Joint endoprosthesis

An endoprosthesis having congruent engagement between engaged bearing surfaces, comprising:

• A. A first prosthesis for being secured to a first bone and providing a first bearing surface the shape of which is a smooth, continuous surface formed by a series of segments of surfaces of revolution the respective shapes of which are generated by rotating a common generating curve around a plurality of predetermined generating axes at predetermined plurality of predetermined generating axes at predetermined respective angles of rotation, one of said series of segments of surfaces of revolution being the primary load bearing segment;
• B. a second prosthesis including:
• (i) a platform or fixturing component for being secured to a second bone and providing a second bearing surface;
• (ii) an intermediate bearing component for being positioned intermediate said platform or fixturing component and said first prosthesis, said intermediate bearing component being received and supported rotatably by said platform or fixturing component in substantially congruent area rotational engagement to permit rotational movement between the first and second bones and further provided with a third bearing surface for substantially congruent area sliding engagement with said first bearing surface of said first prosthesis to permit rotational movement of one bone around the other bone, said third bearing surface being a primary load bearing surface the shape of which is generated by rotating said common generating curve through a predetermined angle about a predetermined generating axis at the same pair of major generating radii at which said common generating curve is rotated to generate said primary load bearing segment whereby said third bearing surface congruently matches said primary load bearing segment of said first prosthesis.

An improved knee prosthetic joint with congruent bearing surface engagement and for providing only two degrees of freedom of rotational movement between a patella and a femur, said patella having an axis and wherein said prosthetic knee joint is periodically under compressive loads transmitted thereto by such bones, which comprises:

• a patella fixturing component for being secured to at least a remnant of the patella and providing a first bearing surface;
• a femoral component for being secured to the distal end of the femur and providing a second bearing surface which is a smooth, continous surface formed by a series of segments of surfaces of revolution the respective shapes of which are generated by rotating a common generating curve around a plurality of first predetermined generating axes at predetermined respective pairs of major generating radii and through predetermined respective angles of rotation;
• one of said series of segments of surfaces of revolution being the femoral primary load bearing segment;
• a patella intermediate bearing component intermediate said patella fixturing component and said femoral component and provided with:
• (i) a third bearing surface substantially congruent with said first bearing surface and for substantially congruent area rotational engagement therewith to permit relative rotational movement of said patella fixturing component with respect to said patella intermediate bearing component and said femoral component about a second predetermined axis not parallel to said first predetermined generating axes and thereby providing the first degree of said only two degrees of freedom of rotational movement and wherein said second predetermined axis is substantially parallel to the axis of the patella,
• and
• (ii) a fourth bearing surface, comprised of less than half a surface of revolution, substantially congruent with said second bearing surface and for substantially congruent sliding engagement therewith to permit relative rotational movement of said patella fixturing component and said patella intermediate bearing component with respect to said femoral component about said first predetermined generating axes and thereby providing the second degree of said only two degrees of freedom of rotational movement and inhibiting rotation of said patella intermediate bearing component relative to said femoral component about any axes but said first predetermined generating axes upon said bearing surfaces being in engagement due to said compressive loads being transmitted to said knee prosthetic joint.

An improved knee prosthetic joint for allowing all normal degrees of freedom of joint rotational movement between the tibia and femur and providing congruent bearing surface engagement during predetermined portions of all such rotational movement, but upon compressive load being applied to said joint, said joint providing only two degrees of freedom of rotational movement between said tibia and femur, said tibia having a long axis, which comprises:

