Hip impingement also known as Femoral Acetabular Impingement (FAI) is the clinical term for abnormal contact between two joint partners (Hendry et al., 2013). It may occur within the joints of the human body when the biomechanic of the joint is disturbed through biomechanical disbalance, injury/trauma or simply the ageing process of the structures.
The hip is a ball and socket joint; the ball is the femoral head, the top of the thigh bone, which is connected through a tight bursa and ligaments into the inner friction of the socket, acetabulum. This over-coverage typically exists along the front-top rim of the socket (acetabulum) and results in the labral cartilage being “pinched” between the rim of the socket and the thigh bone.
Femoral acetabular impingement (FAI) occurs when the hip which is made up of a ball (femoral head) and socket (acetabulum) rubs abnormally creating damage to the hip joint. FAI generally occurs as two forms: Cam and Pincer.
The Cam form occurs when the ball of the joint is not perfectly round. This loss of roundness contributes to abnormal contact between the head and socket. The Pincer form occurs when the socket has too much coverage of the ball.
FAI is associated with cartilage damage, labral tears, early hip arthritis, hyper-laxity, sports hernias, and low back pain.
Treatment includes strengthening of the pelvic girdle, manual therapy to ease the pain and regain restricted movement; in severe cases hip arthroscopy is necessary.
Hendry D. et al., 2013, Femoral Acetabular Impingement, Seminars in Roentgenology, 48(2), pp: 158-166