Which factors predict outcome in the nonoperative treatment of patellofemoral pain syndrome? A prospective follow-up study.

This study determined prospectively the outcome-predictive role of 22 background variables in the nonoperative treatment of chronic patellofemoral pain syndrome. The general variables registered age, sex, body composition, athletic activity, and duration of symptoms. The remaining variables measured clinically and radiologically the biomechanical malalignments in the lower extremities. In 49 consecutive patients, these variables were measured at the entry of the 6-wk treatment protocol (rest, NSAIDs, and intense isometric quadriceps exercises), and the outcome was determined at 6 wk and 6 months using improvements in the 100-mm Visual Analog Scale and the Lysholm and Tegner knee scores as outcome criteria. A multiple stepwise regression analysis indicated that age was the only factor which significantly (P < 0.05 to 0.005) but not very strongly associated with the outcome: the younger the patient the better the outcome (r = -0.34 to -0.41 at 6 wk, and -0.25 to -0.41 at 6 months). Inclusion of any of the other predictive variables in the analytic model did not significantly improve the prediction. This result suggests that quadriceps rehabilitation is worth trying for every patient (70% experienced complete recovery) regardless patient's age, sex, body composition, athletic level, duration of symptoms, or biomechanical malalignments in the lower extremities.