• a tibial platform component for being secured to the proximal end of the tibia and providing a first bearing surface;
• a femoral component for being secured to the distal end of the femur and providing a second bearing surface which is a smooth, continuous surface formed by a series of segments of surfaces of revolution the respective shapes of which are generated by rotating a common generating curve around a plurality of generating axes at respective pairs of major generating radii and through respective angles of rotation, one of said segments of surfaces of revolution being the primary load bearing segment;
• an intermediate tibial bearing component intermediate said tibial platform component and said femoral component and provided with:
• (i) a third bearing surface substantially congruent with said first bearing surface and for substantially congruent area rotational engagement therewith to permit relative rotational movement of said tibial platform component with respect to said intermediate tibial bearing component and said femoral component about a second predetermined axis not parallel to said plurality of generating axes and thereby providing the first degree of said only two degrees of freedom of rotational movement, and where said second predetermined axis is generally parallel to the long axis of the tibia, and
• (ii) a fourth bearing surface defined by rotating said common generating curve through a predetermined angle about a predetermined generating axis at the same pair of major generating radii at which said common generating curve is rotated to define said primary load bearing segment whereby said fourth bearing surfce congruently matches said primary load bearing segment for substantially congruent sliding engagement therewith during predetermined portions of such engagement to permit all other of said normal degrees of freedom of joint rotational movement in the absence of said sufficient compressive load, but upon said compressive load, being applied to said knee prosthetic joint, said fourth and second bearing surfaces providing only said second degree of said only two degrees of freedom of rotational movement.

An improved endoprosthesis for providing the articular surfaces between a first bone and a second bone, comprising:

• a first endoprosthesis component for being secured to said first bone and providing a first articular surface;
• a second endoprosthesis component for being secured to said second bone and for providing a second articular surface for articulating with said first articular surface;
• said first articular surface being a smooth continuous surface formed by a series of segments of tangent surfaces of revolution the respective shapes of which are generated by rotating a common generating curve around a plurality of predetermined generating axes at predetermined respective pairs of major generating radii and through predetermined respective angles of rotation;
• and
• said second articular surface being generated by rotating said common generating curve through a predetermined angle about a predetermined generating axis at the same pair of major generating radii at which said common generating curve is rotated to generate one segment of said first articular surface whereby upon said second articular surface articulating with said first articular surface, said second articular surface articulating with said one segment of said first articular surface in substantially area sliding contact and articulating with said remaining segments of said first articular surface in substantially line sliding contact.

A knee endoprosthesis having congruent engagement between engaged bearing surfaces comprising:

• A. A femoral prosthesis for being secured to the distal end of the femur and providing a femoral bearing surface the shape of which is a smooth, continuous surface formed by a series of segments of tangent surfaces of revolution the respective shapes of which are generated by rotating a common generating curve around a plurality of predetermined generating axes at predetermined respective pairs of major generating radii and through predetermined respective angles of rotation, one of said series of segments of surfaces of revolution being the femoral primary load bearing segment;
• and
• B. A patella prosthesis including a patella load bearing surface for engaging said femoral bearing surface in substantially congruent sliding engagement to permit rotational movement of said patella round the distal end of the femur, said patella bearing surface including a patella primary load bearing surface segment the shape of which is defined by rotating said common generating curve through a pedetermined angle about a predetermined generating axis at the same pair of major generating radii at which said common generating curve is rotated to define said femoral primary load bearing segment whereby said patella primary load bearing segment congruently matches said femoral primary load bearing segment.

A knee endoprosthesis having substantially congruent area sliding engagement between engaged bearing surfaces upon said endoprosthesis being under heavy joint compressive loads, comprising:

• A. A femoral prosthesis for being secured to the distal end of the femur and providing a femoral bearing surface the shape of which is smooth, continuous surface formed by a series of segments of tangent surfaces of revolution the respective shapes of which are generated by rotating a common generating curve around a plurality of predetermined generating axes at predetermined respective pairs of major generating radii and through predetermined respective angles of rotation, one of said series of segments of surfaces of revolution being the femoral primary load bearing segment;
• and
• B. A tibial prosthesis including a tibial primary load bearing surface for engaging said femoral load bearing surface in sliding engagement to permit rotational movement of the tibia around the distal end of the femur and said tibial primary load bearing surface engaging said femoral primary load bearing segment in sliding engagement upon said endoprosthesis being under said compressive loads, the shape of said tibial primary bearing surface being defined by rotating said common generating curve though a predetermined angle about a predetermined generating axis at the same pair of major generating radii at which said common generating curve is rotated to define said femoral primary load bearing segment whereby said tibial primary bearing surface substantially congruently matches said femoral primary load bearing segment and engages said femoral primary load bearing segment in substantially congruent area sliding contact upon said endoprosthesis being under said compressive loads.

