohumeral ligaments, retinaculum, joint capsule, estimated or derived, for example, using an image test.
Ligament stress, tension, shear force, estimated failure forces, loads, for example, for different flexion, extension, rotation, abduction, adduction angles, with the different positions or movements optionally simulated in a virtual environment.
Potential restriction of the implant in other joint structures, for example, in high flexion, high extension, internal or external rotation, abduction or adduction or elevation or any combination of them or other angles / positions / movements.
What is listed above is not intended to be exhaustive, but only exemplary. Any other biomechanical parameter known in the art can be included in the analysis.
The resulting biomovement data can be used to further optimize the design in order to establish normal or near normal kinematics. Implant optimizations can include one or multiple implant components. Implant optimizations based on patient-specific data including image-based biomotion data include, but are not limited to:
Changes to the shape of the implant facing the external articulation in the coronal plane.
Changes to the shape of the implant facing the external joint in the sagittal plane.
Changes to the shape of the implant facing the external joint in the axial plane.
Changes to the shape of the implant facing the external joint in multiple planes or three dimensions.
Changes to the shape of the implant facing the inter50 / 103 joint in the coronal plane.
Changes to the shape of the implant facing the internal joint in the sagittal plane.
Changes to the shape of the implant facing the internal articulation in the axial plane.
Changes to the shape of the implant facing the internal joint in multiple planes or three dimensions.
Changes in one or more bone cuts, for example in relation to the depth of the cut, orientation of the cut.
Any single or combinations of the above or all on at least one joint surface or component of the implant or multiple joint surfaces or components of the implant.
When changes are made to multiple joint surfaces or components of the implant, they can be made in reference to or attached to each other. For example, in the knee, a change made to a femoral bone cut based on patient-specific biomovement data can be referenced to or linked with a change concomitant with a bone cut on an opposite tibial surface, for example, if less femoral bone is resected, the computer program can choose to resect more tibial bone.
Similarly, if a femoral implant shape is altered, for example on an external surface, it can be achieved by a change in the shape of the tibial component. This is, for example, particularly applicable when fewer parts of the surface that comprises the tibia fit negatively to the femoral surface that faces the joint.
Similarly, if the footprint of a femoral implant is enlarged, this can be achieved by enlarging the surface that includes a tibial component. Similarly, if a tibial implant shape is changed, for example, on an external surface, it can be achieved by a change in the shape of the femoral component. This is, for example, particularly applicable when fewer parts of the femoral support surface fit negatively to the tibial surface facing
51/103 articulation.
Similarly, if a radius of the patellar component is enlarged, this can be achieved by enlarging the radius of the opposite trochlear support surface, or vice versa.
These linked changes can also be applied to hip and / or shoulder implants. For example, if a femoral implant shape is changed, for example on an external surface, it can be achieved by a change in the shape of the acetabular component. This is, for example, particularly applicable when fewer parts of the acetabular support surface fit negatively to the femoral surface that faces the joint. In a shoulder, if a glenoid implant shape is changed, for example on an external surface, this can be achieved by a change in the shape of the humeral component. This is, for example, particularly applicable when fewer parts of the humeral support surface are they fit negatively to the glenoid surface that faces the joint.
Any combination is possible and this refers to the shape, orientation and size of the implant components on two or more opposite surfaces.
By optimizing the shape of the implant in this way, it is possible to establish normal or near normal kinematics. In addition, it is possible to avoid complications related to the implant, including, among others, anterior notching, notch impact, impact of posterior femoral component in high flexion, and other complications associated with existing implant designs. For example, certain designs of the femoral components of traditional knee implants attempted to address the limitations associated with traditional knee implants in high flexion by changing the thickness of the distal and / or posterior condyles of the femoral implant component or by changing the height of the posterior condyles of the component of the femoral implant. Since these traditional implants accompany the approach, one size fits all, they are limited by altering only one or two aspects of an implant design. However, with
52/103 the design approaches described here, various characteristics of an implant component can be designed for an individual to address various issues, including issues associated with high flexion movement. For example, the designs as described here can alter a component of the implant surface that faces the bone (for example, number, angle and orientation of bone cuts), surface that faces the joint (for example, surface contour and curvature) and other characteristics (for example, implant height, width, and other characteristics) to address issues with high flexion along with other issues.
The biomovement model can be complemented with the patient's finite element modality or other biomechanical models known in the art.
The resulting forces on the knee joint can be calculated for each component for each specific patient. The implant can be designed for the patient's load and strength demands. For example, a 125-pound patient may not need a tibial plateau as thick as a 280-pound patient. Similarly, polyethylene can be adjusted in shape, thickness and material properties for each patient. A 3mm polyethylene insert can be used on a light patient with weak strength and a heavier or more active patient may need an 8mm polymer insert or similar device.
3.4 Restoration or optimization of the joint line width of the joint gap
Traditional implants often change the location of a patient's existing or natural joint line. For example, with a traditional implant, the patient's joint line can be compensated proximally or distally when compared to the joint line corresponding to the corresponding limb. This can cause mechanical asymmetry between the limbs and results in uneven movement or mechanical instability when the limbs are used together. A compensating joint line with a traditional implant can also make the patient's body appear asymmetrical.
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Traditional implants often change the location of a patient's existing or natural joint line because they have a standard thickness that is thinner or thicker than the bone and / or cartilage they are replacing. For example, a schematic of a traditional implant component is shown in FIGS. 7-2A and 7-2B. In the figure, the dashed line represents the existing or natural articulation line of the patient 740 and the dotted line represents the compensating articulation line 742 after the insertion of the traditional implant component 750. As shown in FIG. 7-2A, the traditional implant component 750 with a standard thickness replaces a drying of part 752 of a first biological structure 754 at an articulation between a first biological structure 754 and a second biological structure 756. The resected part 752 of the biological structure may include , for example, bone and / or cartilage, and the biological structure 754 can include bone and / or cartilage. In the figure, the standard thickness of the traditional implant component 750 differs from the thickness of the resected part 752. Therefore, as shown in FIG. 72B, replacing the resected part 752 with the traditional implant component 750 creates a wider gap in the joint 758 and / or a compensating joint line. Surgeons can target the enlarged joint gap 758 but by pulling biological structure 756 toward the first biological structure 754 and adjusting the ligaments associated with the joint. However, while this change restores some of the mechanical instabilities created by an enlarged joint gap, it also exacerbates the displacement of the joint line.
Certain modalities are addressed to the implant components θ related drawings and methods, containing one or more aspects that are designed from specific patient data to re-establish or optimize the location of the patient's particular joint line. In addition or alternatively, certain patient-specific implant components, and related designs and methods, may have one or more aspects that are designed from patient-specific data to restore or optimize the patient's particular joint width.
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3.4.1 Location of the articulation line
In certain embodiments, an implant component can be designed on specific patient data to include a thickness profile between its joint-facing surface and its bone-facing surface to restore and / or optimize the location of the particular joint line of the patient. For example, as schematically described in FIG. 7-3, the thickness profile (shown as A) of the patient-specific implant component 760 can be designed to, at least in part, substantially fit positively at a distance from an existing or natural joint line from patient 740 to the an articular surface of the biological structure 754 and the implant 760 engages. In the diagram described in the figure, the width of the gap in the patient's joint is also retained.
The matching thickness profile can be designed based on one or more of the following considerations: the thickness (shown as A 'in FIG 7-3) of a resected piece of the biological structure that the implant replaces; the thickness of the missing or fallen biological structure that the implant replaces; the relative compressibility of the implant material and the biological material that the implant replaces; and the thickness of the saw blade used for resection and / or loss of material in removing the resection from the part.
For modalities targeting an implant thickness component that is designed based on specific patient data to optimize the location of the joint line (and / or other parameters such as preserving bone), the minimum acceptable implant thickness can be a significant consideration. The minimum acceptable thickness can be determined based on any criteria, such as minimum mechanical strength, for example, as determined by FEA. Thus, in certain embodiments, an implant or implant design includes an implant component containing a minimum thickness profile. For example, in certain embodiments, a pre-primary component or primary femoral implant may include a thickness between the surface that faces the joint and the surface that
55/103 faces the bone of the implant component which is less than 5 mm, less than 4 mm, less than 3 mm, and / or less than 2 mm.
In certain embodiments, the thickness of the implant component can vary from about 2 mm to about 3 mm. Therefore, for patients requiring only minimal bone resection of no more than 2 to 3 mm deep from the joint line, an implant component designed with a thickness to substantially fit positively to bone resection of 2 to 3 mm can maintain the location of the joint line. In addition, a subsequent traditional primary implant, for example, 5 mm or more in thickness can be applied with an additional cut depth of 3 to 2 mm or greater (for a total cutting depth of 5 mm). This can allow the joint line to be maintained with the subsequent primer as such.
Certain modalities aimed at implants or implant designs optimized to achieve minimum implant thickness may include a greater number of bone cuts, for example, six, seven, eight or more bone cuts, on the inner surface that faces the implant bone. Bone cuts can be oriented in various dimensions, for example, in the flexed orientation. In addition, certain embodiments may include on the internal surface facing the bone any combination of linear cuts, curvilinear cuts, and / or portions that substantially fit positively to an uncut articular bone surface. For example, as described in Example 13, an implant or implant design can include a linear anterior cut, a linear posterior cut, and a curvilinear cut between them. As described in FIG. 7-4, an implant or implant design 770 may include a distal linear cut 772, a linear anterior cut 774, a linear posterior cut 776, and curved chamfer cuts 778 between them to substantially negatively fit the corresponding drawn cuts to the femur 780. As described in Example 14, an implant or implant design may on the inner surface that faces the bone one or no linear cut and portions that substantially fit positively to a non-cut joint bone surface56 / 103 of the.
The internal surface that faces the bone of the implant component can be designed to substantially fit negatively to the surface of the cut bone, both curved in linear portions. The curved cuts to the bone can be made with a routing saw, as described in Example 13. Any number of cuts can be 2 to 3 mm deep, and the thickness of the implant component can be designed to positively fit the depth of the cut through part of the implant or through the total implant.
By positively fitting the thickness profile of the implant component with the depth profile of the cut, and negatively fitting the surface of the component that faces the bone with the articular surface of the cut of the biological structure, certain aspects of the component of the surface that faces the joint they can positively fit the corresponding aspects of the surface of the biological structure it replaces. For example, if the internal surface of the component and the thickness match the corresponding characteristics of the biological structure, the curvature of the component that faces the joint, such as a j curve, can also match the corresponding curvature of the patient's biological structure.
3.4.2 Joint gap width
In certain embodiments, one or more implant components can be designed based on specific patient data to include a thickness profile that retains, restores, and / or optimizes the particular joint in the patient's gap width. For example, as schematically described in FIG. 7-5A and 7-5B, patient-specific implant components 785, 786 can be designed to, at least in part, substantially positively fit into the existing or natural joint gap of patient 788. In the figure, the dashed line represents the existing or natural articulation line of the patient 790. The patient-specific implant components 785, 786 do not have thicknesses that fit the corresponding resected parts 792, 794 of the biological structures 796, 798. However, as shown in FIG. 7-5B, the
57/103 implant components 785, 786 are designed to retain the specific width of the patient's gap 788.
If the thickness of an implant component is greater than the corresponding bone cut depth, then the thicker implant component can alter the line below the joint. However, as shown in FIG. 7-5A and 7-5B, the width of the joint gap can be retained by drawing a second implant component to compensate for the greater thickness of the first implant component. For example, in total knee replacement that includes both the femoral implant component and a tibial implant component, if the femoral implant component is thicker than the corresponding bone cut depth, more tibial bone can be cut and / or a thinner tibial implant can be used. In certain embodiments, a cut of tibial bone and / or the thickness of a corresponding part of a tibial implant component may be less than about 6 mm, less than about 5 mm, less than about 4 mm, less than about 3 mm, and / or less than about 2 mm.
One or more components of a tibial implant can be designed to be thinner to retain, restore, and / or optimize the patient joint line and / or joint gap width. For example, one or both of the tibial tray inserts and the tibial tray (for example, a poly insert) can be designed and / or selected (for example, selected preoperatively) as being more end in one or more locations for direct the joint line and / or joint gap issues to a particular patient. In certain embodiments, a cut of tibial bone and / or the thickness of a corresponding part of a tibial implant component may be less than about 6 mm, less than about 5 mm, less than about 4 mm, less than about 3 mm, and / or less than about 2 mm.
In certain embodiments, one or more implant components can be designed based on specific patient data to include a thickness profile that retains, or changes, a gap width
58/103 particular condition of the patient or retain or correct another specific characteristic of the patient. For example, patient-specific data can include data regarding the length of the patient's limb (for example, left and right limbs) and the implant components can be designed to, at least in part, change the length of a limb to better match the length of the corresponding member.
Parameter analysis and computer aided design
