Method for examining knee anatomy and constructing an anatomical system for revision knee arthroplasty - Patent Application 20070123333

Abstract

A prosthetic system for providing motion between a first and a second bone of a joint is disclosed, the system comprising a support structure (such as a sleeve or cone) having a first end face, a second end face, an outer surface extending from the first end face to the second end face, and an inner surface defining a passageway extending from the first end face to the second end face, the outer surface of the support structure configured to be received within a cavity of the first bone such that the first end face is flush with or recessed from a surface of the first bone, the first end face lies in an axial plane defined by the first end face and an outermost edge of the first end face, and a longitudinal axis of the passageway in the support structure is offset from a geometric center point of the axial plane.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is based on and claims the benefit of U.S. Provisional Application Nos. 63 / 300,412, filed January 18, 2022, and 63 / 331,329, filed April 15, 2022, and claims priority to both provisional applications, the entire contents of which are incorporated herein by reference.

[0002] <Statement Regarding Federally Sponsored Research> none.

[0003] 1. Field of the Invention The present invention relates to a revision total knee replacement component that maximizes contact between the total knee replacement component(s) and the natural bone while minimizing the risk of intraoperative fracture. [Background technology]

[0004] <2. Description of Related Technology> In a total knee replacement, the articulating elements of the knee joint are replaced. During the procedure, the distal end of the femur is cut to a specific shape before a femoral implant is attached. The femoral implant typically has a pair of convex condyle surfaces that can be attached to a femoral stem for additional fixation to the bone. The proximal end of the tibia is also cut to a specific size or shape before a tibial stem is secured to the proximal end of the tibia. If necessary, a tibial stem extension can be used for additional fixation. The femoral condyle surfaces are shaped to slide within a corresponding concave bearing surface in the tibial bearing. The tibial bearing is typically formed from a polymeric material, such as polyethylene, that allows the femoral condyle surfaces to slide within the concave bearing surface with reduced friction. The tibial bearing is attached proximally to the tibial platform.

[0005] In some surgical cases, bone loss occurs in the distal portion of the femur and / or the proximal portion of the tibia. Several techniques have been developed over time to compensate for this lost bone, including the use of metaphyseal sleeve augmentation. Metaphyseal sleeves are attached around the stem extension(s) in femoral and / or tibial implants, contributing to both early and long-term implant fixation in the bone. On the other hand, metaphyseal cones involve first placing the cone in the bone, followed by the independent placement of the femoral and / or tibial components. Both metaphyseal sleeves and metaphyseal cones have been found to be very effective in addressing such bone defects. Furthermore, these devices have been found to be effective in increasing long-term implant fixation.

[0006] Globally, primary and revision knee replacements are experiencing a dramatic increase. Knee replacements are expected to grow 673% to 3.5 million cases per year by 2030, with revision knee replacements expected to exceed 250,000 in the United States alone. One of the major challenges with revision knee replacements is dealing with bone loss resulting from the failure of a previous knee replacement. Looking at existing equipment on the market, significant shortcomings are evident. Specifically, current revision knee metaphyseal sleeves 110, 120 are not anatomically shaped or have an optimized size distribution (see FIG. 1). Furthermore, revision tibial and femoral stems are not always properly positioned relative to the sleeve to engage the central aspect of the diaphyseal canal. This can lead to implant misalignment in the axial, sagittal, and coronal planes, which can negatively impact patient outcomes.

[0007] Testing has revealed that currently available metaphyseal sleeves used to address bone defects during revision knee arthroplasty are all uniformly round or semicircular and do not optimally match the underlying anatomy (see Figures 2A and 2B, which show a tibial tray 210, sleeve 220, and stem 230). Currently available sleeves, and similarly currently available cones, do not account for the individual differences between the medial and lateral sides of the proximal tibia and distal femur (see cones 310, 320, and 340, Figures 3A and 3B). The less contact with the underlying bone, the greater the stresses placed on the instrument-bone interface. This is associated with both significant early loosening and a lack of long-term bone ingrowth. In the surgeon's efforts to maximize native bone contact, there is also a greater tendency for intraoperative fractures to occur when the surgeon forces non-anatomical instruments into anatomical spaces or removes excessive amounts of bone to fit the implant into the patient's bone. Rather than matching the implant to the anatomy, the surgeon is required to match the anatomy to the implant (see tibial component 410 in FIG. 4).

[0008] To achieve the best quality implant with maximum bone contact, implants that match the anatomy of the proximal tibia and distal femur are required. Furthermore, the distribution of available implant sizes must be based on both the actual anatomy and individual left and right implants.

[0009] The need for total knee revision arthroplasty is expected to continue to increase dramatically over the coming decades. During revision surgery, surgeons must achieve durable fixation and ligamentous stability, often in the setting of pre-existing bone loss and ligamentous compromise. Failure to achieve these goals results in a perpetual cycle of implant failure and revision surgery.

[0010] Current revision surgery emphasizes the concept of zonal fixation, aiming to achieve firm fixation at the joint level in the metaphyseal (sleeve or cone) and diaphyseal (cemented or cementless stem). Attempting to optimize zonal fixation can result in a wide range of complications when using non-anatomically correct implants. These include fracture of the tibia and / or femur at the time of implant preparation or implantation, significant premature loosening of components if contact with native bone is not maximized, and / or lack of durable fixation (e.g. bone ingrowth into the metaphyseal cone or metaphyseal sleeve).

[0011] Thus, there exists an unmet need for revision joint replacement components that maximize contact between the component(s) and the natural bone while minimizing the risk of intraoperative fracture. Summary of the Invention

[0012] The above notable limitations of current revision knee replacement components have led to a comprehensive investigation into the causes of the above-mentioned problems, which has resulted in novel methods of addressing these problems.

[0013] The method maximizes contact between the instrument and the native bone while minimizing the risk of fracture. Some conventional sleeves and cones are used with cement due to lack of fit with the underlying bone. Benefits of improved cementless revision knee components include durable long-term implant fixation, reduced operating room time, avoidance of complications associated with the use of cement, and potentially less invasive future revision surgery if required. The method provides an intuitive and streamlined workflow that can greatly improve the surgeon's experience and greatly improve patient care.

[0014] Disclosed herein is a methodology that uses CT scan data and 3D modeling to provide a deep understanding of anatomy and intuitive instrumentation and implant development that greatly facilitates revision knee arthroplasty. The methodology describes the interactions between the anatomical features of the proximal tibia and distal femur and how these vary depending on the specific location of the bone. Furthermore, the methodology has shown that the proximal tibia and distal femur regions are highly bilateral. Thus, by providing bilateral revision implants with anatomical shapes of real patient population-based distribution, the attachment and fit at the bone-instrument interface can be maximized, thereby providing optimal contact of the implant to the viable host bone and maximizing long-term fixation.

[0015] The present invention provides meaningful findings about the anatomy beneath the implant, clearly characterizing that the proximal tibia and distal femur are not uniform. Depending on the specific location of the proximal tibia and distal femur, the underlying architecture and three-dimensional structure vary significantly, differences that have not been adequately accounted for in existing total knee revision procedures.

[0016] In one aspect, the disclosure provides a prosthetic system for providing motion between a first bone and a second bone of a joint, the system comprising a support structure having a first end face, a second end face, an outer surface extending from the first end face to the second end face, and an inner surface defining a passageway extending from the first end face to the second end face, the outer surface of the support structure configured to be received within a cavity of the first bone such that the first end face is flush with or recessed from a surface of the first bone, the first end face lies in an axial plane defined by the first end face and an outermost edge of the first end face, and a longitudinal axis of the passageway in the support structure is offset from a geometric center point of the axial plane.

[0017] In one embodiment of the prosthetic system, the first bone is a tibia and the joint is a knee. The prosthetic system may further include a tibial implant having a body and a stem extending away from the body, the stem being positioned within the passageway of the support structure. The body of the tibial implant may be a tibial tray. The prosthetic system may further include a tibial bearing in contact with the tibial tray, the tibial bearing having a bearing surface for coupling with an articular surface of a femoral component.

[0018] In one embodiment of the prosthetic system, the first bone is the femur and the joint is the knee. The prosthetic system may further include a femoral component having medial and lateral condyles with curved articular surfaces. The prosthetic system may further include a tibial tray in contact with a tibial bearing having a bearing surface for coupling with the articular surface of the femoral component.

[0019] In one embodiment of the prosthetic system, a longitudinal axis of the passageway of the support structure forms an oblique angle with a normal to the axial plane. The oblique angle can be greater than 0 degrees and less than 10 degrees. The oblique angle can be greater than 3 degrees and less than 9 degrees.

[0020] In one embodiment of the prosthetic system, the longitudinal axis of the passage of the support structure is an intramedullary axis having a first intersection point defined by a first intersection of a first reference axial plane located at a first distance from an end face of the first bone before resection with an axis of inertia of the first bone, and a second intersection point defined by a second intersection of a second reference axial plane located at a second distance different from the first distance from the end face of the first bone before resection with the axis of inertia of the first bone. The first distance can be between 25 mm and 125 mm, and the second distance can be between 75 mm and 200 mm.

[0021] In one embodiment, the prosthetic system may further include a prosthetic implant having a body and a stem extending away from the body, the stem being disposed within the passageway of the support structure. In one embodiment of the prosthetic system, the support structure may be a sleeve, and the sleeve may be attached to the stem of the prosthetic implant. In one embodiment of the prosthetic system, the support structure may be a cone.

[0022] In one embodiment of the prosthetic system, the outer surface of the support structure is stepped. In another embodiment of the prosthetic system, the outer surface of the support structure is smooth. In another embodiment of the prosthetic system, the outer surface of the support structure is roughened. In another embodiment of the prosthetic system, the outer surface of the support structure comprises a porous in-growth material.

[0023] In one embodiment of the prosthetic system, the support structure comprises a wall between the outer surface and the inner surface, the wall having one or more notches extending away from the first end surface. In one embodiment of the prosthetic system, the wall is an anterior wall. In one embodiment of the prosthetic system, the wall is a posterior wall.

[0024] In one embodiment of the prosthetic system, the support structure comprises a wall between the outer surface and the inner surface, the wall having one or more notches extending away from the second end surface. In one embodiment, the wall is an anterior wall. In another embodiment, the wall is a posterior wall.

[0025] In one embodiment of the prosthetic system, the support structure comprises a wall between the outer surface and the inner surface, a thickness of an anterior portion of the wall being less than a thickness of another portion of the wall adjacent the anterior portion of the wall. In another embodiment of the prosthetic system, the outermost edge of the first end surface is a periphery of the first end surface. In another embodiment of the prosthetic system, the first end surface has one or more slots extending from the passageway, each slot being sized to receive a stabilizing arm of a stem of a prosthetic implant.

