Femoroacetabular impingemennt is also known as hip impingement and sometimes called FAI for short.
Femoroacetabular impingement (FAI) is a condition where there is too much friction 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 labral tissue (the lining of the edge of the socket) during normal movement of the hip. The articular cartilage or labral tissue can fray or tear after repeated friction. Over time, more cartilage and labrum is damaged until eventually the femur bone and acetabulum bone impact on one other. Bone on bone friction is commonly referred to as Osteoarthritis.
FAI impingement generally occurs as two forms: Cam and Pincer. Most patients have elements of both types of impingement.
CAM Impingement: The Cam form of impingement is when the femoral head and neck are not perfectly round, most commonly due to excess bone that has formed. This lack of roundness and excess bone causes abnormal contact between the surfaces.
PINCER Impingement: The Pincer form of impingement is when the socket or acetabulum rim has overgrown and is too deep. It covers too much of the femoral head resulting in the labral cartilage being pinched. The Pincer form of impingement may also be caused when the hip socket is abnormally angled backwards causing abnormal impact between the femoral head and the rim of the acetabulum.
Symptoms of femoroacetabular impingement may include:
Groin pain associated with hip activity
Front, side, buttock pain location
Pain can be dull, achy, or sharp and knife-like
Mechanical symptoms may include locking, catching, giving way
Pain often radiates to front or inner thigh but does not typically go below the knee
Pain is worse with sitting, squatting, walking up or downhill
Range of motion may decrease
Treatment options include conservative (non-surgical) and surgical:
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.
Activity modification and limitations
Injection of steroid
Injection of biologics: platelet rich plasma or stem cell
Hip arthroscopy (minimally invasive surgery) to repair femoroacetabular impingement is indicated when conservative treatment measures fail to provide relief to the patient. This surgery addresses the bony impingement by removing the collision between the bones. It also repairs the labrum and addresses any cartilage damage.