Any combination of the above modalities is possible. For example, a series of operations can be performed, optionally with a computer driven by software, to transform patient data into an output to identify for a user the best compromise between one or more of the following parameters: (a) alignment and correction of limb deformity, (b) bone preservation through the adjustment of orientation and location of bone cuts, (c) establishment of normal or near normal articulation kinematics including ligament function and implant impact, (d) implant shape, external and internal, (e) implant size, (f) implant thickness, (g) location of the joint line, and (h) location and preservation of the trochlea and trochlear shape. Joint kinematics optimization may include, as another parameter, the objective of not moving the joint line after the operation or minimizing any movement of the joint line, or any limit value or cut-off values for movement of the joint line higher or lower . Kinematics optimization of the joint may also include ligament load or function during movement. Optimization of implant thickness can include femur and / or condyle size and patient weight. For example, in certain embodiments, a patient-specific implant component design may depend, at least in part, on optimizing the thickness of the implant. However, the optimized implant thickness may depend, at least in part, on the specific condylar width of the patient or the length of the transepicondylar axis of the femur and the specific weight of the patient. Thus, the thickness of the implant or any of the implant parameters mentioned above, can be optimized (ie adapted to a pa
59/103 particular patient) based on specific patient geometric data and patient anthropometric data. This approach can be applied to any parameter of the implant of any joint, for example, the knee, the hip, or the shoulder.
4.1 Process flow
Any of the parameters identified above can be the first set of parameters or determined in an optimization. Alternatively, the process can be iterative in nature. This can be completely automated or it can be partially automated allowing user interaction. User interaction can be particularly useful for quality assurance purposes. Different weightings can be applied to any of these parameters, for example, based on the patient's age, surgeon's preference or patient's preference. Feedback mechanisms can be used to show the user or the software which changes in certain parameter values based on desired changes to one or more parameters. For example, a feedback mechanism can indicate the changes that occur for limb alignment and correction of deformity or joint kinematics parameters if a desired change is applied to minimize bone cuts for bone preservation. Thus, the shape of the implant can be modeled and modified to achieve the ideal solution.
In certain modalities, mathematical modeling can be applied to find an ideal solution, for example, according to the parameter limits selected by the user and / or relative weights selected by the user for the parameters included in the model. Alternatively, a solution can be defined using clinical data, for example obtained from clinical studies or intraoperative data.
4.2 Computer-aided design
The processing of patient data, the design of one or more components of a specific implant for the patient, the production of the designed implant, and / or the implantation procedure can be partially or fully automated. For example, patient data,
60/103 with optional user-defined parameters, can be assigned or transferred by a user and / or by electronic transfer in a computer system directed by software that performs a series of operations to generate one or more virtual models or design specifications. implant. The design data of the implant, with optional parameters defined by the user, can be imputed or transferred by a user and / or by electronic transfer in a computer system directed by software that performs a series of operations to transform the data and optional parameters into one or more specifications for manufacturing the implant. The implant design data or implant production data, optionally with user-defined parameters, can be imputed or transferred by a user and / or by electronic transfer in a software-driven computer system that targets one or more manufacturing instruments to produce one or more implant components from a starting material, such as a raw material or blank starting material. The implant design data, implant production data, or implant data, optionally with optional user-defined parameters, can be imputed or transferred by a user and / or by electronic transfer in a computer system directed by software that performs a series of operations to transform the data and optional parameters into one or more specifications for the surgical procedure. The implant design data, implant production data, implant data, or surgical procedure data, optionally with user-defined parameters, can be imputed or transferred by a user and / or by electronic transfer in a targeted computer system by software that directs one or more automated surgical instruments, for example, a robot, to perform one or more surgical steps. In certain embodiments, one or more of these actions can be performed as in a simple process by one or more computer systems driven by software.
A computer operation according to a software program can be used to evaluate a combination of selected parameters
61/103 user-defined and / or weighted and then reports to a user the output values or ranges for those parameters. For example, in certain modalities, the following parameters can be optimized for each patient's implant: tibial cut height (preferably minimized); articulation line position (preferably preserve the natural kinematics); and thickness of the femoral cut (preferably minimized).
The optimization of multiple parameters can result in conflict restrictions; for example, optimizing a parameter causes an unwanted deviation in one or all parameters. In cases where not all restrictions can be achieved at the same time, the parameters can be assigned a priority or weight in the software program depending on the user's desired design goals, for example, minimizing bone loss, or joint line retention to preserve the kinematics, or combination to accommodate both parameters in the overall design.
In an automated process or process step performed by the computer system, restrictions pertaining to a specific implant model, a group of patients or the individual patient can be taken into account. For example, the maximum implant thickness or permitted implant anchor positions may depend on the type of implant. The minimum thickness of the implant may depend on the patient's bone quality.
In certain embodiments, the final implant includes one or more bone cuts. The cutting plan for these bone cuts can be automatically determined by the computer system, for example using anatomical landmarks. In certain embodiments, a computer program can assist in determining bone cuts that are optimized to preserve the maximum amount of bone for each individual patient based on a series of two-dimensional images or a three-dimensional representation of joint anatomy and geometry and the desired alignment of the limb and / or the desired correction of deformity. Optionally, the cutting plane can be adjusted by the operator.
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The computer system can also build the surfaces of the implant. The surfaces can be composed of different elements. In certain embodiments, the surface elements conform to the patient's anatomy. In these situations, the computer system can build a surface using the patient's anatomical model, for example, by building a surface that is identical with or mainly parallel to the patient's anatomical surface. In certain embodiments, the computer system uses geometric elements such as arcs or planes to build a surface. Transitions between surfaces can be smoothed using cones or fillets. In addition, the computer system can take into account restrictions such as minimum or maximum thickness or length or curvature of parts or aspects of the implant when building the surfaces.
In another embodiment, the computer system can automatically or semi-automatically add features to the implant design. For example, the computer system may add dowels or anchors or other connection mechanisms. The system can place the features using anatomical landmarks. Restrictions can be used to restrict the placement of features. Examples of restrictions for placement of dowels are the distance between dowels and dowels to the edge of the implant, the height of the dowels that results from their positions in the implant, and forcing the dowels to be located in the center line. Optionally, the system can allow the user to fine-tune the pin placement, with or without compliance with restrictions.
4.3 Libraries
As described here, implants of various sizes, shapes, curvatures and thicknesses with various types and locations and orientations and number of bone cuts can be designed and produced. The implant designs and / or implant components can be cataloged and stored to create a library. The library can be a virtual library of implants, or components, or elements that can be combined and / or altered to create a final implant. The library can include
63/103 a catalog of physical components of the implant. In certain embodiments, the physical components of the implant can be identified and selected using the library. The library can include previously generated components of the implant containing one or more aspects specific to the patient, and / or components with standard or white aspects that can be changed to be specific for the patient. Thus, implants and / or aspects of the implant can be selected from a library. FIGS. 7-6A - 7-6K show components of the implant with exemplary aspects that can be included in said library.
A virtual or physical implant component can be selected from a library based on similarity to previous parameter optimizations or baseline, such as one or more of (1) deformity correction and limb alignment (2) maximum preservation of bone, cartilage or ligaments, (3) preservation and / or optimization of other characteristics of the patient's biology, such as trochlea and trochlear shape, (4) restoration and / or optimization of joint kinematics, and (5) restoration or optimization of the location of the joint and / or width of the joint gap. Thus, one or more aspects of the implant, such as (a) implant shape, external and internal, (b) implant size, and / or (c) implant thickness, can be precisely determined and / or determined within a range library selection. Then, the selected component of the implant can be designed or designed to include one or more specific aspects of the patient. For example, a joint can be evaluated on a particular subject and a pre-existing design of the implant containing the closest shape and size and performance characteristics can be selected from the library for further manipulation (for example, modeling) and production before deployment. For a library including physical components of the implant, the selected physical component can be changed to include a patient-specific aspect when adding material (for example, laser sintering) and / or subtracting material (for example, machining).
Thus, an implant component can include one or more of the
64/103 points designed specifically for the patient and one or more aspects generated from one or more library sources. For example, when designing an implant for a total knee replacement comprising a femoral component and a tibial component, one component can include one or more aspects specific to the patient and the other component can be selected from a library. Table 3 includes an exemplary list of possible combinations.
TABEI-A 3: Illustrative Combinations of Patient-Specific Components and Library Derivatives __________________________________.
Implant components Implant components containing a specific aspect of the patient Implant components containing a library-derived appearance Femoral, tibial Femoral and tibial Femoral and tibial Femoral, tibial Femoral Femoral and tibial Femoral, tibial Tibial Femoral and tibial Femoral, tibial Femoral and tibial Femoral Femoral, tibial Femoral and tibial Tibial Femoral, tibial Femoral and tibial none
Design or select aspects of knee implant components
The following subsections describe aspects of certain model modalities, implant designs, implants, and implant components related to knee replacement. While the sections particularly describe knee implant modalities, it should be understood that the teachings are applicable to other modalities including, but not limited to, shoulder implants and hip implants.
5.1 Femoral implant component
A traditional total knee implant used in knee arthroplasty (TKA) typically includes: an outer surface that faces the joint (ie, lower surface) containing a standard topography; an internal surface that faces the bone (i.e., upper surface) that includes five standard bone cuts; and a standard implant thickness between the surface that faces the joint and the surface that faces the bone. FIG. 8 shows the standard bone cuts that are resected from a subject's bone to fit a traditional total knee implant. Speci
65/103, FIG. 8 shows a coronal view of a patient's femoral bone 800. Bone cuts typically performed with a traditional total knee implant include a horizontal cut 810, an anterior cut 820, a posterior cut 830 next to each femoral condyle, a cut in anterior chamfer 840, and a posterior chamfer cut 850. The anterior and posterior cuts 820, 830 are typically placed in a substantially coronal plane. With a traditional implant, these five standard bone cuts are made to approximately negatively fit the standard five-faceted shape to the inner surface that faces the bone of a traditional implant. In other words, the patient's bone is cut to fit the shape of the traditional implant.
In contrast, in various modalities described here, one or more characteristics of an implant component and / or implant procedure are designed and / or selected to provide an implant component adapted to the patient. For example, in certain embodiments, one or more features of an implant component and / or implant procedure are designed and / or selected preoperatively, based on specific patient data, to substantially fit (for example, substantially negatively fit) and / or substantially fit positively) one or more of the patient's biological structures or a predetermined percentage of it. For example, in certain embodiments, a femoral implant component may include an external surface that faces the joint (i.e., lower surface) containing a sagittal curve or j in one or both condyles that, at least in part, positively fit to the corresponding bone or cartilage curvature in the patient's uncut femur. This specific feature of the implant component for the patient can be selected and / or drawn preoperatively based on the dimensions of the patient's joint as seen, for example, in a series of two-dimensional images or a generated three-dimensional representation, for example, from a CT scan or MRI scan.
5.1.1 Size
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In certain embodiments, the minimum thickness, the maximum thickness, the thickness through the complete component, and / or one or more other aspects of a femoral implant component, can be designed to match or resemble the patient's dimensions, optimized dimensions , and / or standard dimensions. Standard dimensions can be used, for example, to engage one or more standard dimensions with an opposing component.
In certain embodiments, the minimum implant thickness is less than 9 mm, less than 8 mm, less than 7 mm, less than 6 mm, and / or less than 5 mm. In certain embodiments, this minimum implant thickness may allow for a subsequent knee implant using a primary implant.
5.1.2 Surface that faces the joint
In certain respects, the surface facing the joint of a femoral implant component includes one or more specific dimensions of the patient, for example, which positively or negatively fit the biological structure of the patient or which are designed to provide an optimal fit based on the parameters derived from patient-specific data.
The surface facing the joint of an implant component may include a support surface that contacts one or more other surfaces in the joint during the proper function of the joint. In a total knee implant, the support surfaces may include the medial and lateral condyles on a surface that faces the joint of the femoral component and the corresponding surface on the tibial component that contacts the medial and lateral condyles of the femoral component during the proper functioning of the articulation. Supporting surfaces can also include the trochlear area of a femoral implant component and the corresponding patella surface or patella implant component. In certain embodiments, the femoral implant component can be designed and / or selected to include a surface that faces the joint that substantially fits negatively into one or more dimensions of a super
67/103 opposite surface, such as a tibial or patellar surface, of the patient's biological structure or other component of the implant, such as a tibial implant component or a patellar component of the implant.
One or more of the support surfaces in a femoral component may be of a standard design, for example, available in 6 or 7 different formats, with a single radius or multiple radii in one dimension or more than one dimension. Alternatively, a support surface can be standardized in one or more dimensions and adapted to the patient in one or more dimensions. Constant and variable radii can be selected in one dimension or multiple dimensions. Some of the rays can, for example, be adapted to the patient. For example, in a knee implant, different radii can be selected in a medial and a lateral condyle. In addition, portions of a condyle can be patient-specific, while portions of the condyle or another entire condyle can be standardized in shape.
5.1.3 Femoral condyles - sagittal and coronal curvatures
