FEMORAL ACETABULAR Impingement Syndrome

Hip impingement syndrome, also known as femoral acetabular impingement syndrome(FAIS), is a recently accepted condition that usually affects young and middle-aged adults. Pain is caused because two areas are contacting or impinging on each other resulting in pain. The femoral head rotates in the socket (acetabulum). During impingement, the neck of the femur contacts the lip of the hip socket.

It is characterized by hip pain felt mainly in the groin and can result in chronic pain and decreased range of motion. FAIS has been reported to be associated with progressive osteoarthritis of the hip.

Activities that cause problems with hip impingement are those that involve hip flexion, such as: sitting in a car, squatting, and bending during various athletic exercises. Pain can be minimal with straight and level walking.

The two basic mechanisms of FAI are cam impingement (most common in young athletic males) and pincer impingement (most common in middle-aged women). This classification is based on the type of anatomical variation contributing to the impingement process. Cam impingement is the result of abnormal shape of the femoral head-neck junction; while pincer impingement is the result of an abnormal shape of the hip socket (acetabulum). In this situation the socket "pinches" the neck during hip movement.

Femoroacetabular impingement or FAI is a condition of too much friction in the hip joint. Basically, the ball (femoral head) and socket (acetabulum) rub abnormally creating damage to the hip joint. This causes pain and eventual loss of motion of the hip. The damage can occur to the articular cartilage (smooth white surface of the ball or socket) or the labral cartilage (soft tissue bumper of the socket).

FAI is associated with cartilage damage, labral tears, early hip arthritis, hyperlaxity, sports hernias, and low back pain.

FAI is common in high level athletes, but also occurs in active individuals.


Most patients can be diagnosed with a history, physical exam, and plain x-ray films. A patient’s history will generally involve complaints of hip pain (front, side, or back) and loss of hip motion. The physical exam will generally confirm the patient’s history and eliminate other causes of hip pain. The plain x-ray films are used to determine the shape of the ball and socket as well as assess the amount of joint space in the hip. Less joint space is generally associated with more arthritis.

The treatment of FAIS is based on how much arthritis is present in the hip joint. If there is severe arthritis, with near bone-on-bone disease then a joint replacement would be indicated. However, a typical patient with FAIS has early arthritis and bone spurs (osteophytes) that are abnormally rubbing against each other causing labral tearing and injury to the cartilage. Surgery is most commonly performed to remove the bone spurs, sometimes referred to as the "hump" by contouring the bone on the neck ( procedure called a osteoplasty). Surgery also includes removing hyaline cartilage that is diseased (chondroplasty) and repair or removal of the injured labrum

Originally the surgery was described as a surgical dislocation of the hip. This procedure is commonly performed, however, with the better technology Dr. Matthys can perform the surgery using an arthroscope (hip arthroscopy). In some cases the procedure requires an arthrotomy. Here a small incision (3 inch) is made in the front of the hip to gain access to the labrum and hip joint. The hip can be evaluated and the labrum is repaired if possible. The excess bone is then removed under direct visualization. Surgery is performed under a general or regional anesthetic. Hospital stay is generally overnight, but can be performed as an outpatient.

Recovery time is dependent on the patient and the extent of bone removed. Some patients may be on protected weight bearing for 6 weeks if there has been extensive bone removal. In general recovery time is 3 to 6 months.

To learn more about FAIS and various conditions that can affect the hip please contact Dr. Matthys for a consultation at 701-241-9300 or 1-866-887-9300.