Vicente Sanchis-Alfonso, MD, PhD

Several papers published recently are warning us about the patellofemoral chondropathy progression after an open-wedge high tibial osteotomy (OWHTO), although the clinical consequences of those degenerative changes are still unclear. In fact, several studies have shown that the patellofemoral chondropathy progression after OWHTO did not affect clinical outcomes. Following this line of research, the objective of Lee and colleagues is to identify risk factors for patellofemoral degenerative progression after OWHTO and to investigate the effect of patellofemoral degeneration on the outcomes. These authors have evaluated the patellofemoral degenerative progression by means of a second-look arthroscopy and have observed that the progression of degenerative changes is correlated with an overcorrection of the mechanical axis in valgus. Furthermore, they have reported that this progression relates to poorer patient-reported outcomes.

I agree with the findings observed by Lee and colleagues. The results they present make perfect sense, since any variation of the normal skeletal alignment, in any of the three planes — coronal, sagittal and transverse — may increase the forces acting on the patellofemoral joint causing either ligament failure or cartilage failure and subsequently patellofemoral osteoarthritis. Anterior knee pain may result from these abnormal forces or their consequences. It is well known that skeletal malalignment in the frontal plane influences the progression of patellofemoral osteoarthritis. Therefore, when we perform an OWHTO we must avoid overcorrection. The first goal of a coronal plane osteotomy is to restore a neutral mechanical axis. If there is some articular deterioration medially, the new mechanical axis must fall near the lateral tibial spine, not beyond. If there is no medial articular damage, the new mechanical axis should be between the two tibial spines. The second goal would be to keep the joint line horizontal.