The middle and lateral surfaces of the femoral condyle are the main loading surfaces of a femoral implant component that engage the tibia or a tibial implant component in a knee joint. Thus, the design of these surfaces, and the design for how they engage the opposite surface in a corresponding tibial component, can affect several design parameters described above, including implant wear and kinematics, particularly the proper movement of the implant in the joint. FIGS. 8-1A and 8-1B shows the loading surfaces of a femoral implant component in a coronal view (FIG. 8-1 A) and in a sagittal view (FIG. 8-1B). As indicated by the figures, the load bearing surface in each condyle has a coronal curvature 1210 and a sagittal curvature 1220. In certain embodiments, any one or more of the coronal curvature of the medial condyle, the sagittal curvature of the medial condyle, the coronal curvature of the lateral condyle, and / or the sagittal curvature of the lateral condyle may include, at least in part, patient-specific rays. The remaining curvatures with non-specific patient radii may include radii
68/103 that are designed or optimized with respect to any of the parameters described above and / or radii that are standard, for example, as selected from a family of curvatures. For example, a median condyle can be partially adapted to the patient with respect to sagittal curvature and has a standard curvature in the coronal plane, while a lateral condyle can have a standard curvature in both the coronal and sagittal planes.
In preferred embodiments, the femoral implant component is designed to include one or both condylar support surfaces containing the sagittal curvature with, at least in part, patient-specific radii and a coronal curvature with a standard curvature. For example, the coronal curvature can be selected by choosing from a family of standard curvatures to a standard curvature that is more similar to the external rays of the patient's uncut femoral condyle. Alternatively, the curvature can be selected by choosing from a family of standard curvatures a standard curvature with larger radii to achieve a situation of less biomechanical restriction, or with smaller radii to achieve a more restricted biomechanical situation during knee movement.
The coronal radius of a typical human femoral condyle can vary from 20 to 30 mm. In certain embodiments, the coronal radius of one or both condyles in a femoral implant component may be greater than 20 mm, greater than 30 mm, between 20 and 40 mm, or between 30 and 40 mm. FIGS. 82A and 8-2B show cross sections of a coronal view of two sections of the femoral condyle of a femoral component. As shown, the cross-sectional component has a maximum thickness, but the component in FIG. 8-2A has a larger coronal radius than the component in FIG. 8-2B. As can be seen from the figures, where the maximum thickness is the same for the two components, the component with a larger coronal radius allows more material at the component's edge, and therefore it may be less likely to fail in this area of the component of the femoral implant.
In certain embodiments, the sagittal or j curve of the femoral component can be designed to be inclined to allow for thicker material in the corresponding tibial implant, as shown in FIG. 8-2C.
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Since the AP inclination of the tibial cut in certain modalities is anatomical, the patient's J curve can be tilted by the same anatomical inclination to achieve a previously thicker poly. For example, the patient's J curve can be tilted by the same anatomical inclination in both the medial and lateral condyles of a component of the femoral implant. Alternatively, the patient's J curve can be tilted to anatomical tilt only in the medial condyle and the lateral condyle curve can remain at a certain angle. Alternatively, the patient's J curve can be tilted to the anatomical tilt only at the lateral condyle and the median condyle curve can remain at a certain angle. In certain embodiments, some materials can be removed from the posterior aspect of one or both condyles to allow rotation.
FIGS. 8-3A - 8-3F include additional information regarding the design of the coronal and / or sagittal curves or j curves for certain modalities of the patient-specific femoral implant components. In certain modalities, the middle condyle can be designed to be 5mm lateral, which can help to lateralize the patella. In a certain embodiment, the intercondylar width can be patient-specific. Alternatively or in addition, a minimum intercondylar width, such as 40 mm, can be used if the specific patient width is less than the minimum.
5.1.4 Planning of cutting and placing
In traditional knee implant systems, the anterior or trochlear bone cut is located substantially in the coronal plane and is parallel to the two posterior condylar cuts, as shown in FIG. 9A. FIGS. 9-1A - 9-1C show femoral implant component with three exemplary bone cuts. In certain modalities, bone cuts are rotated or oriented based on a certain flexion of the knee angle. An example of a flexed fit design is described in Example 2, below. Any number of cutting plan can be included in an implant device designed with flexed fit cuts. For example, two, three, four, five, six, seven, eight, nine or more cutting planes can be included in a flexed fit design. One or more of the cuts
70/103 can be curved or the complete surface that faces the bone can be curved. The cuts can be oriented in any rotation, for example, in 5, greater than 5, 10, greater than 10, 15, greater than 15, 20, greater than 20, 25, or greater than 25 degrees of flexion of the axis perpendicular to the sagittal femoris.
5.1.4.1 ______ Anterior condylar veneers
In certain embodiments, the anterior or trochlear facet of the implant is substantially non-parallel to the coronal plane, as exemplified by the dotted 1-cut line in FIG. 9B. For example, the anterior or trochlear cut can be parallel to a tangent through two peaks of areas of the trochlea, as shown in FIG. 9B. By placing the facet of the implant at an angle to the patient's coronal plane, for example, parallel to a tangent of the medial and lateral trochlear peak areas, a substantial amount of bone can be preserved. In certain embodiments, two cuts of trochlear bones can be positioned for an implant with two trochlear facets, as exemplified by the full line of 2 cuts in FIG. 9B. For example, one of the two cuts can be substantially parallel to the medial trochlear facet and the other can be substantially parallel to the lateral trochlear facet. This may be improving the degree of bone preservation.
5.1.4.2 ______ Posterior condylar veneers
In traditional knee implant systems, the posterior medial and lateral condyles are cut in the same plane as each other, substantially parallel to each other, and substantially parallel to the anterior cut. However, in certain embodiments, the implant may have posterior condylar facets that are not parallel and / or not on the same plane as each other. Alternatively, or in addition, the implant may have posterior condylar facets that are substantially not parallel to each other. Alternatively, or in addition, the implant may have posterior condylar facets that are substantially not parallel to the anterior cut.
In certain preferred embodiments, the posterior condylar cut to the middle side can be perpendicular to the long axis of the middle condyle.
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The posterior condylar cut to the lateral side can be perpendicular to the long axis of the lateral condyle.
In certain embodiments, the anterior and posterior sections can be substantially non-parallel to the coronal plane in the upper-lower orientation, as shown in FIG. 10.
5.1.4.3 ______Distal facets
In certain embodiments, the medial and lateral sides of a distal facet of a femoral implant component can be cut in the same plane as the other and / or substantially parallel to each other. However, in certain embodiments, the implant may have a distal facet with posterior portions that are not parallel and / or not in the same plane as each other. Alternatively, or in addition, the implant may have a distal facet that includes portions at separate heights.
5.1.4.4 ______ Chamfered veneers
Traditional implant systems include an anterior and a posterior chamfered facet. However, in certain embodiments, additional chamfered facets may be included. Additional chamfer cuts can be substantially tangent to an articular surface. For example, one or more additional anterior chamfer cuts can be included and / or one or more additional posterior chamfer cuts can be included. By increasing the number of chamfered facets in the implant and positioning the cuts close to the tangent of the joint surface, additional bone can be preserved. In certain embodiments, the cutting plane for one or more of the previous chamfer cuts can be defined by the extent of the trochlear gap in the patient's joint. Specifically, one or more of the previous cutting planes can be designed so that there is no exposed surface on the side that faces the implant component bone in the trochlear gap.
Cutting strategies
Computer software can be used that calculates the closest possible location of the cuts in relation to an articular surface, so that all the intersections of contiguous cuts are only in the
72/103 alone, rather than outside the joint surface. The software can move the cuts progressively closer to an articular surface. When all the intersections reach the level of the endosteal bone or the level of the subchondral bone, the maximum external location of the cuts is achieved and, with this, the maximum amount of bone preservation.
In certain embodiments, bone cuts for an implant can be optimized based on a projected condyle curvature. Specifically, a model or mathematical formula can be used to design an optimized or corrected condyle shape. For example, the lateral condyle is generally found to be deformed or hypoplastic for the patient in need of knee replacement, so an optimized lateral condyle may include additional radius and / or material added to the external condylar surface that faces the implant joint in the condyle when compared to the patient's uncut native condyle. Hypoplastic lateral condyles may be present in 20% of patients who require knee replacement.
The mathematical model or formula used to project the condyle curvature can be based on one or more specific dimensions of the patient. In certain embodiments, the lateral condyle can be designed to have a curvature in relation to the curvature of the patient's medial condyle. For example, the side J curve can be designed to have a smaller radius, for example, a radius 5%, 10%, 15%, 20%, 10-15%, and / or 0-20% less than the curve Medial J of the patient.
The increase in radius and / or material outside the condyle can be used to draw a material saving inside the corresponding section of the implant component, thus keeping the implant material / thickness to a minimum. In this way, by adding radius and / or material to the external contour of the condyle implant, a minimum material thickness of the implant can be achieved externally. This allows for less material on the inner surface that faces the implant bone and thus less bone to be cut from the patient's corresponding condyle. This approach can also be used to correct condyle shape abnormalities, such as
73/103 abnormalities of the lateral condyle, such as hypoplasia, using specific implants for the patient.
5.1.5 Cement Bolts and Pockets
The femoral components of the implant of certain modalities can also include other characteristics that are specific to the patient and / or optimized according to one or more of the parameters discussed above.
The design of the component connecting bolts also includes features that are specific to the patient and / or optimized according to one or more of the parameters discussed above. For example, the fixation pins can be flexed in relation to the biomechanical or anatomical axes.
The design of the bone cement pocket or pockets component still includes features that are specific to the patient and / or optimized according to one or more of the parameters discussed above. FIGS. 11A and 11B show pockets of bone cement in a component of some modalities (FIG. 11A) and in a traditional component (FIG. 11B). As shown in FIG. 11 A, each section or facet of the surface that faces the component's bone may have an independent cement pocket. One or more of the cement pockets can be offset from the periphery by 2 mm or more. Each pocket can have a maximum depth of less than 0.9 mm, for example, 0.5 mm or less.
5.1.6 Patella veneers of the femoral implant component
In traditional total knee replacement systems, a single patellar facet is used that is typically substantially parallel to the coronal plane. Patellar revision can be very challenging and bone preservation is preferred in the patella. In certain embodiments, two or more patellar facets can be used in the implant. Patellar veneers can be patient-specific, that is, designed to match the normal patellar tracking in the trochlear sulcus. Alternatively, the patellar facets can be optimized, that is, improve the kinematics between surfaces of the components. A method for designing a specific implant for the
74/103 patient to optimize the patellar groove together with the trochlear groove of a femoral implant component is described below in Example 4. Specifically, the exemplary implant design in Example 4 uses a patient-specific sagittal curvature and a projected coronal curvature to allow the patella component to adequately follow the trochlear groove.
In certain other embodiments, the coronal curvature may additionally be patient-specific. In certain embodiments, the coronal curvature is patient-specific and the sagittal curvature is standard or projected.
The patellar veneers are positioned through two or more 10 patellar bone cuts. The two or more patellar facets can be substantially tangent or parallel to the medial and lateral facet. Optionally, they can also be substantially tangent or parallel to the upper and lower patellar facets, in particular, when more than two facets of the implant or bone cuts are used. In certain embodiments, the patellar facets 15 include one or more curvilinear surfaces. In preferred embodiments, the trochlear groove is slightly larger than the corresponding engaging surface of the patella. In certain modalities, the trochlear groove of the femoral implant is moved laterally in relation to the patient's trochlear groove.
5.2 Patella implant component
Certain modalities include a patella implant component containing a specific shape and size of the patient with a domed or elongated topography, 2-4 mm lateralized. A patella component designed in this way can be used to direct weak ML and / or AP adjustments of traditional designs and / or restore the normal topography of the patient's patella. In addition, or alternatively, the thickness of the patella implant can be less than about 11 mm, less than about 10 mm, less than 9 mm, less than about 8.5 mm, about 8 mm, less than about 8 mm, about 7 mm, 30 and / or less than 7 mm.
Certain modalities are aimed at restoring the original thickness of the patient's patella, which can help preserve bone and
75/103 reestablish the patella-femoral kinematics (P-F), for example, by re-establishing the patient's P-F articulation line. Thus, in certain embodiments, the thickness of the patella implant can be combined substantially with the same thickness as the patient's patella.
In certain embodiments, one or more aspects of a patella implant are desired to optimally engage the trochlear groove of a component of the femoral implant. For example, certain embodiments of an implant may include a patella implant component as described in FIGS. 11-1A and 11-1B.
Certain modalities include a patella implant that is non-spheroid in shape, as elongated in shape (i.e., an elongated shape, like a football or lemon), as shown in FIG. 11-2. For example, the upper side of the patella implant can be lemon-shaped so that it has a different medial-lateral versus vertical radius. This design can allow a reduced thickness of the main edges of the implant during flexion / extension.
5.3 Component of the tibial implant
Certain modalities include tibial implant components containing one or more specific or projected aspects of the patient. For example, tibial components can include different middle and lateral cuts of heights. The lateral tibial plateau can be cut 1 or 2 mm higher than the medial tibial plateau. The facet of the tibial lateral plateau of the implant can be 1 or 2 mm higher than the facet of the medial tibial plateau thus moving the bone cut of the tibial lateral plateau 1 or 2 mm higher resulting in more bone preservation. FIGS. 12A and 12B show tibial sections and medial and lateral unicompartmental components with and without a polyethylene layer containing different heights in relation to the tibial plateau.
In certain embodiments, the medial tibial plateau facet can be oriented at a different angle from the facet of the lateral tibial plateau. Typically, each facet of the medial and lateral tibial plateau is at an angle that is specific to the patient, for example, similar to the original inclinations of the medial and lateral tibial plateaus, for example, in the sagittal plane. This is applicable
76/103 to implants that use two unicompartmental components of the tibia, one medium and one lateral. This may be applicable to implant systems that use single components of the tibia, for example, components retaining PCL, posterior stabilized or retaining ACL and PCL. The inclination is preferably between 0 and 7 degrees, but other modalities with other angles of inclination were from that range can be used. The tibial tilt can vary along one or both tibial facets from anterior to posterior. For example, a lower slope, for example, 0 to 1 degree, can be used earlier, and a larger slope can be used later, for example, 4-5 degrees. Variable inclinations through at least one medial or lateral tibial facet can be achieved, for example, with the use of burrs (for example, guided by a robot) or with the use of two or more bone cuts in at least one of the facets tibial. In certain embodiments, two separate slopes are used medially and laterally.
