To investigate the responsiveness to exercise therapy of patients with femoroacetabular impingement syndrome (FAIS), and to investigate differences in hip function, strength, and morphology between responders versus nonresponders.
Patients with FAIS underwent 12 weeks of semi-standardized and progressive exercise therapy. A good therapy outcome (responders) versus a poor therapy outcome (nonresponders) was determined at week 18 with the Global Treatment Outcome questionnaire for hip pain. Hip function was evaluated using the Hip Outcome Score (HOS) activities of daily living (ADL) and Sport at baseline, and at weeks 6, 12, and 18. Hip muscle strength and dynamic pelvic control were evaluated using dynamometry and video analysis, respectively, at baseline, week 12, and week 18. Hip morphology was evaluated with imaging at baseline.
Thirty-one patients (mean age 24 years) were included. Sixteen patients (52%) were responsive and 15 patients (48%) were not responsive to exercise therapy. Only responders improved HOS ADL and HOS Sport by 10 points (95% confidence interval [95% CI] 7, 14; P < 0.001) and by 20 points (95% CI 15, 25; P < 0.001), respectively, and hip abductor strength by 0.27 Nm/kg (95% CI 0.18, 0.36; P < 0.001). The prevalence of patients showing good dynamic pelvic control only increased in responders (44%; P = 0.029). The prevalence of severe cam morphology was higher in nonresponders than in responders (40% versus 6%; P = 0.037).
Half of patients with FAIS benefit from exercise therapy in the short term. Responsiveness to hip abductor strength and dynamic pelvic control improvements is associated with a good therapy outcome, whereas the presence of severe cam morphology is associated with a poor therapy outcome.