Extra-articular hip impingement: a review of the literature.

Hip and groin pain is a common clinical problem. Multiple causes can generate hip or groin pain, often sharing clinical and demographic characteristics. Diagnostic imaging tests play an important role in the etiological diagnosis. New forms of extra-articular hip impingement have recently been recognized as a cause of hip pain and limited function especially in young active patients. These conditions include ischiofemoral impingement, anterior inferior iliac spine and subspine impingement, iliopsoas impingement and greater trochanteric-pelvic impingement. In general, they are caused by a mechanical conflict with an abnormal or excessive contact between the proximal femur and pelvis and/or soft tissue between them. In this manuscript we review the physiopathology, clinical presentation, the most common radiologic findings and treatment of these forms of extra-articular hip impingement.