In certain embodiments, the medial and tibial plateau components of the tibia are cut at a different angle. Optionally, the medial and lateral tibia can also be cut at a different distance from the tibial plateau. In this environment, the two cuts of the horizontal tibial plane medially and laterally can have different inclinations and / or can be achieved by one or two vertical cuts, typically positioned medially to the components of the tibial plateau.
The tibial medial plateau component may have a flat, convex, concave, or parabolic surface and / or may have a different thickness than the tibial lateral plateau component. The tibial lateral plateau component may have a flat, convex, concave, or parabolic surface and / or may have a different thickness than the tibial medial plateau component. Different thicknesses can be achieved using a material of different thickness, for example, metal thickness or polyethylene thickness on one side. In certain modalities, the lateral and medial surfaces are selected or designed to resemble the patient's anterior anatomy of the development of the arthritic state.
Certain modalities of tibial trays may have the following
77/103 characteristics, although other modalities are possible: modular insert system (polymer); chromium cobalt mold; white patterns (portions of cobalt and / or modular inert) can be made in advance, then formed specific for the patient to order; thickness based on size (saves bone, optimizes strength); allows 1 or 2-piece insert systems; and / or different media and lateral purposes.
In certain embodiments, the tibial tray is designed or cut white so that the periphery of the tray fits the edge of the cut tibial bone, for example, the combined peripheral geometry of the patient reaches> 70%,> 80%,> 90% , or> 95% cortical coverage. In certain embodiments, the periphery of the tray is designed to have the same shape, but may be slightly smaller, than the cortical area.
Patient-specific tibial implants of certain modalities allow design flexibility. For example, the inserts can be designed to comply with an associated condyle of the femoral device, and can vary in dimensions to optimize the design, for example, one or more in height, shape, curvature (preferably flat to concave), and location of the curvature to accommodate the wear pattern of natural or designed.
5.3.1 Bone cuts for a tibial implant component
In the knee, a tibial cut can be selected so that it is, for example, 90 degrees perpendicular to the tibial mechanical axis or the tibial anatomical axis. The cut can be referenced, for example, by finding the intersection with the lowest middle or lateral point on the plateau.
The inclination for tibial cuts is typically between 0 and 7 or 0 and 8 degrees in the sagittal plane. Rarely, a surgeon can cut the tibia at a steep slope. The tilt can be selected or drawn on a patient-specific cutting template using a preoperative imaging test. The inclination may be similar to the patient's preoperative inclination on at least one on the medial side or one on the lateral side. The medial and lateral tibia can be cut with different inclinations. The inclination can also be similar to the preoperative inclination
78/103 of the patient on at least one on the middle side or one on the side. The height of the tibial cut may differ medially and laterally, as shown in FIGS. 12A and 12B. In some patients, the uncut lateral tibia may be at a different height, for example, higher or lower, than the uncut medial tibia. In this case, the medial and lateral cuts of the tibia can be positioned at a constant distance from a medial and lateral uncut tibial plateau, resulting in different cutting heights medially or laterally. Alternatively, cuts can be made at different distances from the medial and lateral tibial plateau not cut, resulting in the same cut height in the remaining tibia. Alternatively, in this environment, the resulting cut height in the remaining tibia can be chosen to be different medially and laterally.
In certain modalities, a section of the patient's specific proximal tibia (and the corresponding surface that faces the tibial component bone * 15) is designed by: (1) finding the plane of the perpendicular tibial axis (TAPP); (2) reduce the TAPP 2 mm below the lowest point of the medial tibial plateau; (3) tilt the reduced TAPP 5 ° posteriorly (no additional inclination is required on the proximal surface of the insert); (4) fix the inclined rod component at 5 ^o ; and (5) use the Cobb derived tibial anatomical axis for tibial rotational alignment implant. As shown in FIG. 12C, cuts of depths below 2mm, such as 3mm or 4mm, can be drawn, for example, if the bone includes an abnormality in a lower cut cuts the abnormality.
In certain embodiments, a patient-specific proximal cut of the tibia 25 (and the corresponding surface that faces the bone of the tibial component) uses the preceding design except to determine the AP slope of the cut. In certain modalities, a patient-specific AP slope is used if the patient's anatomical slope is between 0 ^o to 7 ^o , a 7 ^o slope is used if the patient's anatomical slope is 30 between 7 ^o and 10 °, and a 10 ° tilt is used if the patient's anatomical tilt is greater than 10 °.
In certain embodiments, a patient-specific A-P slope79 / 103
II • f!
ent is used if the patient's anatomical tilt is between 0 ^o to 7 ^o , a 7 ° tilt is used if the patient's anatomical tilt is above 7 ^o .
In certain embodiments, the axial profile of the tibial implant can be designed to match the axial profile of the patient's tibia cut. FIG. 12D includes additional considerations for tibial implant design. Any of the tibial implant components described above can be derived from a blank that is cut to include one or more aspects specific to the patient.
A patient-specific alignment pin (for example, aligned to the patient's mechanical axis or aligned to the other axis) can be combined with a patient-specific A-P cutting plane. For example, in certain embodiments the peg can be aligned with respect to the patient's sagittal mechanical axis, for example, at a predetermined angle * 15 with respect to the patient's mechanical axis. FIG. 12E shows exemplary A-P and pin angles.
5.3.2 Surface that faces the joint
The surface that faces the joint of a tibial implant component is largely a supporting surface. Like the support surface of the femoral implant described above, a support surface in a tibial implant (for example, a groove or depression in the tibial surface that receives contact with a condyle femoral component) can be of a standard design, for example, available in 6 or 7 different formats, with a single radius or multiple radii in one dimension or more than one dimension.
Alternatively, a support surface can be standardized in one or more dimensions and adapted to the patient in one or more dimensions. Constant and variable radii can be selected in one dimension or multiple dimensions. Some of the rays can be adapted to the patient.
Each of the contact areas of the polyethylene insert of the tibial component and of the implant that engages the surfaces of the medial and lateral femoral condyle can be of any shape, for example, convex, flat, or concave, and can have any radius. In certain modalities, which
80/103 either one or more of the curvatures of the medial or lateral contact areas may include patient-specific radii. Specifically, one or more of the coronal curvature of the medial contact area, the sagittal curvature of the medial contact area, the coronal curvature of the lateral contact area, and / or the sagittal curvature of the contact area may include, at least in part, specific patient rays. In preferred embodiments, the tibial component of the implant is designed to include one or both medium and lateral support surfaces containing the sagittal curvature with, at least in part, patient-specific rays and a standard coronal curvature. Containing, at least in part, sagittal rays adapted to the patient, in turn, can help to achieve normal kinematics with full range of motion. The coronal curvature can be selected, for example, by choosing from a family of standard curvatures to a standard curvature that is more similar to the external rays of the patient's uncut femoral condyle.
In preferred embodiments, the contact area has a standard convex coronal radius that is wider, for example, between 0 and 1 mm, between 0 and 2 mm, between 0 and 4 mm, between 1 and 2 mm, and / or between 2 and 4 mm wider, than the coronal radius in the corresponding femoral component. Using a standard coronal ray in a femoral condyle with a coronal ray negatively fitting or slightly wider or slightly larger in a tibial insert, the wear characteristics of the tibial implant, in this example the polyethylene insert, can be optimized. This approach also has some manufacturing benefits.
For example, a set of different sized tools can be produced where each tool corresponds to a pre-selected standard coronal curvature. The corresponding tool can then be used to produce a polyethylene insert of the tibial component and the implant, for example, to create the curvature in the polyethylene insert. FIG. 13A shows six exemplary tool tips 1310 and a polyethylene insert 1320 in the cross section in the coronal view. The size of the selected tool can be used to generate a polyethylene insert containing a desired coronal curvature. FIG. 13A shows an insert
81/103 of exemplary polyethylene containing two different coronal curvatures created by two different tool tips. The action of the selected tool on the polyethylene insert, for example, a sweeping arc movement through the tool at a fixed point above the insert, can be used to produce a patient-specific or sagittal curvature. FIG. 13B shows a sagittal view of two exemplary tools 1330, 1340 scanning from different distances in a 1350 polyethylene insert of a tibial implant component to create different sagittal curvatures in the 1360 polyethylene insert.
In certain embodiments, one or both areas of tibial contact are a concave groove containing an ascending or descending radius along its sagittal axis, for example, a groove with a descending radius from anterior to posterior.
In certain embodiments, the shape of the concave groove on the lateral and / or medial sides of the surface facing the tibial implant joint is positively fitted by a convex shape on the surface opposite the implant, as shown in FIG. 14A. This can allow the thickness of the component to remain constant, although the surfaces are not flat, and thus can reduce material wear, for example, plastic material such as polyethylene. The constant thickness of the material helps / helps to minimize the thickness of the implant to obtain a certain mechanical resistance. In addition, as shown in FIG. 14A, any corresponding part of the component, such as a metal tray, can also include a groove to engage the curved surface of the plastic material. Two exemplary concavity dimensions are shown in FIG. 14B. As shown in the figure, the concavities or scallops have depths of 1.0 and 0.7 mm, based on coronal geometry of R42.4 mm. At a depth of 1.0 mm, the width of the footprint is 18.3 mm. At a depth of 0.70 mm, the footprint width is 15.3 mm.
EXAMPLES
Example 1 illustrates a process for designing a patient-specific total knee implant. Example 2 describes methods for
82/103 to design and prepare bone cuts for a patient-specific femoral implant component. Example 3 illustrates a femoral component of a total knee replacement containing non-traditional cuts on its internal surface that faces the bone. Example 4 illustrates a patient-specific implant design for an implant containing a femoral component and a patella component. Example 5 illustrates a set of templates to guide patient-specific bone cuts in a first-femur technique. Example 6 illustrates a set of templates to guide patient-specific bone cuts in a tibial first technique. Example 7 illustrates a tibial implant design and cutting technique. Example 8 illustrates a tibial tray and insert design and related templates and cut designs. Example 9 illustrates a finite element analysis (FEA) test conducted on a component of the femoral implant. Example 10 illustrates a device component with an improved articular surface. Example 12 illustrates a design for a tibial implant component. Example 13 illustrates an implant and implant design containing linear and curvilinear bone cuts. Example 14 illustrates an implant and implant design containing regeneration and one or no bone cutting.
Example 1: Exemplary design process for certain patient-specific total knee implants
This example 1 describes an exemplary process for designing a patient-specific total knee implant. The steps described in this design process can be performed in any order and can be performed more than once in a particular design process. For example, steps can be reiterated and refined a second, third, or more times, before, during, or after performing other steps or sets of steps in the design process. While this process specifically describes the steps for designing a patient-specific total knee implant, it can be adapted to design other modalities, for example, patient-specific implants for shoulders and hips.
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Methods
The exemplary design process shown in FIG. Ex 1-1 includes four general steps and, optionally, can include a fifth general step. Each general step includes several specific steps. The general steps are identified as (1) - (5) in the figure. These steps can be performed virtually, for example, using one or more computers that have or can receive specific patient data and appropriate software or instructions to perform these steps.
In the general stage (1), the alignment of the limb and correction of deformities are determined, to the extent that it is necessary for a specific situation of the patient. In the general stage (2), the patient's tibial and femoral dimensions are determined, based on data collected from the patient.
In the general stage (3), bone preservation is maximized by virtually drawing each cut in the femur and tibia. This general step may include one or more of the steps of (i) simulating cuts on one or both articular sides, (ii) applying optimized cuts across both sides, (iii) allowing non-coplanar and / or non-parallel femoral cuts, and (iv) maintain and / or determine minimum material thickness. The minimum material thickness for the implant design can be an established limit, for example, as previously determined by a finite element analysis (FEA) of the standard characteristics and aspects of the implant. Alternatively, the minimum material thickness can be determined for the specific implant, for example, as determined by an FEA of the characteristics and aspects of standard and patient-specific implants. This step dictates for a surgeon the design of the bone resection to be performed in the surgical environment and also dictates the design of the surface facing the implant bone or implants, which can substantially negatively fit the resected bone surfaces.
In the general stage (4), a corrected, normal and / or optimized joint geometry in the femur and tibia is virtually recreated. For the femur, this general step includes one or both steps of (i) selecting a sagittal profile
84/103 pattern or draw a specific sagittal profile of the patient, and (ii) select a standard coronal profile or draw a specific coronal profile of the patient. One or both the sagittal and coronal profiles can optionally have different medial and lateral dimensions. For the tibia, this general step includes one or both steps of (iii) selecting a standard anterior-posterior inclination or drawing a patient-specific anterior-posterior inclination, one of which can optionally vary from medial to lateral sides, and (iv) select a standard poly-articular surface or design a specific polyarticular surface for the patient. The specific surface of the polyarticular patient can be designed, for example, to simulate the normal or optimized three-dimensional geometry of the patient's tibial articular surface. This step contributes to the design on the external articular surfaces that face the joint of the implant or implants.
In the general optional step (5), the virtual implant model is evaluated and can be adapted to achieve normal or optimized normal kinematics. For example, the external or articular surface that faces the joint of the implant or implants can be evaluated and adapted to improve the kinematics. This general step includes one or more of more of the steps of (i) virtually simulating the model's biomovement, (ii) adapting the implant design to achieve really normal kinematics, and (iii) adapting the implant design to avoid potential impact.
Results and discussion
The exemplary design process described above generates one. design of surgical resection to alter joint surfaces of bones during surgery and a design for an implant that specifically fits the patient, for example, following the resection of the designed bone. Specifically, the designed implant, which can be produced or machined to specifications using known techniques, includes one or more surfaces that negatively fit the surface of the resected bone. The implant can also include other design features that are specific to the patient, such as minimum implant thickness, joint geometry, and kinematic design. This design process
85/103 can be applied to various joint implants and to various types of joint implants. For example, this design process can be applied to a total knee implant, cruciform retention, posterior stabilization, and / or ACL / PCL retention.
