Females with patellofemoral pain syndrome have weak hip muscles: a systematic review.

QUESTION Do females with patellofemoral pain syndrome have decreased hip muscle strength compared with the unaffected side and with healthy controls? DESIGN A systematic review of observational studies published up to January 2008. PARTICIPANTS Females with patellofemoral pain syndrome and healthy controls. OUTCOME MEASURES Strength for at least one hip muscle group had to be included in the study. Hip muscle strength was recorded as force or torque. RESULTS Five cross-sectional studies with a mean Newcastle-Ottawa Assessment Scale score of 6 out of 9 met the inclusion criteria. Strong evidence was found for a deficit in hip external rotation, abduction and extension strength, moderate evidence for a deficit in hip flexion and internal rotation strength, and no evidence for a deficit in hip adduction strength compared with healthy controls. Moderate evidence was found for a decrease in hip external rotation and abduction strength but no evidence for a decrease in hip extension, flexion, adduction and internal rotation strength compared with the unaffected side. CONCLUSION Females with patellofemoral pain syndrome demonstrate a decrease in abduction, external rotation and extension strength of the affected side compared with healthy controls.