[0026] In another aspect, the disclosure provides a kit for a prosthetic system for providing motion between a first bone and a second bone of a joint, the kit may include: (i) a first support structure having a first end surface, a second end surface, an outer surface extending from the first end surface to the second end surface, and an inner surface defining a passageway extending from the first end surface to the second end surface, the outer surface of the first support structure configured to be received within a cavity of the first bone such that the first end surface is flush with or recessed from a surface of the first bone, the first end surface being within an area defined by an outermost edge of the first end surface; (ii) the kit may further comprise one or more additional support structures each having an end face, the end face of each additional support structure being in an additional axial plane defined by the end face of the additional support structure and a boundary of the end face of the additional support structure, and each longitudinal axis of the passageway passing through each additional support structure being offset from a geometric center point of the additional axial plane.

[0027] In one embodiment of the kit, the first bone is a tibia, the joint is a knee, and the first support structure and the additional support structure are configured to be placed into a cavity in the tibia.

[0028] In one embodiment of the kit, the first bone is a femur, the joint is a knee, and the first support structure and the additional support structure are configured to be placed into a cavity of the femur.

[0029] In one embodiment of the kit, a longitudinal axis of the passageway of the first support structure forms an oblique angle with a normal to the axial plane. The oblique angle can be greater than 0 degrees and less than 10 degrees. The oblique angle can be greater than 3 degrees and less than 9 degrees.

[0030] In one embodiment of the kit, the longitudinal axis of the passage of the first support structure is an intramedullary axis having a first intersection point determined by a first intersection of a first reference axial plane located at a first distance from an end face of the first bone before resection with the inertial axis of the first bone, and a second intersection point determined by a second intersection of a second reference axial plane located at a second distance different from the first distance from the end face of the first bone before resection with the inertial axis of the first bone.

[0031] In one embodiment of the kit, the first support structure and each of the additional support structures are sleeves, each of the sleeves being sized to be attached to a stem of a prosthetic implant.In one embodiment of the kit, the first support structure and each of the additional support structures are cones.

[0032] In one embodiment of the kit, the outer surface of the first support structure is stepped. In one embodiment of the kit, the outer surface of the first support structure is smooth. In one embodiment of the kit, the outer surface of the support structure is rough. In one embodiment of the kit, the outer surface of the support structure comprises a porous in-growth material.

[0033] In one embodiment of the kit, the first support structure comprises a wall between the outer surface and the inner surface, the wall having one or more notches extending away from the first end surface. In one embodiment, the wall is a front wall. In one embodiment, the wall is a rear wall.

[0034] In one embodiment of the kit, the first support structure comprises a wall between the outer surface and the inner surface, the wall having one or more notches extending away from the second end surface. In one embodiment, the wall is a front wall. In one embodiment, the wall is a rear wall.

[0035] In one embodiment of the kit, the first support structure includes a wall between the outer surface and the inner surface, a front portion of the wall having a thickness less than a thickness of another portion of the wall adjacent the front portion of the wall. In one embodiment of the kit, an outermost edge of the first end surface is a periphery of the first end surface. In one embodiment of the kit, the first end surface has one or more slots extending from the passageway, each slot sized to receive a stabilizing arm of a stem of a prosthetic implant.

[0036] In another aspect, the disclosure provides a method for manufacturing a prosthetic support structure for implantation into a cavity in an end of a bone, the method including forming the support structure having an outer surface sized to fit into the cavity and an inner surface defining a passage in the prosthetic support structure, the passage sized to receive a stem of a prosthetic implant, the passage extending from a first end face to a second end face of the support structure, the first end face of the support structure lying in an axial plane defined by the first end face and an outermost edge of the first end face, the passage having a longitudinal axis, an intersection of the axial plane and the longitudinal axis of the passage being located at a first distance from the end face of the reference bone, (i) acquiring an image of a reference bone, (ii) orienting on the image a first reference axial plane located at a first distance from the end face of the reference bone, and (iii) orienting on the image a first reference axial plane located at a first distance from the end face of the reference bone. (iv) orienting an intramedullary axis on the image by connecting a first intersection point determined by a first intersection portion of an inertial axis of the reference bone with the first reference axial plane and a second intersection point determined by a second intersection portion of an inertial axis of the reference bone with the second reference axial plane; (v) orienting on the image a reference resection plane having a boundary determined by the axial image of the reference bone; and (vi) orienting on the image a reference intersection point between the reference resection plane and the intramedullary axis, wherein the reference spatial relationship between the reference intersection point and the boundary of the reference resection plane corresponds to a spatial relationship between the intersection point on the axial plane and the outermost edge of the first end face of the support structure.

[0037] In one embodiment of the method, a longitudinal axis of the passageway of the support structure is offset from a geometric centre point of the axial surface.

[0038] In one embodiment of the method, the bone is a tibia.In one embodiment of the method, the bone is a femur.

[0039] In one embodiment of the method, a longitudinal axis of the passageway of the support structure forms an oblique angle with a normal to the axial plane. The oblique angle can be greater than 0 degrees and less than 10 degrees. The oblique angle can be greater than 3 degrees and less than 9 degrees.

[0040] In one embodiment of the method, the first distance is between 25 mm and 125 mm and the second distance is between 75 mm and 200 mm.

[0041] The method may further include determining a spatial relationship between the intersection point on the axial plane and the outermost edge of the first end surface of the support structure by orienting a radial measurement between the reference intersection point and a boundary of the reference resection surface on an axial image of the reference bone.

[0042] The method further comprises: determining whether a spatial relationship between the intersection point on the axial plane and an outermost edge of the first end surface of the support structure directs an angle measurement between the reference intersection point and a geometric center point of the reference resection surface on an axial image of the reference bone. The determination may be made by:

[0043] The method may further comprise determining a spatial relationship between the intersection on the axial plane and the outermost edge of the first end surface of the support structure by orienting a medial-lateral length measurement between the medial and lateral sides of a boundary of the reference resection surface on an axial image of the reference bone.

[0044] In one embodiment of the method, the support structure is a sleeve, the sleeve configured to be attached to the stem of the prosthetic implant. In one embodiment of the method, the support structure is a cone.

[0045] Advantages of the prosthetic systems, kits and methods disclosed herein include, but are not limited to: The stem is offset within the sleeve / cone, allowing for more anatomical positioning. A wider range of anatomical shapes and sizes of metaphyseal sleeves / cones (i) The technique is much simpler, avoiding the tradeoffs between rotation / translation / size; (ii) it allows for application to a wider range of anatomical structures; (iii) providing the flexibility to choose whether to use a sleeve or cone configuration in the same device; The specific characteristics of the smooth or stepped walls and the specific dimensions can be flexible based on the needs and desires of the customer and the specific final sizes can be redistributed within the prosthetic system or kit disclosed herein. For example, a company may only want to build 4 sleeves instead of 6 sleeves. The specific inner dimensions of the sleeve and cone disclosed herein are flexible, allowing any customer to individually customize their own revision system; Customizable interiors are possible within the sleeve and cone outlines disclosed herein.

[0046] Advantageous configurations of the sleeve and cone of the present disclosure include, but are not limited to: 〇External design and stem offset, * The internal dimensions can be customized to fit the customer's specific implant design. o Models of smooth walled outer sections or stepped walls can be created, which can make the creation of instruments and implants easier and can facilitate use in robotic assisted creation of sleeves / cones.

[0047] These and other features, aspects and advantages of the present invention will become better understood with reference to the following detailed description, drawings and appended claims. [Brief description of the drawings]