The exemplary patient-specific design process above, including the resulting patient-specific implants and patient-specific bone resection methods, offers several advantages over traditional primary and revision implants and processes. For example, this allows one or more pre-primary implants so that on subsequent knee replacement or improvement it can take the form of primary knee surgery. Specifically, due to the minimal bone being resected, a subsequent procedure can be performed with a traditional standardized primary knee implant. This offers a significant advantage for younger patients who require one in their lifetime more than a single revision of their knee implants. In fact, the patient-specific exemplary design process described above may allow for two or more pre-primary implants or procedures before bone is lost in which a traditional primary implant is required.
The advantageous minimum resection of the bone and, therefore, minimal bone loss, with this process originates from the fact that the surface that faces the implant bone is designed specifically for the patient. The patient-specific design allows for non-traditional faceted bone cuts that are patient-specific and optimized using any number of cuts to preserve bone for the patient. With traditional implants, bone cuts are standardized and do not take into account the patient's attributes such as, without limitation, the patient's size or weight, joint size, and the size, shape and / or severity of the joint defects.
Another advantage is that the patient-specific design process described above can restore a patient's native normal kinematics, for example, by reducing or eliminating half-fidelity instability.
86/103 of the patient, reducing or eliminating the tight closure, by improving or extending the flexion, improving or reestablishing the aesthetic appearance, and / or creating or improving the normal or expected sensations in the patient's knee. The patient's specific design for a tibial implant allows for a projected surface that replicates the patient's normal anatomy while also allowing low contact stress on the tibia.
For surgeons and medical professionals, the patient-specific design process described above provides simplified surgical technique. The designed bone cuts and projected adjustments of the produced or machined implants eliminate the complications that arise in the surgical environment with traditional implants that lack adjustment.
As noted above, the design procedure may include producing or machining patient-specific implants to specifications determined by the design steps described above. Production may include using a mold designed to form the patient's implant. Machining may include changing a blank shape to conform to the specifications determined by the design steps described above. For example, using the steps described above, the femoral implant component can be produced from a designed mold and the tibial component of the implant, including each of the tibial trays and inserts, can be customized from standard whites.
Example 2: Methods for designing and making bone cuts for a patient-specific implant component.
This example describes two exemplary methods for designing and making bone cuts for two different patient-specific femoral implant components.
In both methods, a model of a distal patient femur is created based on specific patient data collected from one or more three-dimensional images. As shown in FIG. Ex 2-1A, the 2100 epicondylar axis is determined for the patient's femur. Five bone cutting planes and cutting angles are created using the 2100 epicondylar axis. Specifically, four out of five cutting planes - the distal cut, cut
87/103 posterior, posterior chamfer cut, and anterior chamfer cut - are designed to be parallel to the 2100 epicondylar axis. FIG. Ex 2-1A shows the distal cutting plane 2200 parallel to the 2100 epicondylar axis. The anterior cutting plane is designed to be oblique to the 2100 epicondylar axis plane, which can minimize the amount of resected bone on the lateral side of the cut. FIG. 2-1B shows an example of an anterior oblique section plane.
For each of the five cutting planes, a maximum optimized depth cut tangent to the bone surface at the angle of each cutting plane is also drawn. The cuts of maximum optimized depths are shown in FIGS. Ex 2-2A - Ex 2-2E. Specifically, in this example, the maximum depth cut is 6 mm for the distal cutting plane (FIG. Ex 2-2A), the anterior chamfer cut plant (FIG. Ex 2-2B), the posterior chamfer cut (FIG. Ex 2-2C), and the posterior section plane (FIG. Ex 2-2D). The maximum depth cut is 5 mm for the previous cutting plane (FIG. Ex 2-2D).
The optimized number of cutting planes, cutting angle planes, and cutting plane depths can be determined independently for each of the medial and lateral condyles. For example, FIGS. Ex 2-2A - Ex 2-2E show an optimized section plane based on the medial condyle. However, FIGS. Ex 2-3A and Ex 2-3B show the cutting plane for the posterior lateral chamfering condyle and posterior lateral condyle cutting plane, which are independently optimized based on patient-specific data for the lateral condyle. This type of independent optimization between condyles can result in a number of cutting planes, cutting plane angles, and / or cutting plane depths that differ between condyles.
The two bone cutting design methods differ in how the five cutting planes are oriented on the epicondylar axis. In the first drawing, shown in FIG. 2-4A, a distal section plane is drawn perpendicular to the 2400 femoral sagittal axis. In the second drawing, referred to as a flexed or flex-fit drawing and shown in FIG. Ex 2-4B, the
88/103 distal section plane is rotated 15 degrees in flexion perpendicular to the sagittal femoral axis. Additional cut plans are thus changed for each drawing method, as shown in FIGS. Ex 2-5A and Ex 2-5B.
FIGS. Ex 2-6A and Ex 2-6B show the completed femur cut models for each cut design. For each drawing, the maximum resection depth for each cutting plane was 6 mm. The flex-fit design can provide more posterior coverage at high flexion. However, it may still require more resection of the anterior bone to achieve sufficient coverage and may require particular attention during actual cutting to avoid incomplete removal of bone in the 2600 trochlear notch. In certain embodiments of a bone cutting design method, the anterior cutting plane diverges from the axis of the bolt component by five degrees each, as shown in FIG. Ex 2-7A. with a traditional component of the femoral implant, the posterior and anterior cut plane diverges 2 degrees and 7 degrees, respectively, from the axis of the pin. In addition, in certain embodiments, the pin can be designed to have several dimensions. For example, the drawing in FIG. Ex 2-7B includes a pin diameter of 7 mm tapering to about 6.5 mm, a length of 14 mm with a rounded tip, and a base with a 1 mm fillet 2700.
The component resulting from the design of the femoral implant for the method of the first design is shown in FIGS. Ex 2-8A and Ex 2-8B. In addition to the optimized section plane described above, this design also includes a 0.5 mm peripheral margin from the edge of the cut bone. The design also includes coronal curvatures projected in the condyles. The resulting component of the femoral implant designs for the first and second design methods are shown side by side in FIGS. Ex 2-9A and Ex 2-9B. The sagittal view of the figures shows the difference in the anterior and posterior coverage for the two component drawings.
As mentioned above, bone cut optimization can result in a cut design that has any number of cut planes, cut plane angles, and cut plane depths. The desired optimization parameters may include, for example, one or
89/103 more than: (a) correction of deformity and limb alignment (b) maximum preservation of bone, cartilage or ligaments, and (c) restoration of joint kinematics. Additional parameters that can be included in the design process may include one or more of (d) implant shape, external and internal, (e) implant size, (f) implant thickness, (g) location of the joint line, and (h) localization and preservation of particular characteristics of the patient's biological structure, such as the trochlea and trochlear shape.
Example 3: Design of a femoral component of a total knee replacement with the bone-facing surface that optimizes bone preservation
This example describes an exemplary design of femoral components for a total knee replacement implant. In particular, the exemplary design and implant include a femoral component containing seven cuts on the inner surface that faces the bone.
Methods
A femoral implant component (PCL retention) is designed with seven bone cuts for a first femur technique. The design is described in FIG. Ex 3-1 as a virtual model. The design includes seven cuts on the inner surface that faces the bone. The seven cuts include a distal femoral cut that is perpendicular to the sagittal femoral axis, and an anterior cut that is not oblique. The corresponding bone cutting angles are shown in FIG. Ex 3-2A and in FIG. Ex 3-2B. Specifically, anterior cuts are at 25 degrees, 57 degrees, and 85 degrees from the distal femoral cut, as shown in FIG. Ex 3-2A. Posterior sections are at 25 degrees, 57 degrees, and 87 degrees from the distal femoral cut, as shown in FIG. Ex 3-2B. The femoral implant component also includes on a surface that faces the bone cement cuts that are 0.5 mm deep and offset from the outer edge by 2 mm, and a pin protruding from each of the lateral bone cutting sections. and medial distal on the internal surface of the component. The dowels are 7 mm in diameter, 17 mm long and are tapered to 0.5 degrees as they extend from the make
90/103 nente. FIG. Ex 3-3 shows the cement pocket and pin characteristics.
3.2 Results and discussion
In a traditional component of the femoral implant, the surface that faces the bone consists of five standard cuts. However, the femoral component in this example includes seven cuts on a surface that faces the bone. The additional cuts allow for greater implant thickness at the intersection of the cuts and therefore less bone removal than is required by a traditional component of the femoral implant. The external articulation surface of the component may have specific aspects for the patient and / or standard aspects.
FIG. Ex 3-4A and FIG. 3-4B show models of bone cuts with corresponding bone volumes for a model containing five bone cuts for the articular femoral surface (FIG. Ex 3-4A) and for a model containing seven bone cuts for the articular femoral surface ( FIG 3-4B). As shown, the model containing five bone cuts corresponds to a volume of 103.034 mm ³ , while the model containing seven bone cuts corresponds to a volume of 104.220 mm ³ of bone.
As a means of comparison, FIG. Ex 3-5A and FIG. 3-5B show virtual models of bone cuts with corresponding bone volumes for a model containing five bone cuts for the articular femoral surface (FIG. Ex 3-5A) and for a model containing five flexed bone cuts for the femoral surface articular (FIG. Ex 3-5B). As shown, the model containing five, non-flexed cuts of bones corresponds to a volume of 109.472 mm ³ , while the model containing five, flexed cuts of bones corresponds to a volume of 105.760 mm.
FIG. Ex 3-6A - Ex 3-6D shows general lines of a traditional femoral component (in fine lines) overlaid with, in FIG. Ex 3-6A, the model containing seven bone cuts for the articular femoral surface; in FIG. Ex 3-6B, the model containing five, bone cuts for the articular femoral surface; in FIG. Ex 3-6C, the model containing five, non-flexed cuts of bones to the articular femoral surface; and in FIG. Ex 3-6D, the model containing five, flexed cuts of bones to the female surface
91/103 articular ral. As shown in each of these figures, the bone cuts designed save bone substantially when compared to those required by the traditional implant component.
In summary, the exemplary component designs described in this example can save bone when compared to a traditional implant component and thus allow the implant to be pre-primary. The alignment of cuts can also be specific for the patient, for example, symmetrical or asymmetric, parallel or non-parallel, aligned perpendicular to the sagittal or non-perpendicular plane, varied from medial to lateral condyle, etc. The section design can also be flexed (that is, rotated or compensated in relation to the biomechanical or anatomical axes). The design of the fixing pins can also be flexed in relation to the biomechanical or anatomical axes.
Example 4: A trochlear design designed specifically for the patient
This example describes a patient-specific trochlear design that is optimized for the appropriate kinematics of the patella-femoral (PF) joint.
4.1 Method
FIG. Ex 4-1A - Ex 4-1E shows an exemplary design of a knee implant, including a femoral component and a patella component, with a region of disc material highlighted in red in certain figures. Patella placement and material removal were as follows: As shown in FIG. Ex 4-1A, the flat bone support surface of the 4100 patella, was made in parallel to the 4110 epicondylar axis in the coronal view. As shown in FIG. Ex 4-1B, the center plane of the patella implant was made collinear with the 4120 epicondylar axis. This allows general positioning in the peak area of the trochlea. As shown in FIG. Ex 4-1C, in this position the medial-lateral center of the trochlea is identified 4130, and the patella implant component is brought down so that the lowest points are 4140. As shown in FIG. Ex 4-1 D, the patella profile is scanned along with the sagittal curve of the 4150 trochlear region.
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4.2 Results and discussion
This exemplary implant design used a patient-specific sagittal curvature and a coronal curvature designed to allow the patella component to properly follow the trochlear sulcus. This exemplary implant design for the femoral component and a patella component can provide several advantages including a reduction in lateral overfilling of the PF joint and a post-operative patella tracking that is normal or close to the preoperative and / or pre-disease state of the patient. In certain modalities, the lateral peak can be retained, which can minimize the events of minimize displacement. In certain embodiments, the support surface of the patella implant may be or appear to be approximately parallel to the osteochondral joint of the native patella.
Example 5: Bone cuts using a first femur template set
This example describes methods and devices for making a series of bone cuts to receive a specific implant for the patient. Specifically, a set of templates is designed in relation to the design of a patient-specific implant component. The designed templates guide the surgeon in making one or more patient-specific cuts to the bone so that the surface of the cut bone negatively fits the patient-specific bone cuts of the implant component. The set of templates described in this example is designed for a technique of cutting the femur first.
In a first step, shown in FIGS. Ex 5-1A and Ex 5-1B, a first femur template is used to establish the pin and pin placement holes for a subsequent template for a distal cut. In this example, the first template is designed to outline 3 mm of cartilage thickness. In a second step, shown in FIGS. Ex 52A and Ex 5-2B, the distal cut is performed with a second femur template. In this example, the second template is patient-specific. However, in certain modalities that apply a traditional distal cut, a standard template can be used. In a third step, as shown in FIGS. Ex 5-3A, the front cut, the back cut and the chamfer cuts are
93/103 performed with a third femur template. In this example, the template includes grooves that are 1.5 mm wide to allow for a saw blade thickness (ie without metal guides). For implant component designs containing six or more internal surfaces that face the bones, for example, containing one or two additional chamfer cuts, additional cuts can be made using one or more additional templates, for example, as shown in FIG. Ex 5-3B. In this example, the additional template is designed to accommodate two additional steps of chamfer cuts.
Then, the tibia is cut using one or more templates designed to cut into the patient's specific tibia. An exemplary tibial template is described in FIGS. Ex 5-4 and Ex 5-5. A 5400 tibial alignment pin is used to help guide the template properly. The 5410 portion of the template inserted between the femur and the tibia can be of varying thickness. In certain embodiments, the tibial template can be designed to accommodate the thickness of the composite of the distal 5420 femur cut. Alternatively or in addition, a 5600 balance chip can be used to target differences in distance between the tibial and femur surfaces. For example, in certain modalities a tibial template can be designed to rest 2 mm of cartilage, while a balance chip is designed to rest the distal cut of the femur.
A balance chip is shown in FIG. Ex 5-6. If a varus deformity of the knee is observed, the virtual realignment can be targeted including thickness added to the balance chip in the area that could produce a leg in the neutral alignment 5610. For a grossly misaligned contralateral leg, correction can be at the surgeon's order . The balance chip can include a 5620 aspect to join it to the tibial template, and thus allow for the precise distal placement of the tibial cut while at the same time accommodating for the thickness of the composite. An example of a balance chip attached to the tibial template is shown in FIGS. Ex 5-7A and Ex 5-7B. To facilitate connection, the handle of the 5700 balance chip fits the tibial tilt drawn in the tibial cut and the implant
