Patellar contact forces with and without patellar resurfacing in total knee arthroplasty

Patellar contact forces were measured in 7 fresh-frozen cadaver knees during continuous flexion-extension cycling for the normal knee and after total knee arthroplasty without and with patellar resurfacing using 2 prosthesis systems with different designs for the femoral and patellar components. Analysis of variance with specimen as a repeated measure was used to examine the effect of contact surface. When compared to normal knees, total knee arthroplasty without patellar resurfacing resulted in no change in patellar contact forces. The magnitude of the inferosuperior patellar shear force increased significantly after patellar replacement with an oval, biconcave patellar component and increased further after replacement with an oval, domed patellar component. There were no significant changes in the mediolateral and anteroposterior contact force components after patellar replacement.