A knee endoprosthesis having congruent engagement between engaged bearing surfaces comprising:

• A. A femoral prosthesis for being secured to the distal end of the femur and providing a femoral bearing surface the shape of which is a smooth, continuous surface formed by a series of segments of surfaces of revolution the respective shapes of which are generated by rotating a common generating curve around a plurality of predetermined generating axes at predetermined respective pairs of major generating radii and through predetermined respective angles of rotation, one of said series of segments of surfaces of revolution being the femoral primary load bearing segment;
• B. A patella prosthesis including a patella load bearing surface for engaging said femoral bearing surface in substantially congruent sliding engagement to permit rotational movement of said patella round the distal end of the femur, said patella bearing surface including a patella primary load bearing surface segment the shape of which is defined by rotating said common generating curve through a predetermined angle about a predetermined generating axis at the same pair of major generating radii at which said common generating curve is rotated to define said femoral primary load bearing segment whereby said patella primary load bearing segment congruently matches said femoral primary load bearing segment;
• C. A tibial prosthesis including a tibial primary load bearing surface for engaging said femoral load bearing surface in substantially congruent sliding engagement to permit rotational movement of the tibia around the distal end of the femur, the shape of said tibial primary bearing surface being defined by rotating said common generating curve through a predetermined angle about a predetermined generating axis at the same pair of major generating radii at which said common generating curve is rotated to define said femoral primary load bearing segment whereby said tibial primary bearing surface congruently matches said femoral primary load bearing segment.

A knee endoprosthesis having congruent engagement between engaged bearing surfaces, comprising:

• A. A femoral prosthesis for being secured to the distal end of the femur and providing a first bearing surface the shape of which is a smooth, continuous surface formed by a series of segments of surfaces of revolution the respective shapes of which are generated by rotating a common generating curve around a plurality of predetermined generating axes at predetermined respective angles of rotation, one of said series of segments of surfaces of revolution being the primary load bearing segment;
• and
• B. A patella prosthesis including:
• (i) a patella fixturing component for being secured to at least a remnant of the patella and providing a second bearing surface;
• (ii) an intermediate patella bearing component for being positioned intermediate said patella fixturing component and said femoral prosthesis, said intermediate patella bearing component being received and supported rotatably by said patella fixturing component and providing a third bearing surface for rotatably engaging said second bearing surface provided on said patella fixturing component in substantially congruent area rotational engagement to permit rotational movement between the patella and the distal end of the femur and further provided with a fourth bearing surface provided on said patella prosthesis in substantially congruent sliding area engagement to permit rotational movement of said patella around the distal end of said femur, said fourth bearing surface including a primary load bearing surface segment the shape of which is generated by rotating said common generating curve through a predetermined angle about a predetermined generating axis at the same pair of major generating radii at which said common generating curve is rotated to generate said primary load bearing segment whereby said primary load bearing surface segment congruently matches said primary load bearing segment of said femoral prosthesis.

A knee endoprosthesis having congruent and incongruent sliding engagement between engaged bearing surfaces, comprising:

