How does normal flexion patellofemoral contact area change before and after deep knee flexion?

For active patients with total knee replacements (TKR) and cultures in which kneeling occurs frequently, patellofemoral stresses are an important consideration. The impact of deep knee bending activities on normal flexion patellofemoral stresses is not well understood. The goal of this study was to investigate the influence of deep knee bending on normal flexion contact area and stress on an all-polyethylene patellar component used in TKR. Contact area and stress values were measured with the use of TekScan™. It was found that for knee flexion angles 80°, 100°, and 120° the contact area increased by a minimum of 10% after a simulated 20 years of deep knee bending. Similarly, stresses in the components decreased.