[0048] [Figure 1] FIG. 1 shows an anterior x-ray image and a lateral x-ray image of a prior art revision knee prosthesis system provided with a femoral component with a femoral augment in the form of a sleeve and a tibial component with a tibial augment in the form of a sleeve. [Figure 2A-B] A is an anterior view of a prior art tibial component with a tibial augment in the form of a sleeve, and B is another anterior view of a prior art tibial component with a tibial augment in the form of a sleeve. [Figure 3A-B] FIG. 1A is a perspective view of a tibial augment in the form of a cone, and FIG. 1B is a top view of a prior art tibial augment in the form of a cone implanted on the proximal end of the tibia. [Figure 4] FIG. 1 shows an anterior (panel a) and lateral (panel b) x-ray images of another prior art revision knee prosthesis system provided with a femoral component and a displaced tibial component with a tibial augment in the form of a sleeve. [Diagram 5] FIG. 1 shows an anterior coronal image of the tibia, including the measurement lines of the present invention from the tibial lateral cortical plateau to the cancellous bone at points on the plane 50 millimeters (mm) and 100 mm distally. [Figure 6] FIG. 1 shows an anterior coronal image of the tibia, including a reference tibial resection surface indicating the location of a standard tibial cut to create a tibial resection surface for a total knee arthroplasty. [Figure 7A-B] 7A shows an axial slice of an image of a tibia including the measurement line of the present invention, where the geometric center point is defined as the center of gravity of the slice and the distance from the intramedullary (IM) axis point to the geometric center point is measured, and B shows an anterior coronal image of a tibia including the measurement line of the present invention in an axial slice 5 mm away from the reference tibial resection surface shown in FIG 6 to a distance of 50 mm distal to the reference tibial resection surface shown in FIG 6, where on the right side of FIG 7B is the geometric center point shown in FIG 7A and on the left side of FIG 7B is the intramedullary axis point shown in FIG 7A. [Figure 8]FIG. 7B shows an axial slice of an image of a tibia including a measurement line of the present invention, in which the measurement of the angle between the line intersecting the intramedullary axis point and the geometric center point of FIG. 7A and the medial-lateral axis is the angular deviation. [Figure 9] FIG. 2 shows an axial slice of an image of a tibia including a measurement line of the invention, the measurement line passing through the geometric midpoint of the anterior-posterior width and the geometric midpoint of the medial-lateral width. [Figure 10] FIG. 7 shows an axial slice of an image of a tibia including a measurement line of the present invention, in which radial measurements are made based on the intramedullary axis point of FIG. 7A of the slice, and the distance from the intramedullary axis point to the edge of the tibia of the slice is measured every 5 degrees clockwise on the anterior, lateral, posterior and medial sides. [Figure 11] 6 is a table showing the maximum medial-lateral widths of the reference tibial resection plane shown in FIG. 5, with the proximal tibias arranged in groups of 4 mm each. The tibias are grouped by width, with 54-58 mm, 58-62 mm, 62-66 mm, 66-70 mm, 70-74 mm, 74-78 mm, and 78-82 mm. [Figure 12A] FIG. 12 is a graph showing the total distance between the intramedullary axis point in FIG. 7 and the geometric center point in FIG. 7 at 10 mm intervals from the reference tibial resection plane shown in FIG. 5 when moving along the tibia from proximal to distal for all groups in FIG. 11 . [Figure 12B] 8 is a graph showing the total distance between the intramedullary axis point in FIG. 7 and the geometric center point in FIG. 7 at 10 mm intervals from the reference tibial resection plane shown in FIG. 5 when moving along the tibia from proximal to distal for the overall average. [Figure 13A] FIG. 12 is a graph showing the average deviation between the intramedullary axis point in FIG. 7 and the geometric center point in FIG. 7 at 10 mm intervals from the reference tibial resection plane shown in FIG. 5 for all groups in FIG. 11 as moving along the tibia from proximal to distal. [Figure 13B]FIG. 8 is a graph showing the average deviation between the intramedullary axis point in FIG. 7 and the geometric center point in FIG. 7 at 10 mm intervals from the reference tibial resection plane shown in FIG. 5 when moving along the tibia from proximal to distal for the overall average. [Figure 14A] 12 is a graph showing the angular deviation of the angle between the line intersecting the intramedullary axis point in FIG. 7 and the geometric center point in FIG. 7 and the medial-lateral axis when moving from proximal to distal along the tibia up to 50 mm at 5 mm intervals from the reference tibial resection plane shown in FIG. 5 for all groups in FIG. 11 . [Figure 14B] 8 is a graph showing the angular deviation of the angle between the line intersecting the intramedullary axis point in FIG. 7 and the geometric center point in FIG. 7 and the medial-lateral axis when moving from proximal to distal along the tibia up to 50 mm in 5 mm intervals from the reference tibial resection plane shown in FIG. 5 . [Figure 15] 12 is a graph showing the radial measurement results of FIG. 10 for each group of FIG. 11. [Figure 16] FIG. 1 shows a medial sagittal image of a femur including measurement lines of the present invention from the medial distal end surface of the femur to the cancellous bone at points 75 millimeters (mm) and 175 mm proximally. [Figure 17] 1 is an anterior coronal view of an image of a femur including measurement lines of the present invention for medial-lateral width. [Figure 18] FIG. 1 shows an axial slice of an image of a femur including a measurement line of the present invention, where the geometric center point is defined as the centroid of the slice and the distance from the intramedullary (IM) axis to the geometric center point is measured. [Figure 19] FIG. 17 shows a lateral sagittal image of the femur including an axial slice referenced to the intramedullary axis point of FIG. 16. [Figure 20A-B](A) shows an axial slice of an image of a femur including a measurement line of the present invention, where radial measurements are made based on the intramedullary axis of the slice in FIG. 18, and the distance from the intramedullary axis to the edge of the slice is measured every 5 degrees clockwise on the anterior, lateral, posterior and medial sides. (B) shows an anterior coronal view of an image of a femur including a reference femoral resection plane indicating the location of a standard femoral cut to form a femoral resection plane for a total knee arthroplasty. [Figure 21] 17 is a table showing the maximum medial-lateral widths of the reference femoral resection plane shown in FIG. 16, with the distal femurs arranged in groups of 5 mm each. The femurs are grouped by width into a 65-70 mm group, a 71-75 mm group, a 75-80 mm group, a 80-85 mm group, and a 80 mm or wider group. [Figure 22] 22 is a graph showing the total distance between the intramedullary axis point in FIG. 18 and the geometric center point in FIG. 18 at 10 mm intervals from the reference femoral resection plane shown in FIG. 16 for all groups in FIG. 21 when moving along the femur from distal to proximal. [Figure 23] 20 for each group in FIG. 21. FIG. [Fig. 24A-C] 24A is an exploded side view of a tibial component with a sleeve according to an example embodiment of the present disclosure, FIG. 24B is another exploded side view of the tibial component of FIG. 24A, and FIG. 24C is a perspective view of an example embodiment of an anatomically shaped tibial component with a sleeve according to the present disclosure. [Figure 25A-C] 1A is a lateral view (left) of a femoral component with a sleeve of the present disclosure and a proximal view (right) of various anatomically shaped femoral sleeves of the present disclosure, and FIG. 1C is a perspective view of various anatomically shaped femoral sleeves of the present disclosure. [Figure 26] FIG. 1 shows a typical femoral and tibial bone defect in revision knee arthroplasty. [Figure 27A-C] A is a diagram showing steps for drilling the distal tibia with a reamer to cortical contact in a tibial preparation technique, B is a diagram showing steps for a tibial broach and trial stem, and C is a diagram showing steps for press-fitting the broach and trial stem in a tibial preparation technique. [Fig. 28A-B] (A) is a top view of a sleeve on the proximal tibia, showing how the sleeve of the present disclosure matches the anatomy of the proximal tibia and creates an optimal environment for stabilization and bone ingrowth, and (B) is a top view of the proximal tibia, showing how the anatomy of the proximal tibia is manipulated to create an optimal environment for sleeve stabilization and bone ingrowth. [Figure 29A-B] FIG. 1A illustrates the press-fit process of the tibial sleeve and stem construct of the present disclosure, and FIG. 1B illustrates a top view of the sleeve on the proximal tibia, showing how the sleeve of the present disclosure matches the anatomy of the proximal tibia and creates an optimal environment for stabilization and bone ingrowth. [Fig. 30A-B] FIG. 1A illustrates a femoral preparation technique step for drilling a distal femur to cortical contact with a reamer; FIG. 1B illustrates a femoral preparation technique step for testing a femoral broach and stem. [Fig. 31A-B] (A) is a side view of the sleeve of the present disclosure, which matches the anatomy of the distal femur to create an optimal environment for stabilization and bone ingrowth, and (B) is an inferior view of the distal femur, showing how the anatomy of the distal femur is manipulated to create an optimal environment for sleeve stabilization and bone ingrowth. [Fig. 32A-B] 32A is a perspective view of the tibial sleeve of the present invention in which the opening for the stem is offset anteriorly and medially from the geometric center of the cancellous bone at the proximal surface of the tibia, and B is an anterior view of the tibial sleeve of FIG. 32A in which the opening for the stem is aligned with the tibial tunnel. [Figure 33A-B] A is a top view of the tibial sleeves of the present invention, which have a greater medial gradient compared to the lateral to match the underlying anatomy, and B is a front view matching the left to right side of the tibial sleeve of Fig. 33A, where the size of the tibial sleeve increases by adding incremental steps, making the up and down size progression intuitive and streamlining the instrumentation. [Figure 34A] FIG. 2 is a front view of the tibial sleeve of the present invention, showing how the tibial sleeve configuration matches the underlying anatomy while preserving bone, maximizing the implant-to-bone contact surface area for long-term ingrowth. [Figure 34B] FIG. 34B is a top perspective view of the tibial sleeve of FIG. 34A. [Fig. 34C-D] 34C is a top view of a tibial sleeve of one embodiment of the present invention, and FIG. 34D is a front view of the tibial sleeve of FIG. 34C. [Fig. 35A-B] 35A is an underside view of the femoral sleeve of the present invention, in which the femoral sleeve configuration matches the underlying anatomy while preserving bone, optimizing the implant, and B is a front view of the femoral sleeve of FIG. [Fig. 36A-B] 36A is a top view of the femoral sleeve of the present invention where the opening in the femoral sleeve for the stem is angled 6 degrees to accommodate the femoral canal, and B is a front view that matches the left to right side of the femoral sleeve in FIG. 36A where the femoral sleeve size increases by adding incremental steps, making the up and down size progression intuitive and streamlining the instrumentation. [Fig. 36C-D] 36C is a top view of a femoral sleeve according to one embodiment of the present invention, and FIG. 36D is a front view of the femoral sleeve of FIG. 36C. [Fig. 37A-B] 37A is a perspective view of the tibial cone of the present invention in which the opening for the stem is offset anteriorly and medially from the geometric center of the cancellous bone at the proximal surface of the tibia. B is an anterior view of the tibial cone of FIG. 37A in which the opening for the stem is aligned with the tibial tunnel. [Fig. 38A-B] A is a top view of the tibial cones of the present invention, which have a greater medial gradient compared to the lateral gradient to match the underlying anatomy, and B is a front view matching the left to right sides of the tibial cones of Fig. 38A, in which the size of the tibial cones increases by adding incremental steps, making the up and down size progression intuitive and streamlining the instrumentation. [Fig. 39A-B] (A) is a front view of the tibial cone of the present invention, in which the configuration of the tibial cone matches the underlying anatomy while preserving bone, maximizing the implant-bone contact surface area for long-term ingrowth. (B) is a top perspective view of the tibial cone of FIG. [Figure 39C-D] 39C is a top view of a tibial cone of one embodiment of the present invention, and FIG. 39D is a front view of the tibial cone of FIG. 39C. [Fig. 40A-B] 40A is an underside view of the femoral cone of the present invention, in which the femoral cone configuration matches the underlying anatomy while preserving bone to optimize the implant, and B is an anterior view of the femoral cone of FIG. [Fig. 41A-B] 41A is a top view of the femoral cone of the present invention where the opening in the femoral cone for the stem is angled 6 degrees to accommodate the femoral canal, and B is a front view that matches the left to right side of the femoral cone in FIG. 41A where the size of the femoral cone increases by adding incremental steps, making the up and down size progression intuitive and streamlining the instrumentation. [Fig. 41C-D] 41C is a top view of a femoral cone of one embodiment of the present invention, and FIG. 41D is a front view of the femoral cone of FIG. 41C. [Fig. 41E-F] 41E is a top view of another embodiment of a femoral cone of the present invention with a portion of the anterior wall removed, and FIG. 41F is a front view of the femoral cone of FIG. 41E. [Figure 41G]FIG. 13 is a top view of a femoral cone according to yet another embodiment of the present invention, in which the anterior wall of the femoral cone is thinner to accommodate the bowing of the femur, thereby allowing for more sagittal freedom when seating the femoral stem. [Diagram 42] FIG. 13 is a top anterior perspective view of a non-limiting example tibial cone with a portion of the wall of the tibial cone removed to accommodate a larger sized stem or to position the stem at a range of positions and angulations. [Diagram 43] FIG. 43 is an upper front perspective view corresponding to the tibial cone of FIG. 42 , in which the size of the tibial cone increases by adding incremental steps, which makes the up and down size progression intuitive and streamlines the instrument. [Diagram 44] FIG. 13 is a top anterior perspective view of another non-limiting example tibial cone having a stepped outer wall and a notch for a tibial component fin. [Diagram 45] FIG. 13 is a top anterior perspective view of yet another non-limiting example tibial cone having a smooth outer wall and a notch for a tibial component fin. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] In the following description, with reference to the drawings, like parts are designated with like reference numerals in each figure.

