Reduced hip adduction is associated with improved function after movement-pattern training in young people with chronic hip joint pain

STUDY DESIGN: Ancillary analysis, time-controlled randomized clinical trial. BACKGROUND: Movement-pattern training (MPT) has been shown to improve function among patients with chronic hip joint pain (CHJP). OBJECTIVE: To determine the association among treatment outcomes and mechanical factors associated with CHJP. METHODS: Twenty-eight patients with CHJP, 18 to 40 years of age, participated in MPT, either immediately after assessment or after a waitlist period. Movement-pattern training included task-specific training to reduce hip adduction motion during functional tasks and hip muscle strengthening. Hip-specific function was assessed using the Modified Harris Hip Score (MHHS) and Hip disability and Osteoarthritis Outcome Score (HOOS). Three-dimensional kinematic data were used to quantify hip adduction motion, dynamometry to quantify abductor strength, and magnetic resonance imaging to measure femoral head sphericity using the alpha angle. Paired t tests assessed change from pretreatment to posttreatment. Spearman correlations assessed associations. RESULTS: There was significant improvement in MHHS and HOOS scores (P≤.02), adduction motion (P = .045), and abductor strength (P = .01) from pretreatment to posttreatment. Reduction in hip adduction motion (r = -0.67, P<.01) and lower body mass index (r = -0.38, P = .049) correlated with MHHS improvement. Alpha angle and abductor strength change were not correlated with change in MHHS or HOOS scores. CONCLUSION: After MPT, patients reported improvements in pain and function that were associated with their ability to reduce hip adduction motion during functional tasks.