Femoro-acetabular impingement (FAI) occurs where there is abnormal contact between the femoral head (ball) and the edge of the acetabulum (socket). This abnormal contact can lead to damage to the labrum of the hip and the articular cartilage (joint lining) in the acetabulum. Damage to the labrum and/or surrounding articular cartilage can cause pain.
FAI usually occurs if there is an abnormality of the shape of the femoral head (Cam deformity) or of the acetabulum (pincer) or both (mixed). The abnormal shape in the ball or socket may lead to abnormal contact during hip movements, in particular sporting type movements. For example, kicking sports, dancing and martial arts. The damage is usually an accumulation of micro trauma from repetitive impaction (impingement).
FAI may occur in all age groups, but presents more frequently in young athletic adults and is recognised as a predisposing factor to early osteoarthritis/degeneration of the hip. It is increasingly thought that early surgical intervention for acetabular impingement will alleviate pain and help minimise the development of osteoarthritis of the involved hip. Hip arthroscopy is used to treat any damage to the articular cartilage or labrum as well as to reshape any bone abnormalities in the ball or socket.