Vicente Sanchis-Alfonso, MD, PhD

The authors analyze the results of a second-generation patellofemoral arthroplasty implant, which has as a specific characteristic an asymmetrical trochlea with a long, steep lateral slope. It is an observational retrospective study with a small cohort of patients and only mid-term outcomes (mean follow-up 64 months [30 to 119 months]). Therefore, we cannot draw too many conclusions regarding the benefits of this implant. We would need to do a good quality clinical trial with long-term outcomes to evaluate the results and advantages of this implant. In my opinion, the most relevant aspect of this study is the fact that five knees (12%) were revised to total knee replacement because of pain and disability due to the progression to tibiofemoral osteoarthritis. The authors admit that three of these five cases required an early revision to TKR because of degenerative changes at the time of surgery in the tibiofemoral joint, specifically in weight-bearing areas. This means that patient selection was incorrect. I believe the most important element, and also the most difficult one, in surgery, and specifically in patellofemoral surgery, is the indication of a specific surgical technique. The ideal indication for patellofemoral arthroplasty is post-traumatic, isolated, severe patellofemoral OA and severe, isolated patellofemoral OA in a patient with severe trochlear dysplasia and a history of patellar dislocation. In these cases, we are bound to obtain the best outcome. However, these cases represent only 42% of all the cases of patellofemoral OA.