Current management of femoro-acetabular impingement

Summary Femoro-acetabular impingement (FAI) is a common cause of hip pain in young adults. The condition can result in labral tears, articular cartilage lesions and eventual osteoarthritis of the hip. FAI results from an abnormal bony shape of the femoral head / neck or the acetabular rim or both, which causes contact (impingement) between the neck and acetabular rim during movement of the hip joint. Two different mechanisms are described, although a combination of the two mechanisms is frequent. Cam impingement is caused by an abnormality of the femoral head and neck; principally a reduction in offset between the head and the neck. Pincer impingement is caused by an abnormality on the acetabular side, with either excessive retroversion of the acetabulum or an unduly prominent anterior wall. Either problem is associated with the development of chondral lesions (especially in the acetabulum) and labral pathology. Patients with FAI usually present with deep groin pain exacerbated by hip flexion. X-rays typically show an anterior impingement bump on the anterior femoral neck on a horizontal beam lateral, abnormalities of head/neck offset or an excessively prominent anterior acetabular wall. Surgery is the treatment of choice and this involves open or arthroscopic bony resection to improve femoral head-neck clearance with either resection or refixation of the damaged labrum. Both the femoral head/neck junction and the acetabular rim may require bony resection. Such surgery yields good symptomatic relief, but whether the surgery prevents the development of osteoarthritis in the hip in the long term is currently unknown.