[0050] Before describing the present invention in detail, it should be understood that the present invention is not limited to the specific embodiments described herein. It should also be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the present invention, the scope of which is limited only by the claims. As used herein, the singular forms "a", "an" and "the" include plural embodiments unless the context clearly dictates otherwise.

[0051] It will be apparent to those skilled in the art that in addition to those described herein, many other modifications are possible without departing from the spirit of the invention. In interpreting this disclosure, all terms should be interpreted in the broadest possible manner consistent with the context. The various variations of the terms "comprising", "including", and "having" refer to elements, components, or steps in a non-exclusive manner, such that the elements, components, or steps referred to by these terms can be combined with other elements, components, or steps not expressly mentioned by these terms. An embodiment described as "comprising", "including", or "having" a particular element also has the meaning of "consisting essentially of" or "consisting of" that element, unless the context clearly dictates otherwise. It will be apparent that each aspect of the apparatus disclosed herein is also applicable to a method, and vice versa, unless the context clearly dictates otherwise.

[0052] In one aspect, the disclosure provides a prosthetic system for providing motion between a first bone and a second bone of a joint. The system includes a support structure (e.g., a sleeve or cone, etc.) having a first end face, a second end face, an outer surface extending from the first end face to the second end face, and an inner surface defining a passageway extending from the first end face to the second end face, the outer surface of the sleeve being configured to be received within a cavity of the first bone such that the first end face is flush with or recessed from a surface of the first bone. The first end face lies in an axial plane defined by the first end face and an outermost edge of the first end face, and a longitudinal axis of the passageway of the support structure (e.g., a sleeve or cone, etc.) is offset from a geometric center point of the axial plane. In one embodiment, the first bone is the tibia and the joint is the knee. In another embodiment, the first bone is the femur and the joint is the knee.

[0053] In another aspect, the present disclosure provides a kit for a prosthetic system for providing motion between a first bone and a second bone of a joint, the kit can include a first support structure (e.g., a sleeve or cone, etc.) of the present disclosure and one or more additional support structures (e.g., a sleeve or cone, etc.) of different sizes of the present disclosure.

[0054] In another aspect, the disclosure provides a method for manufacturing a prosthetic support structure (e.g., a sleeve or cone, etc.) for implantation into a cavity in an end of a bone, the method including forming a prosthetic support structure (e.g., a sleeve or cone, etc.) having an outer surface sized to fit into the cavity in the end of the bone and an inner surface defining a passage in the prosthetic support structure (e.g., a sleeve or cone, etc.), the passage being sized to receive a stem of a prosthetic implant, the passage extending from a first end surface to a second end surface of the support structure (e.g., a sleeve or cone, etc.). The first end surface of the support structure (e.g., a sleeve or cone, etc.) lies in an axial plane defined by the first end surface and an outermost edge of the first end surface, the passage having a longitudinal axis. The intersection point between the axial plane and the longitudinal axis of the passage is determined by: (i) acquiring an image of a reference bone; (ii) orienting, on the image, a first reference axial plane located at a first distance from an end surface of the reference bone; (iii) orienting, on the image, a second reference axial plane located at a second distance from the end surface of the reference bone that is different from the first distance; and (iv) determining a first intersection point determined by a first intersection portion between the inertial axis of the reference bone and the first reference axial plane and a second intersection portion between the inertial axis of the reference bone and the second reference axial plane. (v) orienting on the image a reference resection plane having a boundary defined by an axial image of the reference bone; and (vi) orienting on the image a reference intersection point between the reference resection plane and the intramedullary axis, the reference spatial relationship between the reference intersection point and the boundary of the reference resection plane corresponding to a spatial relationship between the intersection point on the axial plane and an outermost edge of a first end surface of the support structure (e.g., a sleeve or cone). In one embodiment, the bone is a tibia. In another embodiment, the bone is a femur.

[0055] <Example> The following examples are intended to illustrate and further illustrate certain embodiments and aspects of the present invention and are not to be construed as limiting the scope of the invention.

[0056] <Project Resources> A unique database of 50 consecutive high-resolution thin-slice two-dimensional and three-dimensional computed tomography (CT) scans with a custom-designed bone stock protocol was provided for the study. This custom-designed protocol was specifically developed to understand the patient anatomy in detail at Mayo Clinic (Rochester, Minnesota, USA). In addition, 3D modeling was performed for each of these patients. This unique resource was then used to develop novel methods for understanding and 3D modeling the anatomy of the proximal tibia and distal femur. The Materialise® 3-matic Medical software interface and image segmentation system were used to perform the CT image measurements and calculations.

[0057] <Methods, Results and Implications> A. Anatomy of the Proximal Tibia 1. Definition of the Intramedullary Axis (IM Axis) Referring to FIG. 5, points were marked on the CT image of the tibia 510 at 50 mm (5 cm) and 100 mm (10 cm) from the tibial lateral cortical plateau 512. A first plane 514 and a second plane 516 were created perpendicular to the tibia at the 50 mm and 100 mm points along the axial plane. The cancellous image containing the planes was cropped while preserving the original cancellous bone. The upper and lower cancellous bone parts were hidden together with the just created planes. Based on the mesh on the upper and lower surfaces, an axis of inertia 518 was created. A first intersection point 522 of the axis of inertia with the 50 mm plane and a second intersection point 524 of the axis of inertia with the 100 mm plane were drawn. An intramedullary axis 530 was created by connecting these two points 522, 524.

[0058] 2. Making cuts for total knee arthroplasty (TKA) Referring to FIG. 6, a reference tibial resection plane 610 was drawn on each CT tibia scan, which corresponds to a standard tibial resection for total knee arthroplasty. The origin of the reference tibial resection plane 610 was created 10 mm below the lateral tibial plateau 512, above the tibial tubercle and immediately left of center. The reference tibial resection plane 610 is positioned perpendicular to the intramedullary axis (IM axis) 530. The plane 610 is rotated in the XY / axial / lateral plane so that it is aligned with the widest point extending from the medial plateau to the lateral plateau. The plane 610 is rotated 3 degrees toward the medial side of the tibia 510, then 3 degrees toward the posterior side of the tibia 510.

[0059] 3. Measurement of deviation from IM axis 7A and 7B, intramedullary points 710a-710l are defined as the intersections of each axial slice with the intramedullary axis 530. These are useful as reference points for making various measurements. The geometric center points 720a-720l are the centroids of each axial slice. The centroid of a plane figure is the arithmetic mean location of all points within that plane figure. The centroid is the point where a cutout of the shape would be perfectly balanced on the tip of the pin.

[0060] The distance between these two points 710a, 720a represents the offset between the shaft and the proximal tibia.

[0061] 4.Angle deviation measurement 8, the angular deviation is a measurement of the angle A between the intramedullary axis point 710a, the geometric center point 720a, and the x-axis (eg, in FIG. 8, angle A is 77.83°).

[0062] 5.Full width measurement 9, the widths in each axial slice are measured in both directions through the geometric center point 720a of that slice. The anterior-posterior width is the distance from the PCL intersection to the center of the tibial tubercle. The mediolateral width is the width perpendicular to the AP width that contains the maximum width of that slice.

[0063] 6. Radial measurement Radial measurements are based on the intramedullary center point 710a of the axial slice. The distance from the intramedullary center point 710a to the edge of the slice is measured every 5 degrees clockwise on the anterior, lateral, posterior, and medial sides. The above data was averaged for each group to create a general overview of the cancellous bone of each axial slice.

[0064] 7. Results of the proximal tibia The medial and lateral widths of the proximal tibia were classified into groups of 4 mm each. The tibias were grouped according to width: 54–58 mm, 58–62 mm, 62–66 mm, 66–70 mm, 70–74 mm, 74–78 mm, and 78–82 mm (see Figure 11).

[0065] Moving from proximal to distal along the tibia, the total distance between each intramedullary point 710a-710l and each geometric center point 720a-720l was determined for all groups (see FIG. 12A) and also as an overall average (see FIG. 12B).

[0066] Graph showing the average deviation of the geometric center points 720a-720l from the intramedullary axis 530 of the tibia for all groups (see FIG. 13A) and the overall average (FIG. 13B).

[0067] The angular deviation is a measurement result for all groups of angles between each intramedullary point 710a-710l and each geometric center point 720a-720l and the x-axis (see FIG. 14A) and a measurement result for the overall average (see FIG. 14B).

[0068] - The radial measurements for each group show the contour of the tibia in the scan (see Figure 15).

[0069] B. Distal Femur Anatomy 1. Definition of the Intramedullary Axis (IM Axis) Referring to Fig. 16, on a CT image of a femur 1610, a first plane was created perpendicular to the femur 1610 at 75 mm above the inner side of the femur, and a second plane was created perpendicular to the femur 1610 at 175 mm above the inner side of the femur 1610. An axis of inertia was created, and a first intersection point 1622 between the axis of inertia and the 75 mm plane and a second intersection point 1624 between the axis of inertia and the 175 mm plane were entered. An intramedullary axis 1630 was created by connecting the above two points 1622, 1624. The intramedullary axis 1630 represents the center of the intramedullary canal in the distal femur.

[0070] 2.Full width measurement With reference to FIG. 17, the distance between the medial and lateral epicondyles in the cancellous bone was taken as the overall width (eg, 68.35 mm in FIG. 17).

[0071] 3. Measurement of deviation from the intramedullary (IM) axis Referring to FIG. 18, to quantify the offset required for the knee sleeve, the distance between the intramedullary axis point 1650 (the intersection of the tomography and the IM axis) and the geometric center point 1660 was measured on the XY plane.

[0072] FIG. 19 shows a visualization of the IM axis 1630 and the geometric centerline 1640.

[0073] 4. Radial measurement Referring to FIG. 20A, to find the average shape of each group, the distance extending from the IM axis point 1650 to the edge of the cancellous bone was recorded every 5 degrees in each slice.

[0074] 5.Creating the femoral cutting surface 20B, the femoral cutting surface 2010 was selected as the reference surface for all measurements. It is located 10 mm above the lowest point on the medial side of the femur 1610. The surface 2010 slopes downwards by 5 degrees anteriorly and medially relative to the IM axis 1630.

[0075] 6. Distal femur results The medial and lateral widths of the reference femoral resection surface 2010 of the distal femur were classified into multiple groups of 5 mm each. The femurs were grouped according to width into a 65-70 mm width group, a 71-75 mm width group, a 75-80 mm width group, a 80-85 mm width group, and a 85 mm width group (see FIG. 21).

[0076] The total distance between the IM axis point and the geometric center point while moving the femur from distal to proximal was determined for all groups. (See Figure 22).

