Explicit finite element modeling of wear within the patellofemoral joint in total knee replacement

Total knee replacement (TKR) surgery is one of the most successful and cost-effective procedures for treating knee injuries performed in orthopedics. However, the knee replacement revision surgery will probably be required after some years. Wear at the contact area between femoral metal component and the polyethylene inserts in TKR is recognized as one of the foremost causes of prosthesis failure and necessity of revision surgery. In the present study, focusing on the patellofemoral joint (PFJ), the wear at the contact area between the patellar and femoral components has been simulated employing the explicit finite element modeling. In this regard, common types of patellar component surface configurations, including dome, modified dome, offset dome, anatomic and mobile bearing, have been considered in this simulation. Besides, the effect of the curvature radius of the dome-shaped patellar component on wear behavior has been investigated. Finally, the maximum depth and volume of wear were calculated and compared among these different designs, using Archard's law. The results showed that more conforming articulation surfaces in the PFJ, increased the contact area, whereas reduced the contact stresses. Additionally, the decrement of contact stresses led to reduced wear volume of the patellar component. According to the results, the anatomical and mobile bearing designs indicated minimum wear depth due to their higher geometrical conformity with the femoral surface.