Modular knee joint prosthesis

A knee joint prosthesis comprising:

• a femoral component adapted to be implanted on the condylar portion of the femur and having a pair of laterally spaced-apart condylar portions, and an intercondylar portion interconnecting the condylar portions and defining an intercondylar recess having lateral side walls spaced-apart a predetermined distance, an anterior stop surface and a posterior camming member;
• and
• a tibial component comprising a tibial insert of plastic material fitted and held in a tibial tray adapted to be attached to the resected tibia, the tibial insert having a superior aspect comprising spaced-apart concavities and a tibial eminence therebetween and receivable in the intercondylar recess of the femoral component, and attachment means for attachment of the tibial insert to the tibial tray, the attachment means comprising a pair of dovetail-shaped bosses extending in parallel on the superior surface of the tibial tray and a recess extending perpendicularly to the bosses, and a like dimensioned pair of dovetail-shaped grooves formed in the inferior surface of the plastic tibial insert and a boss extending perpendicularly to the grooves, the boss on the insert having reinforcing metal inserts extending from the surface of the boss into the insert, the eminence being adapted to be received in the intercondylar recess of the femoral component, the eminence having lateral surfaces, an anterior surface and a posterior surface, the relative positions and shapes of the anterior and posterior surfaces of the eminence and recess of the prosthesis as implanted in the knee joint being such as to permit relatively free antero-posterior translation of the components while restraining excessive anterior and posterior movements, and wherein the eminence includes lateral surfaces having portions essentially parallel to the lateral side walls of the recess defining a width of the eminence substantially narrower than the distance between the spaced-apart lateral side walls and portions angled with respect to anterior-posterior planes for enabling medial/lateral translation and substantial varus/valgus angulation and relative rotation between the tibial component and the femoral component throughout a substantial portion of the range of flexion.

A knee joint prosthesis comprising:

• a femoral component adapted to be implanted on the condylar portion of the femur and having a pair of laterally spaced-apart condylar portions and an intercondylar portion interconnecting the condylar portions and defining an intercondylar recess having lateral side walls and a posterior bearing surface;
• and
• a tibial component adapted to be implanted on the tibial plateau and including a substantially flat platform portion having on its superior surface a pair of laterally spaced-apart concavities adapted to receive in nested relation the respective condylar portions of the femoral component, and an eminence extending superiorly from the platform portion and generally between the concavities for reception in the intercondylar recess of the femoral component, the eminence having lateral surfaces, an anterior surface and a posterior bearing surface, the relative positions and shapes of the anterior and posterior surfaces of the eminence and recess of the prosthesis as implanted in the knee joint being such as to permit relatively free relative antero-posterior translation of the components while restraining excessive anterior and posterior movements between the components, and wherein the respective posterior bearing surfaces of the tibial component and the femoral component are shaped so that as flexion of the knee increases, the force-transmitting contact area between such bearing surfaces increases.

A knee joint prosthesis comprising:

• a femoral component adapted to be implanted on the condylar portion of the femur and having a pair of laterally spaced-apart condylar portions, and an intercondylar portion interconnecting the condylar portions and defining an intercondylar recess having lateral side walls spaced apart a predetermined distance, an anterior stop surface and a posterior camming member;
• and
• a tibial component comprising a tibial insert of plastic material fitted and held in a tibial tray adapted to be attached to the resected tibia, the tibial insert having a superior aspect comprising spaced-apart concavities for articulation with the condylar portions of the femoral component and a tibial eminence therebetween and receivable in the intercondylar recess of the femoral component, the eminence having lateral surfaces, an anterior surface and a posterior surface, the relative positions and shapes of the anterior and posterior surfaces of the eminence and recess of the prosthesis as implanted in the knee joint being such as to permit relatively free antero-posterior translation of the components while restraining excessive anterior and posterior movements, and wherein the eminence includes lateral surfaces having portions defining a width of the eminence substantially narrower than the distance between the spaced-apart lateral side walls and portions angled with respect to anterior-posterior planes for enabling medial/lateral translation and substantial varus/valgus angulation and relative rotation between the tibial component and the femoral component throughout a substantial portion of the range of flexion, the respective posterior bearing surfaces of the tibial component and the femoral component being so shaped that as flexion of the knee increases, the force-transmitting contact area between such bearing surfaces increases.