[0077] The radial measurements for each group show the femoral contours (see Figure 23).

[0078] C. Results The total deviation from the intramedullary axis point to the geometric center point in the scans moving along the tibia (proximal to distal direction) was significant, confirming why it is difficult for surgeons to use symmetric sleeves and straight stems in tibial revision knee arthroplasties. Furthermore, there was a clear trend for the total distance between these two points to increase with increasing tibia size. This means that we need to look at the individual amount of offset that must be designed into the tibial prosthesis based on the individual size of the proximal tibia width (see Figures 12A and 12B).

[0079] It can be seen that the deviation from the IM axis to the geometric center point when moving distally in the tibia is in the anterior-medial direction (Figures 13A and 13B). This method revealed that deviations occur in multiple planes and that the curvature of the cancellous bone does not follow a linear trend line.

[0080] Angular deviation is a measurement of the angle between the intramedullary axis point, the geometric center point, and the x-axis (see FIGS. 14A and 14B). The shift in location between the geometric center point and the intramedullary axis point gives a specific angular change in the above relationships as one moves distally in the tibia.

[0081] Radial measurements quantify the difference between the medial and lateral sides of the proximal tibia. Figure 15 shows an example of radial measurements taken every 30 degrees on the most proximal tibia plane. This provides important information for the creation of a sleeve of appropriate size and shape.

[0082] For the femur, the total deviation from the intramedullary axis to the geometric center along the femur (distal to proximal) was also significant, confirming why it is difficult for surgeons to use symmetric sleeves and straight stems in femoral revision knee arthroplasties. The maximum total distance is approximately 4.5 mm. This maximum total distance is at the very distal end of the femur, which is where the greatest variability occurs.

[0083] This is an important point to note as it suggests that the cancellous bone is not very straight. The distance reaches a local minimum at approximately 50 mm from the cutting surface, increases continuously, then decreases to zero. This method helps determine the anatomical offset of the stem relative to the distal femur. Furthermore, radial measurements showed that there was a larger deviation in the medial-lateral direction than in the anterior-posterior direction, which reflects the designed sleeve.

[0084] D. Component Design Implications The method confirmed that the proximal tibia and distal femur regions are not naturally symmetrical, highlighting the difficulty of forcing circular and symmetrical instruments into these regions. Additionally, the method demonstrated clear differences in the architecture of the proximal medial and proximal lateral tibia, as well as the distal medial and distal lateral femur. To minimize the medial overhang of the tibial tray, many surgeons are forced to significantly downsize the tibial component, which impacts joint kinematics. Additionally, the system must size the femoral component similarly to the tibial component. The need to downsize the tibial component forces the surgeon to use a suboptimal sized femoral component. The method facilitates the design of an anatomically shaped sleeve that accommodates the bone defects in the regions.

[0085] The above method helps clearly define the offset between the centers of the tibia and femur at the joint line and the center of the distal tube in which the stem sits. Currently available systems do not adequately account for this. The above method allows for the design of the implant size and angular orientation to accommodate this offset.

[0086] The method described above clearly shows that different sleeves are needed for the medial and lateral sides. Furthermore, the radial measurements provide important findings that show exactly how the sleeve should be enlarged in the medial-lateral and anterior-posterior directions, as the sleeve increases in size in both directions.

[0087] E. Application of the above method to revision knee arthroplasty and creation of an anatomical system According to the above method, a complete set of anatomically shaped sleeves or cones for tibial and femoral reconstruction in revision knee arthroplasty has been developed. Furthermore, the specific orientation of the stem relative to the sleeve or cone is adjusted scientifically and based on actual anatomical grounds. Seven tibial sleeves 2420a-2420g (see FIG. 33A) and six femoral sleeves 2520a-2520f (see FIG. 25B) have been created based on the distribution of anatomical measurements that maximize the contact with the underlying bone. A similar size distribution has been created for the cones. A complete set of broaches, sleeves, adapters, cones, and stems has been created. The above sizes, shapes, and positions of the femoral and tibial sleeves facilitate a reconstructive surgery that maximizes bone preservation and optimizes the contact with the host bone. Similarly, the above sizes, shapes, and positions of the femoral and tibial cones facilitate a reconstructive surgery that maximizes bone preservation and optimizes the contact with the host bone. The offset of the stem relative to the sleeve or cone is achieved by the methods described above, thereby optimizing the fit and minimizing the risk of iatrogenic fracture.

[0088] <Non-limiting example sleeve> 32A and 32B, a tibial component 3210 is shown, which includes a sleeve 2420d, a stem 2430, and an adaptor 2440. The offset of the stem 2430 facilitates centering the stem 2430 along the tibial tunnel. Additionally, the sleeve has a greater medial taper compared to the lateral side to match the underlying anatomy. Additionally, the asymmetrical shape of the tibial sleeve maximizes contact with the underlying bone (see FIGS. 33A, 33B, 34A, and 34B).

[0089] In Figures 32A and 32B, the opening in the sleeve 2420d for the stem 2430 is offset anteriorly and medially relative to the geometric center point of the cancellous bone on the proximal surface of the tibia.

[0090] In FIG. 33A, sleeves 2420a-2420g have a greater medial gradation compared to the lateral side to match the underlying anatomy.

[0091] In FIG. 33B, the tibial sleeves 2420a-2420g increase in size by adding incremental steps, which makes the up and down size progression intuitive and allows for streamlining of the instrument.

[0092] In Figures 34A and 34B, the configuration of the tibial sleeve 2420d matches the underlying anatomy while preserving bone, maximizing the implant-to-bone contact surface area for long-term ingrowth.

[0093] 34C and 34D show a tibial sleeve 2420d according to one embodiment of the present invention. The sleeve 2420d has a first end surface 3420, a second end surface 3430, an outer surface 3440 extending from the first end surface 3420 to the second end surface 3430, and an inner surface 3450 defining a passageway 3460 extending from the first end surface 3420 to the second end surface 3430, the outer surface 3440 of the sleeve 2420d being configured to be received within a tibial cavity such that the first end surface 3420 is flush with or recessed from the resected tibial surface. The first end surface 3420 includes slots 3480a and 3480b, each of which is sized to receive a stabilizing arm of a stem. The first end surface 3420 lies in an axial plane defined by the first end surface 3420 and an outermost edge 3470 (in this embodiment, a circumferential edge) of the first end surface 3420. The longitudinal axis LA of the passageway 3460 of the sleeve 2420d is offset from a geometric center point of the axial plane. The longitudinal axis LA of the passageway 3460 of the sleeve 2420d can correspond to the intramedullary axis as identified above with reference to FIG. 5.

[0094] The outer surface of the tibial sleeve 2420d can have a variety of surfaces including smooth, rough, grit blasted, and can have porous ingrowth material for bone ingrowth. For example, an open cell tantalum structure has been developed for potential applications in reconstructive surgery and other surgical fields. This material has high porosity and interconnected pores, with very regular pore shapes and sizes. This material can be made into complex shapes as a surface coating. It has been found that "trabecular metal" allows for physiological bone growth and healing. The outer surface of the tibial sleeve 2420d can also be modified by sandblasting or bead blasting or by roughening in some other manner. The surface can also be modified by shaping, for example, blades, sharp structures, machined lines, or geometric features on the outer surface.

[0095] The tibial sleeve 2420d can be used in a prosthetic system with a tibial implant having a body and an attached stem extending away from the body, with the stem 2430 positioned within the passage 3460 of the sleeve 2420d as in FIG. 32B. The tibial sleeve 2420d can be used in a prosthetic system with a tibial tray as shown in FIG. 2 and a tibial bearing (shown as 130 in FIG. 1) in contact with the tibial tray, with the tibial bearing having a bearing surface for coupling with the articular surface of the femoral component. The femoral sleeve can be used in a prosthetic system with a femoral component having medial and lateral condyles with curved articular surfaces as shown in FIG. 1. The femoral sleeve 2520d can be used in a prosthetic system with a femoral implant having a body and an attached stem 2530 extending away from the body, with the stem 2530 positioned within the passage 3660 of the femoral sleeve 2520d as in FIG. 35B.

[0096] In currently commercial revision knee systems, this stem offset is not adequately considered in the design, resulting in two significant clinical problems: (1) If the stem is placed along the center of the canal, symmetric sleeves currently on the market cannot be used to optimally contact the rest of the bone, increasing the stress on the construct and the opportunity for failure; and (2) if the surgeon attempts to asymmetrically place a symmetric sleeve on the proximal tibia to engage the natural bone structure, they are forced to place the stem eccentrically in the canal, which causes implant misalignment.

[0097] Both of these commonly encountered problems are eliminated by the construction of the present invention, which has the advantageous step of first centering the stem within the canal and then growing the sleeve or cone where the bone is located.

[0098] The present invention provides a system that maximizes bone preservation with sleeves and cones that logically increase in size with incremental steps. The femur 3500, which is similar to the tibia, also shows the design philosophy with an anatomically shaped sleeve that optimizes contact with the underlying bone. Figures 35A and 35B show a femoral component 3510 that includes a sleeve 2520d, a stem 2530, and an adaptor 2540. The configuration of the femoral sleeve 2520d matches the underlying anatomy, allowing for bone preservation and implant optimization. Figure 36A shows a top view of femoral sleeves 2520a-2520f of the present invention, where the opening of the femoral sleeve for the stem is angled at 6 degrees to correspond to the femoral canal. 36B is a front view of the femoral sleeves 2520a-2520f, which increase in size by adding incremental steps, making the up and down size progression intuitive and streamlining the instrument. The femoral sleeves 2520a-2520f have a 6 degree angle that matches the femoral tunnel, improving size options.

[0099] The outer surface of any of the femoral sleeves 2520a-2520f can have a variety of surfaces, including smooth, rough, grit blasted, and can have porous ingrowth material for bone ingrowth. For example, open cell tantalum structures have been developed for potential applications in reconstructive surgery and other surgical fields. This material has high porosity and interconnected pores, with very regular pore shapes and sizes. This material can be made into complex shapes as a surface coating. It has been found that "trabecular metal" allows for physiological bone growth and healing. The outer surface of the femoral sleeves 2520a-2520f can also be modified by sandblasting or bead blasting or by roughening in some other manner. The surface can also be modified by shaping, for example, blades, sharp structures, machined lines, or geometric features on the outer surface.