• A. A femoral prosthesis for being secured to the distal end of the femur and providing a first bearing surface the shape of which is a smooth, continuous surface formed by a series of segments of surfaces of revolution the respective shapes of which are generated by rotating a common generating curve around a plurality of predetermined generating axes at predetermined respective angles of rotation, one of said series of segments of surfaces of revolution being the primary load bearing segment;
• B. A tibial prosthesis including:
• (i) a tibial platform component for being secured to the proximal end of a tibia and providing a second bearing surface;
• (ii) an intermediate tibial bearing component for being positioned intermediate said tibial platform component and said femoral prosthesis, said intermediate tibial bearing component being received and supported rotatably by said tibial platform component in substantially congruent area rotational engagement to permit rotational movement between the tibia and the femur and further provided with a third bearing surface generated by rotating said common generating curve through a predetermined angle about a predetermined generating axis at the same pair of major generating radii at which said common generating curve is rotated to generate said primary load bearing segment, said third bearing surface for engaging said primary load bearing segment, in substantially congruent area sliding engagement and for engaging other of the remaining segments of said series of segments of surfaces of revolution of said first bearing surface in substantially line contact sliding engagement to permit rotational movement of the tibia around the distal end of the femur.

A knee endoprosthesis having congruent engagement between engaged bearing surfaces, comprising:

• A. A femoral prosthesis for being secured to the distal end of the femur and providing a first bearing surface the shape of which is a smooth, continuous surface formed by a series of segments of surfaces of revolution the respective shapes of which are generated by rotating a common generating curve around a plurality of predetermined generating axes at predetermined respective angles of rotation, one of said series of segments of surfaces of revolution being the primary load bearing segment;
• B. A patella prosthesis including:
• (i) a patella fixturing component for being secured to at least a remnant of the patella and providing a second bearing surface;
• (ii) an intermediate patella bearing component for being positioned intermediate said patella fixturing component and said femoral prosthesis, said intermediate patella bearing component being received and supported rotatably by said patella fixturing component and providing a third bearing surface for rotatably engaging said second bearing surface provided on said patella fixturing component in substantially congruent area rotational engagement to permit rotational movement between the patella and the distal end of the femur and further provided with a fourth bearing surface provided on said patella prosthesis in substantially congruent sliding area engagement to permit rotational movement of said patella around the distal end of said femur, said fourth bearing surface including a primary load bearing surface segment the shape of which is generated by rotating said common generating curve through a predetermined angle about a predetermined generating axis at the same pair of major generating radii at which said common generating curve is rotated to generate said primary load bearing segment whereby said primary load bearing surface segment congruently matches said primary load bearing segment of said femoral prosthesis;
• C. A tibial prosthesis including:
• (i) a tibial platform component for being secured to the proximal end of said tibia and providing a fifth bearing surface;
• (ii) an intermediate tibial bearing component for being positioned intermediate said tibial platform component and said femoral prosthesis, said intermediate tibial bearing component being received and supported rotatably by said tibial platform component in substantially congruent area rotational engagement to permit rotational movement between the tibial and the femur and further provided with a sixth bearing surface for substantially congruent area sliding engagement with said firtst bearing surface of said femoral prosthesis to permit rotational movement of the tibia around the distal end of the femur, said sixth bearing surface being a primary load bearing surface the shape of which is generated by rotating said common generating curve through a predetermined angle about a predetermined generating axis at the same pair of major generating radii at which said common generating curve is rotated to generate said primary load bearing segment whereby said sixth bearing surface congruently matches said primary load bearing segment of said femoral prosthesis.

A knee endoprosthesis, comprising:

• A. A femoral prosthesis for being secured to the distal end of the femur and providing a femoral bearing surface the shape of which is generated by rotating a common generating curve around a first predetermined generating axis at a first predetermined respective pair of major generating radii and through a first predetermined respective angle of rotation;
• B. A patella prosthesis including a patella load bearing surface for engaging said femoral bearing surface in sliding engagement to permit rotational movement of said patella around the distal end of the femur, said patella bearing surface generated by rotating said common generating curve around a second predetermined generating axis at a second predetermined pair of major generating radii and through a second predetermined angle of rotation;
• C. A tibial prosthesis including a tibial load bearing surface for engaging said femoral load bearing surface in sliding engagement to permit rotational movement of the tibia around the distal end of the femur, said tibial load bearing surface generated by rotating said common generating curve around a third predetermined generating axis at a third pair of major generating radii and through a third predetermined angle of rotation;
• and
• D. upon said patella load bearing surface and said tibial load bearing surface engaging said femoral load bearing surface in said sliding engagement, said patella and said tibial load bearing surfaces engaging said femoral load bearing surface in at least line contact thereby reducing wear of said load bearing surfaces due to said sliding engagement.

