Editorial Commentary: Patellofemoral Instability Results in Osteoarthritis, and Nonanatomic Surgery and Surgical Over-constraint May Also Cause Osteoarthritis.

When we are looking at the stars, we are in fact looking back in time. This is because it takes years for the light from the stars to reach us. In similar fashion, when we are evaluating data on osteoarthritis after patellofemoral surgery, we need to consider what kind of procedure was performed. Furthermore, it is extremely important to answer the question of whether the patellofemoral instability itself or the surgical procedure is causing the arthritis. Recent evidence suggests that recurrent patellofemoral instability is causing cartilage degeneration and stopping this process via surgical restoration of the anatomy and biomechanics of the patellofemoral joint may significantly reduce the risk of osteoarthritis. Shear loading of the cartilage can be detrimental. An instability event elicits inflammatory markers that are shown to induce arthritis. On the other hand, there is the argument that over-constraint may lead to arthritis owing to an increase in cartilage loading. Another argument is that surgery may not fully restore the patellofemoral anatomy. Appropriate patient selection and continuous evolution of our surgical procedures are key elements toward successful management of patellofemoral instability.