[0100] 36C and 36D show a femoral sleeve 2520d according to an embodiment of the present invention. The sleeve 2520d has a first end surface 3620, a second end surface 3630, an outer surface 3640 extending from the first end surface 3620 to the second end surface 3630, and an inner surface 3650 defining a passageway 3660 extending from the first end surface 3620 to the second end surface 3630, the outer surface 3640 of the sleeve 2520d being configured to be placed within a cavity of the femur such that the first end surface 3620 is flush with or recessed from the resected surface of the femur. The first end surface 3620 lies in an axial plane defined by the first end surface 3620 and an outermost edge 3670 (in this embodiment, a circumferential edge) of the first end surface 3620. The longitudinal axis LA2 of the passageway 3660 of the sleeve 2520d is offset from the geometric center point of the axial plane. The longitudinal axis LA2 of the passageway 3660 of the sleeve 2520d can correspond to the intramedullary axis as identified above with reference to FIG.

[0101] In the femoral sleeve 2520d, the longitudinal axis LA2 of the passageway 3660 of the sleeve 2520d forms an oblique angle with a normal to an axial plane defined by the first end face 3620 and the outermost edge 3670 of the first end face 3620. The oblique angle can be greater than 0 degrees and less than 10 degrees. The oblique angle can be greater than 3 degrees and less than 9 degrees. The oblique angle can be 5 or 6 or 7 degrees.

[0102] The femoral sleeve 2520d can be used in a prosthetic system having a femoral component with medial and lateral condyles having curved articular surfaces as shown in Figure 1. The femoral sleeve 2520d can be used in a prosthetic system having a femoral implant having a body and an attached stem 2530 extending away from the body, the stem 2530 being disposed within the passageway 3660 of the sleeve 2520d as shown in Figure 35B. The femoral sleeve 2520d can be used in a prosthetic system having a tibial tray as shown in Figure 2 and a tibial bearing (shown as 130 in Figure 1) in contact with the tibial tray, the tibial bearing having a bearing surface for interfacing with the articular surface of the femoral component.

[0103] The increased size range greatly expands the potential use of the sleeve in revision knee arthroplasty. Current sleeves are limited in size and have a large gap between sizes that are too small and force in implants that do not maximize contact, and sizes that require additional bone removal to fit the implant. The smaller size sleeves of the present invention provide an increased market for the use of the sleeve, making it an attractive, premium-priced, high-value product for manufacturers.

[0104] Additionally, the above system and implant streamlines the flow of surgery. For the tibia, the distal size is established with a cylindrical reamer, and then a sleeve broach is used to ensure maximum support and minimize bone removal. The same is true for the femur after engagement with the proximal femoral shaft. The system of the present invention allows any size sleeve to be used with any size stem. This greatly facilitates expanding the range of sleeve use in revision cases, expanding market opportunities. For example, the use of smaller sleeves for any size patient provides a better option compared to using bone grafts, cement, or additional bone removal to fit current non-anatomical shaped and sized sleeves.

[0105] The sleeve may be made from metal alloys such as titanium alloys (e.g. titanium-6-aluminum-4-vanadium), cobalt-chromium alloys, stainless steel alloys and tantalum alloys, non-resorbable ceramics such as aluminum oxide and zirconia, non-resorbable polymeric materials such as polyethylene, or composite materials such as carbon fiber reinforced polymers (e.g. polysulfone). Preferably, the sleeve is made from a tantalum-based porous material or other metals coated with a tantalum-based porous metal or other porous coating.

[0106] <Non-limiting examples of cones> The outer shape and diameter of the cone can be similar to the outer shape and diameter of the sleeve. The inner diameter of the cone can be wider than the inner diameter of the sleeve. In some configurations, the proximal and distal openings of the cone are wider than the proximal and distal openings of the sleeve. This allows the stem to pass through the cone at a larger range of positions and angles than the sleeve.

[0107] The cone can be made using the same method as the sleeve, then removing material from the inside to create a larger inner diameter. The stem anatomy and offset can be similar in both cases and based on the methods above.

[0108] 37A and 37B, a tibial component 3710 is shown, which includes a cone 3720, a stem 3730, and an adaptor 3740. It can be seen that the offset of the stem 3730 helps to center the stem 3730 along the tibial tunnel. Additionally, the cone has a greater medial taper compared to the lateral side to match the underlying anatomy. Additionally, the asymmetrical shape of the tibial cone can be seen to maximize contact with the underlying bone (see FIGS. 33A, 33B, 34A, 34B).

[0109] In Figures 37A and 37B, the opening in the cone 3720 for the stem 2730 is offset anteriorly and medially relative to the geometric center point of the cancellous bone on the proximal surface of the tibia.

[0110] In FIG. 38A, cones 3820a-3820g are significantly tapered medially compared to laterally to match the underlying anatomical structure.

[0111] In FIG. 38B, the tibial cones 3820a-3820g increase in size by adding incremental steps, which makes the up and down size progression intuitive and allows for streamlining of the instrument.

[0112] In Figures 39A and 39B, the configuration of the tibial cone 3820f matches the underlying anatomy while preserving bone, maximizing the implant-to-bone contact surface area for long-term ingrowth.

[0113] 39C and 39D show a tibial cone 3820d of one embodiment of the present invention. The cone 3820d has a first end surface 3920, a second end surface 3930, a stepped outer surface 3940 extending from the first end surface 3920 to the second end surface 3930, and an inner surface 3950 defining a passageway 3960 extending from the first end surface 3920 to the second end surface 3930, the outer surface 3940 of the cone 3820d being configured to be placed into the tibial cavity such that the first end surface 3920 is flush with or recessed from the resected tibial surface. A stem for use with the cone may include stabilizing arms 3980a and 3980b. The first end surface 3920 lies in an axial plane defined by the first end surface 3920 and an outermost edge 3970 (in this embodiment, a circumferential edge) of the first end surface 3920. The longitudinal axis LA of the passageway 3960 of the cone 3820d is offset from a geometric center point of the axial plane. The longitudinal axis LA of the passageway 3960 of the cone 3820d may correspond to the intramedullary axis as identified above with reference to FIG. 5.

[0114] The tibial cone 3820d can be used in a prosthetic system with a tibial implant having a body and a stem extending away from the body, the stem being disposed within the passageway 3960 of the cone 3820d as in FIG. 37B. The tibial cone 3820d can be used in a prosthetic system with a tibial tray as shown in FIG. 2 and a tibial bearing (shown as 130 in FIG. 1) in contact with the tibial tray, the tibial bearing having a bearing surface for interfacing with the articular surface of a femoral component. The cone can be used in a prosthetic system with a femoral component with medial and lateral condyles having curved articular surfaces as shown in FIG. 1.

[0115] The outer surface of any of the tibial cones 3820a-3820g can have a variety of surfaces including smooth, rough, grit blasted, and can have porous ingrowth material for bone ingrowth. For example, open cell tantalum structures have been developed for potential applications in reconstructive surgery and other surgical fields. This material has high porosity and interconnected pores with very regular pore shapes and sizes. This material can be made into complex shapes as a surface coating. It has been found that "trabecular metal" allows for physiological bone growth and healing. The outer surface of the tibial cones 3820a-3820g can also be modified by sandblasting or bead blasting or by roughening in some manner. The surface can also be modified by shaping, for example, blades, sharp structures, machined lines, or geometric features on the outer surface.

[0116] Both of the above commonly encountered problems with stem offset failure as mentioned above with the sleeve are eliminated by the inventive arrangement which has the significant step of first centering the stem within the canal and then growing the cone where the bone is located.

[0117] The present invention provides a system that maximizes bone preservation with a sleeve or cone that logically increases in size with incremental steps. The design philosophy can be seen on the femur 4000, which is similar to the tibia, with an anatomically shaped cone that optimizes contact with the underlying bone. In Figs. 40A and 40B, a femoral component 4010 is shown, which includes a cone 4020, a stem 4030, and an adaptor 4040. The configuration of the femoral cone 4020 matches the underlying anatomy, allowing for bone preservation and implant optimization. Fig. 41A shows a top view of femoral cones 4020a-f of the present invention, where the opening of the femoral cone for the stem is angled at 6 degrees to correspond to the femoral canal. 41B is a front view of the femoral cones 4020a-4020f, which increase in size by adding incremental steps, making the up and down size progression intuitive and streamlining the instrument. The femoral cones 4020a-4020f have a 6 degree angle that matches the femoral tunnel, improving size options.

[0118] 41C and 41D show a femoral cone 4020d according to one embodiment of the present invention. The cone 4020d has a first end surface 4120, a second end surface 4130, a stepped outer surface 4140 extending from the first end surface 4120 to the second end surface 4130, and an inner surface 4150 defining a passageway 4160 extending from the first end surface 4120 to the second end surface 4130. The outer surface 4140 of the cone 4020d is configured to be received within a cavity of a femur such that the first end surface 4120 is flush with or recessed from the resected surface of the femur. The first end surface 4120 lies in an axial plane defined by the first end surface 4120 and an outermost edge 4170 of the first end surface 4120. The longitudinal axis LA2 of the passageway 4160 of the cone 4020d is offset from the geometric center point of the axial plane. The longitudinal axis LA2 of the passageway 4160 of the cone 4020d can correspond to the intramedullary axis as identified above with reference to FIG.

[0119] In the femoral cone 4020d, the longitudinal axis LA2 of the passageway 4160 of the cone 4020d forms an oblique angle with a normal to an axial plane defined by the first end face 4120 and the outermost edge 4170 (in this embodiment, the circumferential edge) of the first end face 4120. The oblique angle can be greater than 0 degrees and less than 10 degrees. The oblique angle can be greater than 3 degrees and less than 9 degrees. The oblique angle can be 5 or 6 or 7 degrees.

[0120] The outer surface of any of the femoral cones 4020a-f can have a variety of surfaces, including smooth, rough, grit blasted, and can have porous ingrowth material for bone ingrowth. For example, open cell tantalum structures have been developed for potential applications in reconstructive surgery and other surgical fields. This material has high porosity and interconnected pores, with very regular pore shapes and sizes. This material can be made into complex shapes as a surface coating. It has been found that "trabecular metal" allows for physiological bone growth and healing. The outer surface of the femoral cones 4020a-f can also be modified by sandblasting or bead blasting or by roughening in some other manner. The surface can also be modified by shaping, for example, blades, sharp structures, machined lines, or geometric features on the outer surface.

[0121] The femoral cone 4020d can be used in a prosthetic system having a femoral component with medial and lateral condyles having curved articular surfaces as shown in Figure 1. The femoral cone 4020d can be used in a prosthetic system having a femoral implant having a body and a stem extending away from the body, the stem being disposed within the passageway 4160 of the cone 4020d as shown in Figure 40B. The femoral cone 4020d can be used in a prosthetic system having a tibial tray as shown in Figure 2 and a tibial bearing (shown as 130 in Figure 1) in contact with the tibial tray, the tibial bearing having a bearing surface for interfacing with the articular surface of the femoral component.

