Altered Hip Biomechanics and Compensatory Mechanisms in Femoroacetabular Impingement Patients

Cam-type femoroacetabular impingement (FAI) is characterized by abnormal femoral head morphology, disrupting hip joint biomechanics and leading to pain, joint degeneration, and functional impairments. This study aimed to investigate the biomechanical adaptations and compensatory mechanisms employed by individuals with unilateral cam FAI during walking, squatting, and single-leg tasks. Biomechanical analysis revealed significant deficits in the symptomatic hips, including reduced hip extension and abduction moments, altered pelvic tilt, and increased trunk lean during squatting. Contralateral hips demonstrated compensatory increases in abduction and internal rotation moments, stabilizing the pelvis but exposing them to overuse risks. Balance and postural control deficits were identified in both hips, with significant reductions in Star Excursion Balance Test reach distances. These findings highlight the bilateral impact of cam FAI and the critical role of compensatory mechanisms in maintaining dynamic stability. Rehabilitation strategies must address both symptomatic and asymptomatic hips to optimize function and reduce long-term risks.