Osseous abnormalities and early osteoarthritis: the role of hip impingement.

The purpose of this study was to establish that anterior hip impingement, secondary to an anterior femoral offset deficiency from a pistol-grip deformity, was a common etiology of hip disorders. This impingement results in a spectrum of injury ranging from anterior hip pain, labral tears, damage to the acetabular articular cartilage and idiopathic arthritis. This was accomplished through three separate but closely related studies: (1) an arthroscopic labral tear study of 38 patients who had hip arthroscopy for a labral tear (2) a hip cheilectomy study of 10 patients who had a cheilectomy for anterior femoroacetabular impingement and (3) an idiopathic arthritis study of 200 consecutive patients having THA. In all three studies, a common etiology was identified. Repetitive anterior femoroacetabular impingement resulted in anterior groin pain, labral tears, chondral damage and eventually arthritis. This impingement was caused by a pistol-grip deformity of the proximal femur in 97% of the cases in the arthroscopic labral study and 100% of the cases in the idiopathic arthritis study. The identification of anterior hip impingement as a cause of labral tears and idiopathic arthritis may allow surgeons to correct it early in its natural history and delay or prevent end-stage arthritis.