Contact Stress Analysis of the Conforming Post-Cam Mechanism in Posterior-Stabilized Total Knee Arthroplasty

The present study evaluated the effects of extent of conformity of post-cam design on contact area and stress at post-cam mechanism using 4 different posterior-stabilized prostheses. TRAC and Alpina with full-conformed post-cams exhibited the largest contact area at 90° and 120°. PFC sigma RPF with partial conformed post-cam had the largest contact area at 150°. Scorpio NRG with less conformed post-cam had smaller contact area than the others. Lifting of femoral component decreased contact area and increased contact stress of TRAC and Alpina. Recent modifications of post-cam design have increased contact area, contributing to lower contact stress. None of these prostheses exhibited constant low contact stress throughout flexion. Further modifications of post-cam mechanism are necessary to provide lower contact stress throughout deep knee flexion.