Femoroacetabular impingement (FAI) is a condition where there is a kinematic dysfunction in the hip joint from bony irregularities causing pain and decreased range of hip motion. The femoral head and acetabulum rub against each other creating damage and pain to the hip joint. The damage can occur to the articular cartilage (the smooth white surface of the ball or socket) or the labrum (the flexible bumper around the edge of the socket) during movement of the hip. The articular cartilage or labrum can fray or tear after repeated impingement. Over time, more cartilage and labrum is lost until eventually the femur and acetabulum impact directly on one other. Bone on bone degenerative joint disease is also known as Osteoarthritis.
FAI generally occurs as two types: Cam and Pincer.
CAM Impingement: The Cam type of impingement occurs when the femoral head and neck are not perfectly round, most commonly due to excess bone that has formed. The change in geometry due to excess bone causes abnormal contact between the surfaces.
PINCER Impingement: The Pincer type of impingement occurs when the acetabular rim has overgrown and is too deep. It covers too much of the femoral head resulting in the labral cartilage being pinched. Pincer impingement may also be caused when the hip socket is angled backwards more than usual causing abnormal impact between the femoral head and the rim of the acetabulum.
Most diagnoses of FAI include a combination of the Cam and Pincer type impingement.
Symptoms of FAI
Symptoms of femoroacetabular impingement can include the following:
- Groin pain associated with hip range of motion
- Complaints of pain in the front, side or back of the hip
- Pain may be described as a dull ache or sharp pain
- Patients may complain of a locking, clicking, or catching sensation in the hip
- Pain often occurs to the inner hip or groin area after prolonged sitting or walking
- Difficulty walking uphill
- Restricted hip movement
- Low back pain
- Pain in the buttocks or outer thigh area
Risk factors for developing femoroacetabular impingement may include the following:
- Athletes such as football players, weight lifters, and hockey players
- Heavy laborers
- Repetitive hip flexion
- Congenital hip dislocation
- Anatomical abnormalities of the femoral head or angle of the hip
- Legg-Calves-Perthes disease: a form of arthritis in children where blood supply to bone is impaired causing bone breakdown.
- Trauma to the hip
- Inflammatory arthritis
Hip conditions should be evaluated by an orthopedic hip surgeon for appropriate diagnosis and treatment. Workup includes:
- Focused History
- Physical Examination
- Diagnostic studies such as X-rays, MRI or CT Scan
Conservative treatment options refer to management of the problem without surgery. Nonsurgical management of FAI will probably not change the underlying abnormal biomechanics of the hip causing the FAI but may offer pain relief and improved mobility.
Conservative treatment measures
- Activity Modification and Limitations
- Anti-inflammatory Medications
- Physical Therapy
- Injection of steroid and analgesic into the hip joint
- Hip arthroscopy to repair femoroacetabular impingement is indicated when conservative treatment measures fail to provide relief to the patient.