94/103 tibial. Preferably, the balance chip is designed to enter the joint easily.
Example 6: Bone cuts using a set of first tibia template
This example describes methods and devices for making a series of bone cuts to receive a specific implant for the patient. Specifically, a set of templates is designed in relation to the design of a patient-specific implant component. The designed templates guide the surgeon in making one or more patient-specific cuts to the bone so that the surface of the cut bone negatively fits the patient-specific bone cuts of the implant component. The set of templates described in this example is designed for cuts for a femoral implant component in a first tibial cutting technique.
In a first step, shown in FIG. Ex 6-1, a first template is used to establish the positioning and alignment of the pin holes of the femoral implant. In the example, the positioning is flexed 5 degrees with respect to the sagittal femoral axis. In a second step, shown in FIG. Ex 6-2, a second template is used to establish positioning pins for the distal cutting template. The second template can have different thicknesses 6200 to accommodate the thickness of the composite of the tibial cutting surface. In a third step, as shown in FIG. Ex 6-3, a distal cutting template is positioned in the position established by the previous template. The distal cutting template can be patient-specific or standard. Finally, as shown in FIG. Ex 6-4, the remaining cuts are made with a chamfer cutting template. In the example, the previous cut is not oblique.
Example 7: Tibial implant design and bone cuts
This example illustrates the tibial implant components and related drawings, as described in FIGS. Ex 7-1A - Ex 7-3C. This example also describes methods and devices for making a series of tibial bone cuts to receive a tibial implant component, as described and shown in FIGS. Ex 7-4A - Ex 7-5.
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Example 8: Tibial tray designs and inserts
This example illustrates the implant designs and components for tibial trays and inserts, as described in FIGS. Ex 8-1A - Ex 8-3E.
Example 9: Finite element analysis
This example illustrates a finite element analysis (FEA) that can be conducted on a device component of some modalities as a parameter in an optimization of patient-specific aspects of the implant. Specifically, this example describes FEA conducted in three variations of a component of the femoral implant.
9.1 Methods
This analysis investigates the effect of interference adjustment and loading scenarios on three different large geometries of the knee femoral implant component: (a) a component with six bone cuts and a distal perpendicular bone cut (Perp 6-Cortes); (b) a component with five bone cuts and a distal perpendicular bone cut (Perp 5-Cortes); and (c) a component with six bone cuts and flexed bone cuts (6-Flexed Flexes), as shown in FIG. Ex 9-1A. The three knee femoral implant component geometries tested represent implants for the largest expected anatomy, as shown compared to a traditional large implant in FIGS. Ex 9-1B1, Ex 9-1B2, and Ex 9-1B3. The target results included the identification of major stresses and maximum displacements. For a general reference in the conduction of FEA in knee implant components, see Initial fixation of a femoral knee component: an in vitro and finite element study, Int. J. Experimental and Computational Biomechanics, Vol 1, No. 1,2009.
FIG. Ex 9-1C shows set-up information for the test. For initial runs of the three variations, the femur models were installed with 0.35 degrees of interference adjustment angles on the anterior shield surfaces (A, FIG. Ex 9-1), the most medial upper condyle (B, FIG. Ex 92), and upper lateral condyle (C, FIG. Ex 9-2). This angle was adjusted by the iterative analysis of the run until a Main Tension Max of grains
96/103 only 240 MPa (the CoCr fatigue strength limit) can be achieved. The secondary analysis runs were carried out without any interference adjustment in the three femoral implant geometries.
All contact surfaces between the implant and femur (D, FIG. Ex 9-3) were adjusted as frictional (0.5 coefficient of friction based on the general reference described above), and the surfaces between the implant and support plates of condyle (E, FIG. 9-3) were frictionless.
In all cases, the upper face of the femur (F, FIG. Ex 9-4) was completely fixed. The lower faces of the condyle support plates (G and H, FIG. 9-5) were fixed in all directions or, when the load was applied, allowed movement along the femoral axis only (direction Z shown in the visible coordinate).
Loads of 1601 N (360 Ibs.) To the lateral condyle support plate and 2402 N (540 Ibs.) To the middle condyle support plate were applied in the direction of the Femoral Axis (Z axis shown, FIG. Ex 9-6). A balance was reached to align the model's performance with the areas of different contact and results. The general network is shown in FIG. Ex 9-7. The implant component network has been refined for better results in areas of high stress (FIG. Ex 9-8).
9.2 Results and Discussion
The three different geometries of the large component of the knee femoral implant that were evaluated were dimensioned to correspond to the large anatomical knees. The results for No Load Interference, More Load Interference, and No Load More Interference, are shown in Table Ex 9-1 below. The corresponding high voltage locations (identical for all three models) are shown in FIGS. Ex 9-9, Ex 9-10, and Ex 9-11. This data can be used in the design of patient-specific implant components, for example, to identify a minimum component thickness for high stress areas. As shown in the table, there was a 24% reduction in tension with 6 cuts compared to five cuts (221 MPa versus 292 MPa, interference plus no load).
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Table Ex 9-1
Per-6-Cortes Per-5-Cortes Flexed-6-CutsInterference Infer + Car ga S / In rf + Ca rga Interference Infer + C arga S / Interf + Load Interference Infer + C arga S / Interf + Load Max Voltage. Main (Mpa) 246.0 221.0 98.1 241.3 292.0 120.5 261.4 214.0 83.5Decline (mm) Decline (mm) Decline (mm) Lateral Condyle 0.11 0.11 0 0.10 0.10 0 0.11 0.11 0 Mediai condyle 0.08 0.08 0 0.07 0.08 0 0.07 0.07 0 Previous Shield 0.18 0.19 0.05 0.17 0.18 0.05 0.20 0.21 0.05
Example 10: A femoral component device with improved joint surface
This example illustrates an exemplary device component with an improved articular surface. FIG. Ex 10-1A is a schematic front view of the engagement points of a knee implant 10. FIG. Ex 101B is a schematic cross-sectional view in the coronal plane of a femoral component 20 of the implant 10 of FIG. Ex 10-1 A. With respect to FIG. Ex 10-1A and FIG. Ex 10-1B, this exemplary embodiment of a patient-specific implant 10 includes a femoral component 20 and a tibial tray component 30, and this is designed based on specific patient data. An internal surface facing the bone 40 of the femoral component 20 conforms to the corresponding surface of the femoral condyle. Alternatively, it can conform to one or more bone cuts optimized in the femoral condyle. However, the articular outer surface 50 of component 20 is improved to incorporate a smooth surface surface containing an approximately constant radius in the coronal plane. The corresponding articular surface 70 of the tibial tray 30 has a surface contour in the coronal plane that is combined with the external articular surface 50. In this embodiment, the articular surface 70 has a radius that is five times the radius of the external articular surface 50. In certain modalities, the articular surface 50 of component 20 incorporates a sagittal curvature that positively fits the patient's existing or healthy sagittal radius.
FIG. Ex 10-2A - Ex 10-2D shows schematic section views
98/103 transverse on the coronal piano of the respective altered modalities of a femoral component.
The implant design 10 has several advantages. First, the design of the articular surface 50 allows the thickness of the femoral component to be better controlled as desired. For example, referring to FIG. Ex 10-2A, if a curve of an articular surface 80 of a femoral component 90 is too large, the thickness of the femoral component can be very thick along with the centerline 100 of the implant, thus requiring an excessive amount of bone to be removed when the implant is placed in the femoral condyle. On the other hand, referring to FIG. Ex
10-2B, if the same curve 80 is applied to a device containing an appropriate centerline thickness 110, the margins or side walls 120 and 130 of the device may be too thin to provide support for the appropriate structure. Likewise, referring to FIG. Ex 10-20, if the curve of the external articular surface 120 of a femoral component 130 is too flat, the device does not taper from a center line 140 to the margins or side walls 150 and 160 of the device and may not work well.
Again referring to FIG. Ex 10-1A and FIG. Ex 10-1B, a second advantage of implant 10 over certain other modalities of patient-specific devices is that the smooth articular surface 50 is believed to provide better kinematics than a true representation of the surface of the patient's femoral condyle can provide.
For example, referring further to FIG. Ex 10-2D, a method of creating patient-specific implants is to use simple compensation, in which a femoral component 170 is designed using standard compensation from each point on the modeled surface of the patient's femoral condyle. Using said design, the thickness of the device remains essentially constant, and an external surface 180 essentially positively fits or conforms to the underlying surface that faces the internal femoral 190, as well as the modeled surface of the femoral condyle on which it is based. While this provides a positive external surface
99/103 is truly combined with the patient, it is not necessarily optimal for the kinematics of the resulting implant, due to, for example, rough areas that can produce a larger, more localized load on the implant. Using a smooth surface with an essentially predetermined shape, implant loading can be better managed and distributed, thus reducing wear on a tibial tray component 30.
The third advantage, which is also related to the loading and general kinematics of the implant, is in the negative combination of the tibial articular surface 70 to the articular femoral surface 50 in the coronal plane. By providing a radius that is predetermined, for example, five times the radius of the femoral articular surface 50 in its center line in the present embodiment, the loading of the articular surfaces can be further distributed. Thus, the general function and movement of the implant is improved, as is the wear on the tibial tray, which is polyethylene in this modality. While the present modality uses a five-fold proportion of the outer surface at its center line (note that the radius of the outer surface may be slightly different elsewhere on the outer surface 50 outside the center line), other modalities are possible, including an external tibial surface that, in the coronal plane, is based on other proportions of curvature, other curvatures, other functions or combinations of curves and / or functions at various points. Additionally, while the modalities shown in FIG. Ex 10-2A - FIG. Ex 10-2D are not considered to be optimal designs generally, they are modalities that can be generated using automated systems and may have preferential characteristics in some cases.
Example 11: Design of the tibial component of the implant
This example illustrates a design for a tibial implant component, as described more fully in FIGS. Ex 11-1 - Ex
11-7C.
The characteristics of the tibial resection designed in conjunction with the implant component of this example include: axis perpendicular to the tibial; single cut in the posterior medial inclination; and bone cut 2-3 mm
100/103 below the lowest area of the medial tibial plateau.
The characteristics of the tibial component and the implant design in this example include: tray maximizes coverage and extends to cortical margins whenever possible; media compartment coverage is maximized; no protrusion in the middle compartment; prevents internal rotation of the tibial component to avoid patellar dislocation; and avoid excessive external rotation to avoid protruding laterally and impacting the popliteal tendon.
Example 12: Implant and implant design with curvilinear bone cuts
This example illustrates an exemplary implant, implant design, and method for designing an implant containing both linear and curvilinear bone sections. Specifically, a femoral implant is designed to include 3 mm of curvilinear cut depths and corresponding implant thickness along with the distal portion of each condyle. The depth of cut and thickness of the implant together with each condyle are drawn independently of the other condyle. In addition, templates for making curvilinear cuts to the articular surface of the bone are described.
Using a computer model generated from patient-specific data, anterior and posterior cut lines are created in the model, as shown in FIGS. Ex 12-1A and 12-1B. To draw the curvilinear cut line in the middle condyle, a middle separation line is identified in the condyle, as shown in FIG. Ex 12-2A, and then a 3 mm deep cut line is generated to accompany the separation line, as shown in FIG. Ex 12-2B. The resulting virtual curvilinear section is shown in FIG Ex 12-2C. The same steps are performed independently for the lateral condyle, as shown in FIGS. Ex
12-3A-12-3C.
The resulting section model, as shown in FIG. Ex 124A can be used to design the bone-facing surface of the corresponding patient-specific implant, as shown in FIGS. Ex 12-4B and 12-4C. Specifically, the internal surface that faces the implant bone is designed and engineered to substantially fit negates
101/103 to the cutting surface on the model. Optionally, and as shown in the figures, the external surface that faces the implant joint can also be designed and designed to include one or more aspects specific to the patient.
The resulting cutting template can also be used to design one or more cutting templates that are fitted to the bone to guide the bone cutting procedure. For example, FIG. Ex 12-5A shows a model of a bone after being resected using a template that allows sagittal cutting of the bone along the specific J curve for a particular patient's anatomy. FIGS. Ex 12-5B and 12-5C shows an alternative set of jigs that can be used with a router type saw. Specifically, a rotary drill can be fitted in the central channel of the template shown in FIG. Ex 12-5B to cut along with the channel to a specific depth, for example, 3 mm. Then, as shown in FIG. Ex 125C, a second template containing two channels that bypass the channel of the first template can be applied. The router type drill can fit in these two channels to cut medium and lateral to the first channel at the same depth, for example, 3 mm.
FIG. Ex 12-6A shows a bone model prepared after template guided bone cuts. FIG. Ex 12-6B shows the model of FIG. Ex 12-6A with a specific two-piece implant for the patient designed with an internal surface that faces the bone that substantially negatively fits the surface of the cut bone.
Example 13: Implant and implant design with regeneration
Example 13 illustrates an implant and implant design containing a regenerated part and a cut bone part and an implant and implant design containing a regenerated surface without bone cuts.
Using a patient-specific computer model generated from patient-specific data, a femoral implant is designed to include a single posterior cut on the inner surface that faces the bone, as shown in FIGS. Ex 13A-4E above and in FIGS. Ex 131A and 14-1B. The remaining portions of the internal surface that faces the bone of the
102/103 implants are designed to substantially negatively fit the articular surface of the bone that it engages. Optionally, the external surface facing the implant joint can also be designed to include one or more aspects specific to the patient. As shown in the figures, the patient-specific implant with a single bone cut is prepared as two pieces or components, which allows adjustment to the portion anterior to the implant curve 1390 around the anterior portion 1392 of the femur.
The design of the femoral implant shown in FIGS. Ex 13-2A and Ex 13-2B and the corresponding implant shown in FIG. Ex 13-2C also uses a two-piece or component design, in part to allow adjustment to the curve of the anterior portion of the 1390 implant around the anterior portion 1392 of the femur. Specifically, using a patient-specific computer model generated from patient-specific data, a femoral implant was designed to include no bone cut on its internal surface that faces the bone. On the contrary, the internal surface that faces the implant bone was designed to substantially negatively fit the articular surface of the bone that it engages. Optionally, the external surface facing the implant joint can also be designed to include one or more aspects specific to the patient.
INCORPORATION AS A REFERENCE
The full disclosure of each of the publications, patent documents and other references mentioned here is incorporated here as a reference in its entirety for all purposes to the same extent as if each individual source were individually denoted as being incorporated as a reference.
EQUIVALENTS
The invention can be carried out in other specific ways without departing from the spirit or essential characteristics of it. The aforementioned modalities are therefore considered in all cases to be illustrative rather than limiting. The scope of the invention is then indicated
103/103 by the appended claims rather than by the description above, and all changes that fall within the meaning and equivalence range of the claims are intended to be encompassed in this document.

