Femoroacetabular Impingement

Femoroacetabular impingement (FAI) is a condition where there is abnormal contact betweek the femur (ball) and the acetabulum (socket).  This can be a result of an irregularly shaped ball or socket. The femoral head and acetabulum abut 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 .

Femoroacetabular impingement generally occurs as two forms: Cam (from prominence on the femoral (ball) side and Pincer (from prominence of the acetabular (socket) side.  

CAM Impingement: The Cam form of impingement occurs when the femoral head is not perfectly round.  This lack of roundness and excess bone causes abnormal contact between the surfaces.

PINCER Impingement: The Pincer form of impingement occurs when the rim of the acetabulum (socket) is too prominent / 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 (retroversion) causing abnormal impact between the femoral head and the rim of the acetabulum.

Many diagnoses of FAI include a combination of the Cam and Pincer forms.

Symptoms of FAI

Symptoms of femoroacetabular impingement can include the following:

  • Groin pain associated with hip activity
  • Complaints of pain in the front (or less commonly the side) 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 (in cars, airplanes, etc) or walking
  • Difficulty walking uphill or downhill
  • Restricted hip movement
  • Low back pain can sometimes be associated but is not a direct result of FAI.

Risk Factors

Although the shape of the bony structures of the hip is largely determined by the time a person reaches adolescence, not all patients with irregular bony anatomy will develop symptoms. Risk factors for developing symptoms of femoroacetabular impingement may include the following:

  • Athletes such as football players, weight lifters, and hockey players
  • Heavy labourers
  • Repetitive hip flexion
  • Congenital / Childhood hip disorders
  • Anatomical abnormalities of the femoral head or angle of the hip
  • Trauma to the hip

Diagnosis

Hip conditions should be evaluated by an orthopaedic hip surgeon for proper diagnosis and treatment.  Dr. Dumont specializes in hip injuries, and will perform a thorough assessment to determine the cause of your pain and propose appropriate treatment options.  The evaluation will include:

  • Medical History - the description of symptoms often offers valuable clues as to the diagnosis.
  • Physical Examination - certain tests and maneuvers can confirm the diagnosis.
  • Diagnostic studies including X-rays, MRI scans and CT Scan.

Treatment Options

Conservative treatment options refer to management of the problem without surgery. Nonsurgical management of FAI will not change the underlying irregular bony shape of the hip or the abnormal biomechanics of the hip,  but may offer pain relief and improved mobility. It is often considered a valuable first line of treatment.

Conservative treatment measures

  • Rest
  • Activity Modification and Limitations
  • Anti-inflammatory Medications
  • Physical Therapy
  • Injection of steroid and analgesic into the hip joint

Surgical treatment

Hip arthroscopy to correct the irregular shape of the hip and reducing bony impingement, and repair of associated injuries to the labrum and cartilage, is indicated when conservative treatment measures fail to provide relief to the patient. Hip arthroscopy is a surgical procedure in which an arthroscope is inserted into the hip joint to assess and repair damage to the hip. Hip arthroscopy is performed in a hospital operating room under general or regional anesthesia depending on you and your surgeon’s preference.

This surgery is usually performed as day surgery or outpatient surgery, enabling the patient to go home the same day. The arthroscope used in hip arthroscopy is a small fiber-optic viewing instrument made up of a tiny lens, light source and video camera. The surgical instruments used in arthroscopic surgery are very small (only 3 or 4 mm in diameter), but appear much larger when viewed through an arthroscope.

The television camera attached to the arthroscope displays the image of the joint on a television screen, allowing the surgeon to look throughout the hip joint. The surgeon can then determine the amount or type of injury, and then repair or correct the problem as necessary.

In arthroscopic repair of FAI, your surgeon may perform the following procedures:

  • Chondroplasty-: This refers to surgery to repair torn cartilage or a torn labrum. Sutures are used to reattach the torn labrum or cartilage.
  • Microfracture-: This involves drilling holes into bare bone where cartilage is missing to promote the formation of new cartilage.
  • Labral/Cartilage debridement-: This type of debridement refers to cutting out and removing pieces of torn or frayed labrum or cartilage.
  • FAI decompression-: This involves removing any pressure areas, such as bony bumps, causing the impingement.
  • Osteoplasty-: This refers to a surgical procedure to modify or alter the shape of a bone.

For FAI surgery, your surgeon will use a special instrument called a shaver to cut away or debride any frayed cartilage. If the labrum is torn, your surgeon will use sutures to preserve and reattach the labrum.

Any bony bumps present contributing to the impingement will also be shaved away and smoothed. Your surgeon may drill holes in bone that has no cartilage covering it. This technique is called microfracture and stimulates the formation of new cartilage.

Once your surgeon is satisfied with the results, the instruments and arthroscope are removed from the portals. The portals (incisions) are then closed by suturing or by tape.

Arthroscopic repair of FAI, offers several advantages to the patients and they include:

  • Smaller incisions
  • Minimal soft tissue trauma
  • Less pain
  • Faster healing time
  • Lower infection rate
  • Less scarring
  • Earlier mobilization
  • Usually performed as outpatient day surgery

As with any major surgery there are potential risks involved. The decision to proceed with the surgery is made because the advantages of surgery outweigh the potential disadvantages. It is important that you are informed of these risks before the surgery takes place. Complications can be medical (general) or specific to hip arthroscopy surgery.

Medical complications include those of the anesthetic and your general well being. Almost any medical condition can occur so this list is not complete. Complications include:

  • Allergic reactions to medications
  • Blood loss requiring transfusion with its low risk of disease transmission
  • Heart attacks, strokes, kidney failure, pneumonia, bladder infections
  • Complications from nerve blocks such as infection or nerve damage
  • Serious medical problems can lead to ongoing health concerns, prolonged hospitalization, or occasionally death

Complications are rare after hip arthroscopy surgery, but unexpected events can follow any operation. Please talk to your surgeon for more information on femoroacetabular impingement.

  • American Orthopaedic Society for Sports Medicine
  • The Arthroscopy Association of North America
  •  American Academy of Orthopaedic Surgeons
  • International Society for Hip Arthroscopy