[0122] 41E and 41F show another embodiment of a femoral cone 4020e with a portion of the anterior wall removed to form a notch in the cone 4020e. The cone 4020e has a first end 4180, a second end 4181, a stepped outer surface 4183 extending from the first end 4180 to the second end 4181, and an inner surface 4182 defining a passageway 4184 extending from the first end 4180 to the second end 4181, the outer surface 4183 of the cone 4020e being configured to be placed into a cavity in the femur such that the first end 4180 is flush with or recessed from the resected surface of the femur. The anterior wall of the cone 4020e has a notch 4188. Removing a portion of the anterior wall accommodates the bowing of the femur, thereby allowing for increased sagittal freedom when seating the femoral stem. The first end surface 4180 lies in an axial plane defined by the first end surface 4180 and the outermost edge 4186 of the first end surface 4180. The longitudinal axis LA2 of the passageway 4184 of the cone 4020e is offset from the geometric center point of the axial plane. The longitudinal axis LA2 of the passageway 4184 of the cone 4020d may correspond to the intramedullary axis as identified above with reference to FIG. 16.

[0123] In the femoral cone 4020e, the longitudinal axis LA2 of the passageway 4184 of the cone 4020e forms an oblique angle between the first end face 4180 and a normal to an axial plane defined by the outermost edge 4186 of the first end face 4180. The oblique angle can be greater than 0 degrees and less than 10 degrees. The oblique angle can be greater than 3 degrees and less than 9 degrees. The oblique angle can be 5 or 6 or 7 degrees.

[0124] The femoral cone 4020e can be used in a prosthetic system having a femoral component with medial and lateral condyles having curved articular surfaces as shown in Figure 1. The femoral cone 4020e can be used in a prosthetic system having a femoral implant having a body and a stem extending away from the body, the stem being disposed within the passageway 4184 of the cone 4020e as shown in Figure 40B. The femoral cone 4020e can be used in a prosthetic system having a tibial tray as shown in Figure 2 and a tibial bearing (shown as 130 in Figure 1) in contact with the tibial tray, the tibial bearing having a bearing surface for interfacing with the articular surface of the femoral component.

[0125] 41G is a top view of a femoral cone 4020g according to yet another embodiment of the present invention, in which the anterior wall of the femoral cone is thinned relative to the lateral and medial walls. The cone 4020g has a first end surface 4190, a second end surface (similar to the second end surface 4181 in FIGS. 41E and 41F), an outer surface (similar to the outer surface 4183 in FIGS. 41E and 41F) extending from the first end surface 4190 to the second end surface, and an inner surface 4192 defining a passageway 4194 extending from the first end surface 4190 to the second end surface, the outer surface of the cone 4020g being configured to be placed within the femoral cavity such that the first end surface 4190 is flush with or recessed from the resected surface of the femur. The anterior wall of the cone 4020g has a thin wall portion 4198. The thinning of a portion of the anterior wall accommodates the bowing of the femur, thereby allowing for increased sagittal freedom when seating the femoral stem. The first end surface 4190 lies in an axial plane defined by the first end surface 4190 and the outermost edge 4196 of the first end surface 4190. The longitudinal axis LA2 of the passageway 4194 of the cone 4020g is offset from the geometric center point of the axial plane. The longitudinal axis LA2 of the passageway 4194 of the cone 4020g may correspond to the intramedullary axis as identified above with reference to FIG. 16.

[0126] In the femoral cone 4020g, the longitudinal axis LA2 of the passageway 4194 of the cone 4020g forms an oblique angle between the first end face 4190 and a normal to an axial plane defined by the outermost edge 4196 of the first end face 4190. The oblique angle can be greater than 0 degrees and less than 10 degrees. The oblique angle can be greater than 3 degrees and less than 9 degrees. The oblique angle can be 5 or 6 or 7 degrees.

[0127] The femoral cone 4020g can be used in a prosthetic system having a femoral component with medial and lateral condyles having curved articular surfaces as shown in Figure 1. The femoral cone 4020g can be used in a prosthetic system having a femoral implant having a body and a stem extending away from the body, the stem being disposed within the passageway 4194 of the cone 4020g as shown in Figure 40B. The femoral cone 4020g can be used in a prosthetic system having a tibial tray as shown in Figure 2 and a tibial bearing (shown as 130 in Figure 1) in contact with the tibial tray, the tibial bearing having a bearing surface for interfacing with the articular surface of the femoral component.

[0128] For some sizes of the cones of the present invention, such as smaller sizes, distal portions of the anterior and posterior walls may be removed to accommodate larger stems and to allow the stem to be positioned at a range of positions and angles. This is shown in FIG. 42 where a notch 4210 is formed in the tibial cone 4200 by removing a portion of the wall. Rather than being in a fixed position as with the sleeve, the wider proximal and distal openings of the cone allow the stem to be selectively oriented or angled relative to the cone without hitting the inner edge of the cone, and the notch 4210 provides relief for the lower portion of the stem as it is oriented or angled relative to the longitudinal axis of the cone to prevent it from hitting or binding against the narrower portion of the cone. 42, the tibial cone 4200 has a first end surface 4220, a second end surface 4230, a stepped outer surface 4240 extending from the first end surface 4220 to the second end surface 4230, and an inner surface defining a passageway extending from the first end surface 4220 to the second end surface 4230, the outer surface 4240 of the cone 4200 being configured to be placed within the femoral cavity such that the first end surface 4220 is flush with or recessed from the resected tibia surface. The first end surface 4220 lies in an axial plane defined by the first end surface 4220 and an outermost edge 4270 (in this embodiment, a circumferential edge) of the first end surface 4220.

[0129] The tibial cone 4200 can be used in a prosthetic system that includes a tibial implant having a body and a stem, the stem being positioned within the passageway of the cone 4200 as in Figure 37B. The tibial cone 4200 can be used in a prosthetic system that includes a tibial tray as shown in Figure 2 and a tibial bearing (shown as 130 in Figure 1) in contact with the tibial tray, the tibial bearing having a bearing surface for interfacing with the articular surface of the femoral component.

[0130] FIG. 43 is an upper front perspective view corresponding to the tibial cone 4200 of FIG. 42, in which the tibial cones 4200a-4200f decrease in size by eliminating incremental steps, which makes the up and down size progression intuitive and streamlines the instrument.

[0131] In some sizes of the tibial cones of the present invention, a distal portion of the anterior and / or posterior walls may be removed to form a notch for receiving the tibial component fin. This is shown in FIG 44, which illustrates the notch 4480a of the tibial cone 4400a. Referring to FIG 44, the tibial cone 4400a has a first end surface 4420a, a second end surface 4430a, a stepped outer surface 4440a extending from the first end surface 4420a to the second end surface 4430a, and an inner surface defining a passageway extending from the first end surface 4420a to the second end surface 4430a, the outer surface 4440a of the cone 4400a being configured to be placed within the femoral cavity such that the first end surface 4420a is flush with or recessed from the resected tibial surface. The first end surface 4420a lies in an axial plane defined by the first end surface 4420a and an outermost edge 4470a of the first end surface 4420a. The tibial cone 4400a has a notch 4480a for receiving a tibial component fin.

[0132] 44, the tibial cone 4400b (which is larger in size than the tibial cone 4400a) has a first end surface 4420b, a second end surface 4430b, a stepped outer surface 4440b extending from the first end surface 4420b to the second end surface 4430b, and an inner surface defining a passageway extending from the first end surface 4420b to the second end surface 4430b, the outer surface 4440b of the cone 4400b being configured to be received within the femoral cavity such that the first end surface 4420b is flush with or recessed from the resected tibial surface. The first end surface 4420b lies in an axial plane defined by the first end surface 4420b and an outermost edge 4470b of the first end surface 4420b. The tibial cone 4400b has a notch 4480b for receiving the tibial component fin.

[0133] The tibial cones 4400a and 4400b can be used in a prosthetic system that includes a tibial implant having a body and a stem, the stem being positioned within the passageway of the cones 4400a and 4400b as in Figure 37B. The tibial cones 4400a and 4400b can be used in a prosthetic system that includes a tibial tray as shown in Figure 2 and a tibial bearing (shown as 130 in Figure 1) in contact with the tibial tray, the tibial bearing having a bearing surface for coupling with the articular surface of a femoral component.

[0134] In some sizes of tibial cones of other embodiments of the invention, a distal portion of the anterior and / or posterior walls may be removed to accommodate a tibial component fin. This is shown in FIGURE 45, which illustrates a notch 4580a in the tibial cone 4500a. Referring to FIGURE 45, the tibial cone 4500a has a first end surface 4520a, a second end surface 4530a, a smooth outer surface 4540a extending from the first end surface 4420a to the second end surface 4530a, and an inner surface defining a passageway extending from the first end surface 4520a to the second end surface 4530a, the outer surface 4540a of the cone 4500a being configured to be placed within the femoral cavity such that the first end surface 4520a is flush with or recessed from the resected tibial surface. The first end surface 4520a lies in an axial plane defined by the first end surface 4520a and an outermost edge 4570a of the first end surface 4520a. The tibial cone 4500a has a notch 4580a for receiving a tibial component fin.

[0135] 45, the tibial cone 4500b (which is larger in size than the tibial cone 4500a) has a first end surface 4520b, a second end surface 4530b, a smooth outer surface 4540b extending from the first end surface 4520b to the second end surface 4530b, and an inner surface defining a passageway extending from the first end surface 4520b to the second end surface 4530b, the outer surface 4540b of the cone 4500b being configured to be received within the femoral cavity such that the first end surface 4520b is flush with or recessed from the resected tibia surface. The first end surface 4520b lies in an axial plane defined by the first end surface 4520b and an outermost edge 4570b of the first end surface 4520b. The tibial cone 4500b has a notch 4580b for receiving the tibial component fin.

[0136] The tibial cones 4500a and 4500b can be used in a prosthetic system that includes a tibial implant having a body and a stem, the stem being positioned within the passageway of the cones 4500a and 4500b as in Figure 37B. The tibial cones 4500a and 4500b can be used in a prosthetic system that includes a tibial tray as shown in Figure 2 and a tibial bearing (shown as 130 in Figure 1) in contact with the tibial tray, the tibial bearing having a bearing surface for coupling with the articular surface of the femoral component.

[0137] The increased size range expands the potential use of cones in revision knee arthroplasty. Current cones are limited in size and have a large gap between sizes that are too small and push in implants that do not maximize contact, and sizes that require additional bone removal to fit the implant. Providing the smaller cone sizes of the present invention expands the market for cone use, making it an attractive, premium-priced, high-value product for manufacturers.