权利要求:
Claims (10)
[1]
1. Patient-specific femoral implant for implantation in a portion of a patient's knee femur, comprising:
a condylar portion having a bone-facing surface to touch at least a portion of a condyle of the patient's knee and an articular surface generally opposite to the bone-facing surface;
characterized by the fact that the articular surface has a patient-specific curvature generally arranged in the foreground, the patient-specific curvature substantially replicating a corresponding curvature of at least a portion of the patient's condyle and being located at approximately the same location as the curvature corresponding to the patient's condyle when the surface facing the bone touches the condyle; and the articular surface has a constant curvature in a second plane that is generally transversal to the first plane.
[2]
2. Implant according to claim 1, characterized in that the specific curvature of the patient extends substantially along the entire length or a portion of the length of the articular surface or in which the specific curvature of the patient extends along the majority of the length or a portion of the length of an area that supports the weight of the implant.
[3]
3. Implant, according to claim 1, characterized by the fact that the first plane is a sagittal plane and the second plane is a coronal plane.
[4]
4. Implant according to claim 1, characterized by the fact that the specific curvature of the patient substantially matches a corresponding curvature of the patient's condyle, approaches a corresponding curvature of the patient's condyle, or is a smoothed curvature that eliminates or it reduces at least some local maximum of a curvature of the patient's condyle.
[5]
5. Implant, according to claim 1, characterized by
2/3 the fact that the constant curvature extends substantially along the entire length of the articular surface, over a portion of the length of the articular surface, or over a portion of the length of an area that supports the weight of the implant.
[6]
6. Implant, according to claim 1, characterized by the fact that the constant curvature approaches an average curvature of a corresponding curvature of the patient's condyle or in which the constant curvature is a standardized curvature.
[7]
7. Implant, according to claim 1, characterized by the fact that it still includes a second condylar portion having a surface facing the bone to touch at least a portion of a second condyle of the patient's knee.
[8]
8. Femoral implant having at least one of a medial condyle and a lateral condyle with a surface facing the condylar bone and a condylar articular surface, characterized by the fact that the condylar articular surface comprises:
(a) a condylar articular surface curvature in a foreground derived from patient-specific data and designed to match a corresponding surface curvature of the patient's anatomy, or a predetermined percentage of it, over at least a portion it carries weight of the condylar articular surface; and (b) a condylar joint surface curvature in a second plane that is engineered or selected to be constant over at least a portion that carries weight from the condylar joint surface.
[9]
9. Femoral implant according to claim 8, characterized by the fact that it still comprises one or more additional implant characteristics or measures derived from specific patient data and adapted for the particular patient.
[10]
10. Femoral implant according to claim 8, characterized by the fact that one or more of additional features or measures include:
3/3
a) one or more planar facets on the surface facing the bone of the femoral implant being derived from patient specific data and adapted to maximize bone preservation for the particular patient;
b) a condylar width of the implant being derived from specific patient data and adapted to substantially match a corresponding width of the patient's femoral condyle, or a predetermined percentage thereof;
c) a distance between the medial and lateral condyles in the implant being derived from patient-specific data and adapted to substantially match a corresponding distance between the patient's medial and lateral femoral condyles, or a predetermined percentage thereof;
d) an implant thickness from the bone-facing surface to the articular surface being derived from the patient-specific data and adapted to substantially match a corresponding thickness of a planned resection cut surface to a corresponding articular surface in the patient's femur, or a predetermined percentage of it;
e) a transverse perimeter shape of the implant being derived from specific patient data and adapted to substantially match a corresponding transverse perimeter shape of the patient's femur, or a predetermined percentage thereof; or
f) a volume of a portion of the implant derived from patient-specific data and adapted to substantially match a corresponding volume of a portion of the patient's femur, or a predetermined percentage of it.

