Femoro-Acetabular Impingement (FAI)

Includes Labral Tears, CAM lesions, Some types of Dysplasia

Overview:  This condition is related to a condition where the femoral head, acetabulum and /or both are abnormally shaped.  The abnormal shape can cause excessive friction during range of motion of the ball and socket joint causing damage to the cartilage.  It affects both articular-smooth surface of femoral head (ball) and acetabulum (socket) and/or the labral cartilage (shock absorber lining of joint).  It can lead to arthritis, labral tears and decreased range of motion.

  • Two types of Femoroacetabular Impingement:
    • CAM impingement-this type of impingement got its name from the irregular shape of femoral head (ball) and femoral neck.   Because they are not perfectly aligned, motions such as deep flexion and internal rotation can cause erosion of cartilage off ends of bone or tearing of the labrum.  This can result in arthritis of the hip joint over time.
    • PINCER impingement:  This is characterized by excess bone on acetabulum.   This type of impingement got its name from the pinching (pincer) of the labrum between the excess bone of the acetabulum.  This can result in labral tears and eventually lead arthritis of hip joint.
    • COMBINED:  patients can present with both type of lesions. 


  • Deep groin pain with certain activities radiating in the front pocket
  • It may mimic a ‘pulled groin’
  • Catching, locking, grinding sensation in hip or groin
  • Pinching type pain when flexing hip past 90 degrees
  • Pain with prolonged sitting
  • Occasional pain radiating to thigh, knee or buttock
  • Weight bearing pain (if arthritis is present)


  • X-ray (2 dimensional view of bone)-  this is a non-invasive tool used to evaluate for arthritis
  • MR Arthrogram - this involves injection of contrast into joint to evaluate soft tissue, cartilage defects and labral tears.   This is more sensitive than standard MRI for evaluation.
  • CT SCAN – not routinely ordered, but can offer a more in-depth view of bone, not for soft tissue evaluation


  • Non-operative (after diagnosis is confirmed)
    • Weight loss, if over ideal body weight
    • Assistive Device in Contralateral (opposite hand)
    • Non-Steroidal Anti-inflammatories
    • Injections - these injections are used for both diagnostic and therapeutic modality.  They may be done at time of MR arthrogram.  Typical injection has anesthetic and steroid.  They may provide pain relief for three months.  These are typically done in radiology under fluoroscopic or ultrasound assistance.
  • Operative (depends to large degree on the type and amount of deformity and the presence of arthritic change
    • Hip arthroscopy (SCOPE) - This is performed through small incisions in skin to allow a camera to visual the structures within the hip. This can address the labrum, the femoral head deformity and or an abnormally shaped acetabulum. This is typically performed by a surgeon who specializes in sports injuries and or has formal training in hip arthroscopy. Patients are candidates for hip scopes with and without labral tears WITHOUT arthritis. The labrum can either debrided (trimmed) or repaired. This is determined by the quality of the labrum and size of tear along with the type of deformity.
    • Open surgical dislocation - This is a procedure where the blood supply to the hip is preserved while dislocating the ball from the socket. It allows increased exposure to correct deformities of the ball or socket. It is performed by surgeons with advanced training in surgical dislocation for a variety of types of FAI with the absence of advanced arthritis.
    • Acetabuloplasty- (trimming of the excess bone on labrum-PINCER type lesion) this is an operative procedure that involves removal with a device called a burr. It can be performed with a scope or open.
    • Osteochondroplasty-(trimming of excess bone on femoral neck-CAM type lesion) this is an operative procedure that involves removing excess bone on femoral neck to re-establish a round femoral head (ball). Patients may be limited weight bearing to protect against femoral neck fractures post op. This can be performed either through a scope or open.
    • Total hip replacement- Operative procedure which removes femoral head, neck and damaged cartilage in acetabulum. The bone is replaced with metal and plastic bearing surfaces. This procedure is offered when the femoro-acetabular impingement has led to extensive cartilage damage on femoral head (ball) and acetabulum (pelvis). This is an open procedure with an incision, not performed under arthroscopy (scope). This is the definitive treatment for FAI and or labral tears and or hip dysplasia (shallow socket) where arthritis has occurred and is performed by a surgeon specializing in knee and/or hip replacement. It can be either the first choice procedure or a salvage procedure when a scope or open dislocation has failed. It has durable results at and beyond twenty years and is being performed in young patient through less invasive techniques allowing earlier recovery.