Patent ID: 8858642

Claim:
A knee joint prosthesis assembly comprising: a femoral component having a medial and a lateral condyle portion connected by a patellar track portion, the femoral component forming an opening between the medial and lateral condyles; a unitary tibial component having a medial portion that includes a first engagement structure and a lateral portion that includes a second engagement structure; a medial bearing having a third engagement structure formed thereon that selectively engages the first engagement structure; and a lateral bearing separately formed and independent from the medial bearing and having a fourth engagement structure formed thereon that selectively engages the second engagement structure; wherein one of the medial and lateral bearings is fixed relative to the tibial component and the other of the medial and lateral bearings is a mobile bearing component; wherein the mobile bearing component includes: a fixed portion having a superior surface configured to cooperate with one of the medial or lateral condyle portions of the femoral component, and having the third engagement structure or the fourth engagement structure that is configured to statically engage the tibial component; and a mobile bearing portion having a superior articulating surface configured to cooperate with said medial or lateral condyle portions of the femoral component, said mobile bearing portion being configured to slidably advance along a superior surface of the tibial component.