An endoprosthesis, comprising:

• A. A first prosthetic component for being secured to a first bone and providing a first bearing surface the shape of which is generated by rotating a common generating curve around the first predetermined generating axis at a first predetermined respective pair of major generating radii and through a first predetermined respective angle of rotation;
• B. A second prosthetic component for being secured to a second bone and providing a second load bearing surface for engaging said first load bearing surface in sliding engagement to permit movement of said first bone with respect to said second bone, said second load bearing surface generated by rotating said common generating curve around a second predetermined generating axis at a second predetermined pair of major generating radii and through a second predetermined angle of rotation;
• C. A third prosthetic component for being secured to a third bone providing a third load bearing surface for engaging said first load bearing surface in sliding engagement to permit movement of said third bone with respect to said first bone, said third load bearing surface generated by rotating said common generating curve around a third predetermined generating axis at a third pair of major generating radii and through a third predetermined angle of rotation;
• and
• D. Upon said second and third load bearing surfaces engaging said first load bearing surface in said sliding engagement, said second and third load bearing surfaces engaging said first load bearing surface in at least line contact thereby reducing wear of said load bearing surfaces due to said sliding engagement.

An improved prosthetic joint for providing movement between a first bone and a second bone, said prosthetic joint periodically being under compressive load transmitted thereto by said bones, which comprises:

• a first component for being secured to said first bone and providing a first bearing surface;
• a second component for being secured to said second bone and providing a second bearing surface;
• an intermediate bearing component intermediate said first and second components provided with:
• (i) a third bearing surface substantially congruent with said first bearing surface and for substantially congruent sliding engagement therewith during joint articulation.
• (ii) a fourth bearing surface incongruent with predetermined portions of said second bearing surface and congruent with predetermined other portions of said second bearing surface, said fourth bearing surface for sliding engagement with said second bearing surface to permit movement of said first and intermediate bearing components with respect to said second bone.

A knee endoprothesis, comprising:

• A. A femoral prosthesis for being secured to the distal end of the femur and providing a femoral bearing surface the shape of which is a smooth, continuous surface formed by at least first, second and third segments of surfaces of revolution the respective shapes of which are generated by rotating a common generating curve around at least three respective predetermined generating axes at three predetermined respective pairs of major generating radii and through three predetermined respective angles of rotation, said second segment of a surface of revolution being the femoral primary load bearing segment;
• B. (i) A patella prosthesis for being secured to at least a remnant of the patella and providing a patella load bearing surface the shape of which is defined by rotating said common generating curve through a predetermined angle around a predetermined generating axis at the same pair of major generating radii at which said common generating curve is rotated to define said femoral primary load bearing surface,
• (ii) upon said patella rotating around the distal end of said femur, said patella load bearing surface engaging said femoral bearing surface in sliding engagement with said patella load bearing surface engaging said first segment of a surface of revolution forming said femoral bearing surface in at least line contact and engaging said second segment of surface of revolution forming said femoral bearing surface in area contact;
• and
• C. (i) a tibial prosthesis for being secured to the proximal end of the tibia and providing a tibial load bearing surface the shape of which is defined by rotating said common generating curve through a predetermined angle about a predetermined major axis at the same pair of major generating radii at which said common generating curve is rotated to define said femoral primary load bearing surface;
• (ii) upon said tibia rotating around the distal end of said femur, said tibial load bearing surface engaging said femoral bearing surface in sliding engagement with the tibial load bearing surface engaging said second segment of surface of revolution forming said femoral bearing surface in area contact and engaging said third segment of surface of revolution forming said femoral bearing surface in at least line contact.