Zhang K, et al. - The associations between capsular thickness, hip range of motion, and demographic factors in patients with femoroacetabular impingement (FAI) were determined. A correlation between the increased anterior hip capsular thickness at the femoral head-neck and limitations in hip range of motion was noted in FAI. The pathologies, genders, and affected side could affect the strength of this relationship. On clinical examination, pathologic thickening of the hip capsule could contribute to restricted hip mobility, and elucidation of this relationship could provide guidance into capsular management during hip arthroscopy.