Pre-operative patellofemoral degenerative changes do not affect the outcome after medial Oxford unicompartmental knee replacement: a report from an independent centre.

There has been debate about the role of unicompartmental knee replacement in the presence of radiologically identifiable degenerative changes of the patellofemoral joint. We studied 195 knees in 163 patients in whom an Oxford unicompartmental knee replacement had been performed for medial osteoarthritis between January 2004 and July 2007. The mean age of the patients was 66 years (51 to 93). The degree of degenerative change of the patellofemoral joint was assessed using Jones' criteria. Functional outcome was assessed at a mean of 3.4 years (2 to 7) post-operatively, using the Oxford knee score and the Short-form 12 score. Degenerative changes of the patellofemoral joint were seen pre-operatively in 125 knees (64%) on the skyline radiographs. There was no statistically significant difference in the Oxford knee or Short-form 12 scores between those patients who had patellofemoral osteoarthritis pre-operatively and those who did not (p = 0.22 and 0.54, respectively). These results support the opinion expressed at the designer's hospital that degenerative changes of the patellofemoral joint in isolation should not be considered to be a contraindication to medial Oxford unicompartmental knee replacement.