[0138] Additionally, the above system and implant streamlines the flow of surgery. For the tibia, the distal size is established with a cylindrical reamer, and then a cone broach is used to ensure maximum support and minimize bone removal. The same is true for the femur after engagement with the proximal femoral shaft. The system of the present invention allows any size cone to be used with any size stem. This greatly facilitates expanding the range of cone use in revision cases, expanding market opportunities. For example, using a smaller cone for any size patient provides a better option compared to using bone grafts, cement, or additional bone removal to fit current non-anatomical shaped and sized cones.

[0139] The cone may be formed from metal alloys such as titanium alloys (e.g., titanium-6-aluminum-4-vanadium), cobalt-chromium alloys, stainless steel alloys, and tantalum alloys, non-resorbable ceramics such as aluminum oxide and zirconia, non-resorbable polymeric materials such as polyethylene, or composite materials such as carbon fiber reinforced polymers (e.g., polysulfone). In some configurations, the cone may be formed from a tantalum-based porous material, or other metals coated with a tantalum-based porous metal or other porous coating.

[0140] F. Cadaveric Verification Cadaveric validation of these models clearly demonstrated improved surgical flow and performance, feel, and fit over current market devices. The same device can be used for both the cone and sleeve.

[0141] 24A and 24B show a tibial sleeve assembly 2410 with a sleeve 2420, a stem 2430, and an adaptor 2440 for connecting the sleeve 2420 and the stem 2430. An inserter 2460 can be used to insert the tibial sleeve assembly 2410 into the prepared tibia. FIG. 24C shows a range of sizes of sleeves 2420a-g, an adaptor 2440, and a range of sizes of stems 2430a, 2430b, and 2430c. The tibial sleeve assembly (see FIGS. 24A and 24B) and a detailed view of the anatomically shaped tibial sleeve assembly (FIG. 24C) show how the sleeve is anatomically shaped with the offset of the stem based on the actual anatomy.

[0142] 25A-25C, a femoral sleeve assembly 2510 is shown, which includes a sleeve 2520d, a stem 2530, and an adapter 2540 for connecting the sleeve 2520a and the stem 2530. FIG. 25A shows a range of sizes of sleeves 2520a-2520f. FIG. 25B and FIG. 25C are detailed views of anatomically shaped femoral sleeves 2520a-2520f. It can be seen how the sleeves are anatomically shaped with the offset and angle of the stem based on the actual anatomical structure.

[0143] A typical femoral defect 2610 and a tibial defect 2620 in a revision knee arthroplasty are shown in FIG.

[0144] A simplified tibia preparation technique is as follows: Drill the distal tibia 2710 with a reamer 2715 for cortical contact (see FIG. 27A), a tibial broach 2720, and a trial stem 2730 (see FIG. 27B), and press-fit the broach 2720 and trial stem 2730 with an inserter 2750 (see FIG. 27C). The sleeve was designed so that any size sleeve can be used with any size stem. It can be seen how the sleeve 2820 matches the anatomy of the proximal tibia and creates an optimal environment for stabilization and bone ingrowth (see FIG. 28A and FIG. 28B).

[0145] The press-fit process for the tibial sleeve 2820 and stem 2830 construct is as follows: Slots 2825 extending from the passageway 2822 are formed in the upper surface of the sleeve 2820 to allow for additional rotational adjustment of the tibial tray for further improved tibial coverage that minimizes any overhang of the components (see FIGS. 29A and 29B).

[0146] A simplified tibia preparation technique is as follows: Drill the femur 3010 with a reamer 3015 (see FIG. 30A), femoral broach 3020, and trial stem 3330 (FIG. 30B) for cortical contact. The sleeve was designed so that any size sleeve can be used with any size stem. Notice how the sleeve 3120 matches the distal femoral anatomy 3010 and creates an optimal environment for stabilization and bone ingrowth (see FIG. 31A and FIG. 31B).

[0147] The present disclosure represents the development of a novel methodology that significantly advances understanding of the anatomy of the proximal tibia and distal femur. This method facilitates the design of an innovative revision knee arthroplasty system featuring an anatomically shaped metaphyseal sleeve. These novel sleeves grow based on actual anatomy in the medial-lateral and anterior-posterior directions, resulting in significantly improved contact with the underlying bone, reducing bone removal and improving fit and fixation. Moreover, the offset of the stem relative to the sleeve is achieved in a manner that allows for optimized fit, minimizing the risk of iatrogenic fracture and reducing component misalignment. The system is capable of providing an intuitive and streamlined workflow, thereby improving the user experience. The ability to use any size sleeve with any size stem while preserving bone may expand the potential patient population that can benefit from the use of sleeves during revision knee arthroplasty.

[0148] Considering the principles and example embodiments described and illustrated herein, it can be appreciated that the arrangements and details of the example embodiments can be improved without departing from the principles. In addition, although the above discussion has focused on a particular embodiment, other configurations are possible. In particular, although the present specification uses expressions such as "one embodiment" or "another embodiment," such words are generally understood to refer to possible embodiments, and are not intended to limit the present invention to the configuration of a particular embodiment. When such words are used in this application, it means that multiple identical or different embodiments can be combined to form another embodiment. Generally, any embodiment referred to in this application can be freely combined with one or more other embodiments referred to in this application, and any number of features of different embodiments can be combined with each other, unless otherwise specified.

[0149] Although the present invention has been described in some detail with reference to specific embodiments, those skilled in the art will appreciate that the present invention may be practiced in other embodiments than those described herein, and that the embodiments described herein are presented for purposes of illustration and not limitation of the present invention, and therefore the scope of the appended claims should not be limited to the description of the embodiments contained therein.

Claims

1. 1. A prosthetic system for providing motion between a first bone and a second bone of a joint, comprising: a support structure having a first end face, a second end face, an outer surface extending from the first end face to the second end face, and an inner surface defining a passageway extending from the first end face to the second end face; an outer surface of the support structure configured to be placed within the cavity of the first bone such that the first end surface is flush with or recessed from a surface of the first bone; the first end surface lies in an axial plane defined by the first end surface and an outermost edge of the first end surface; The longitudinal axis of the passageway of the support structure is offset from the geometric center point of the axial surface. A prosthetic system characterized by:

2. the first bone is a tibia; The joint is the knee. The prosthetic system of claim 1 .

3. a tibial implant having a body and a stem extending away from the body; the stem is disposed within the passage of the support structure; The prosthetic system of claim 2.

4. the body of the tibial implant is a tibial tray; The prosthetic system of claim 3.

5. the first bone is a femur; the joint is the knee, The prosthetic system of claim 1 .

6. a longitudinal axis of the passageway of the support structure forms an oblique angle with a normal to the axial plane; The prosthetic system of claim 1 .

7. The longitudinal axis of the passage of the support structure is an intramedullary axis having a first intersection point determined by a first intersection of a first reference axial plane located at a first distance from an end surface of the first bone before resection with an axis of inertia of the first bone, and a second intersection point determined by a second intersection of a second reference axial plane located at a second distance different from the first distance from the end surface of the first bone before resection with the axis of inertia of the first bone. The prosthetic system of claim 1 .

8. a prosthetic implant having a body and a stem extending away from the body; the stem is disposed within the passage of the support structure; The prosthetic system of claim 1 .

9. A step is formed on the outer surface of the support structure. The prosthetic system of claim 1 .

10. the outer surface of the support structure is smooth; The prosthetic system of claim 1 .

11. the outer surface of the support structure is roughened; The prosthetic system of claim 1 .

12. the outer surface of the support structure comprises a porous in-growth material; The prosthetic system of claim 1 .

13. the support structure includes a wall between the outer surface and the inner surface; the wall has one or more notches extending away from the first end face; The prosthetic system of claim 1 .

14. the support structure includes a wall between the outer surface and the inner surface; the wall has one or more notches extending away from the second end face; The prosthetic system of claim 1 .

15. the support structure includes a wall between the outer surface and the inner surface; the thickness of the front portion of the wall is less than the thickness of other portions of the wall adjacent to the front portion of the wall; The prosthetic system of claim 1 .

16. the outermost edge of the first end surface is the periphery of the first end surface; The prosthetic system of claim 1 .

17. the first end surface has one or more slots extending from the passage; each said slot being sized to receive a stabilizing arm of a stem of a prosthetic implant; The prosthetic system of claim 1 .

18. 1. A kit for a prosthetic system for providing motion between a first bone and a second bone of a joint, comprising: (i) a first support structure having a first end face, a second end face, an outer surface extending from the first end face to the second end face, and an inner surface defining a passageway extending from the first end face to the second end face; an outer surface of the first support structure configured to be placed within the cavity of the first bone such that the first end surface is flush with or recessed from a surface of the first bone; the first end surface lies in an axial plane defined by the first end surface and an outermost edge of the first end surface; a longitudinal axis of the passageway of the first support structure is offset from a geometric center point of the axial surface; (ii) the kit further comprises one or more additional support structures, each having an end surface; an end surface of each of the additional support structures lies in an additional axial plane defined by the end surface of the additional support structure and a boundary of the end surface of the additional support structure; Each longitudinal axis of the passageway through each of the additional support structures is offset from a geometric center point of the additional axial surface. A kit characterized by:

19. 1. A method for manufacturing a prosthetic support structure for implantation into a cavity in the end of a bone, comprising: forming a support structure having an outer surface sized to fit within the cavity and an inner surface defining a prosthetic support structure passageway; Including, the passageway is sized to receive the stem of a prosthetic implant; the passage extends from a first end surface to a second end surface of the support structure; the first end surface of the support structure lies in an axial plane defined by the first end surface and an outermost edge of the first end surface; the passageway has a longitudinal axis; The intersection of the axial plane and the longitudinal axis of the passage is (i) acquiring an image of a reference bone; (ii) orienting a first reference axial plane on the image, the first reference axial plane being located at a first distance from an end surface of the reference bone; (iii) orienting a second reference axial plane on the image, the second reference axial plane being located at a second distance from the end surface of the reference bone, the second distance being different from the first distance; (iv) Orienting the intramedullary axis on the image by connecting a first intersection point determined by a first intersection portion between the inertial axis of the reference bone and the first reference axial plane and a second intersection point determined by a second intersection portion between the inertial axis of the reference bone and the second reference axial plane; (v) orienting a reference resection plane on the axial image of the reference bone, the reference resection plane having a boundary defined by the axial image of the reference bone; (vi) orienting a reference intersection point between the reference resection plane and the intramedullary axis on the image. This was determined by The reference spatial relationship between the reference intersection point and the boundary of the reference resection surface corresponds to the spatial relationship between the intersection point on the axial plane and the outermost edge of the first end surface of the support structure. A method characterized by:

Images