Three-dimensional tibiofemoral kinematics during deep flexion kneeling in a mobile-bearing total knee arthroplasty.

Achieving very deep flexion after total knee arthroplasty is an important goal of most patients in Japan, Asia, and the Middle East because of floor-sitting lifestyles. Numerous knee arthroplasty designs have been introduced to permit high flexion. We performed an in vivo radiographic analysis of tibiofemoral motions during weight-bearing kneeling in one high-flexion knee arthroplasty design. Twenty knees implanted with a posterior-stabilized rotating-platform knee arthroplasty flexed an average of 126 degrees. The femoral condyles translated posteriorly from extension to maximum flexion. Total posterior condylar translations averaged 11.6 and 4.7 mm for the lateral and medial condyles, respectively. Tibial internal rotation in 19 knees averaged 9 degrees from extension to maximum flexion. Knees implanted with a posterior-stabilized, rotating-platform knee arthroplasty show deep flexion knee kinematics consistent with the implant design intent.