类似技术:

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同族专利:

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公开号 | 公开日

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CN102711670B|2016-05-25|

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GB2486373A|2012-06-13|

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AU2010289706B2|2015-04-09|

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CA2771573C|2017-10-31|

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WO2011028624A1|2011-03-10|

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IN2012DN01687A|2015-06-05|

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KR20120090997A|2012-08-17|

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EP3000443A3|2016-07-06|

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CN102711670A|2012-10-03|

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EP2470126B1|2015-10-14|

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SG10201405092SA|2014-10-30|

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JP5719368B2|2015-05-20|

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JP2015154942A|2015-08-27|

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KR101792764B1|2017-11-02|

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SG178836A1|2012-04-27|

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EP3000443A2|2016-03-30|

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HK1170652A1|2013-03-08|

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JP6220804B2|2017-10-25|

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JP2013503007A|2013-01-31|

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GB201205265D0|2012-05-09|

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HK1222113A1|2017-06-23|

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AU2010289706A1|2012-03-29|

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BR112012008058A2|2016-03-01|

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CA2771573A1|2011-03-10|

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EP2470126A1|2012-07-04|

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法律状态:
2019-01-08| B06F| Objections, documents and/or translations needed after an examination request according art. 34 industrial property law|

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2019-07-09| B06T| Formal requirements before examination|

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2019-11-05| B09A| Decision: intention to grant|

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2020-01-14| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 26/08/2010, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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US27517409P| true| 2009-08-26|2009-08-26|

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US28049309P| true| 2009-11-04|2009-11-04|

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US28445809P| true| 2009-12-18|2009-12-18|

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PCT/US2010/025459|WO2010099353A1|2009-02-25|2010-02-25|Patient-adapted and improved orthopedic implants, designs and related tools|

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US33976610P| true| 2010-03-09|2010-03-09|

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PCT/US2010/039587|WO2010151564A1|2009-06-24|2010-06-23|Patient-adapted and improved orthopedic implants, designs and related tools|

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PCT/US2010/046868|WO2011028624A1|2009-08-26|2010-08-26|Patient-specific orthopedic implants and models|

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