Femoroacetabular impingement …What is it?

Femoroacetabular impingement is a condition of too much friction in the hip joint. This is a result of the femoral head sitting and or moving incorrectly in the acetabulum.

The ball or femoral head and socket (acetabulum) are poorly positioned and rub abnormally creating damage to the hip joint.  The damage can occur to the articular cartilage as well (the smooth white surface of the ball or socket) or the labral cartilage (soft tissue bumper of the socket).The poor positioning of the femoral head in the acetabulum can be due to the following factors: a poorly formed humeral head which could be the result of genetics (or from birth), the result of excessive wear, or the result of medications (e.g. cortisone can cause a breakdown of bone …causing osteoporosis), excessively large socket, excessively thickened femoral neck and the acetabularlabrum overhangs the acetabulum and contacts the femoral neck limiting range of movement which in turn can disrupt normal movement patterns. This can be the result of excessive over loading especially through the years of puberty. The situation may also occur in elite junior sport stars such as tennis players. Often FAI can show no symptoms and may appear simply as a click. Some people may experience pain but not in all cases. FAI generally occurs as two forms: Cam and Pincer.  The cam form is a Dutch term meaning COG and describes the femoral head and neck relationship as aspherical or incorrectly formed or shape change.  This loss of shape or roundness contributes to abnormal contact between the head and socket.  The Pincer form is based on a French word meaning “to pinch” which describes the situation where the socket or acetabulum has too much coverage of the ball or femoral head.                                            

This (over) coverage exists along the front top rim of the socket (acetabulum) and results in the labral cartilage being “pinched” between the rim of the socket and the anterior femoral head neck at the junction.  The Pincer form of the impingement is typically secondary to “retroversion”, a turning back of the socket, “profunda”, a socket that is too deep, or “protrusio”, a situation where the femoral head extends into the pelvis.  Most of the time, the Cam and Pincer forms exist together which results in a mixed impingement where both are at fault. This injury is associated with labral tears, cartilage damage, osteo, hyper laxity and can produce lower back pain in some sufferers. The condition occurs often in top level athletes and very active people.

Treatment: (source: http://www.mdguidelines.com/femoral-acetabular-impingement)

If symptoms of FAI are intermittent or mild, conservative treatment is indicated using nonsteroidal anti-inflammatory drugs (NSAIDs), daily activity modification to reduce compression and end-range movements of the hip, and cessation of sports or other aggravating factors that increase hip pain.

Because FAI is a mechanical impingement of the hip joint, individuals with chronic, constant, symptomatic FAI may need to be treated surgically to scrape away bony lesions around the joint, resect impinged tissues, and enhance movement of the restricted joint. Surgery may be performed arthroscopically (minimally invasive surgery) or through an open incision. Arthroscopic resection may be performed as a same-day procedure, with hip range of motion exercises initiated within the first 4 hours after surgery to prevent scar tissue formation and adhesions. Typically, the individual is instructed to use a continuous passive motion (CPM) machine beginning between the angles of 30 degrees to 70 degrees of hip flexion, and progressing to 0 degrees to 90 degrees of flexion by the second week (Tyler). Physical therapy is typically begun within the first postoperative week.

Following arthroscopic surgery, weight bearing may be limited to 5kgs of pressure with a flat-foot gait pattern on the operated limb for the first 2 to 4 weeks (Philippon; Tyler). The individual also may be instructed to wear a modified brace or wrap around the feet at night to restrict hip internal and external rotation for the first 10 to 14 days (Philippon; Tyler). After open surgery (surgical hip dislocation with débridement or peri-acetabular osteotomy, in which the location of the hip socket is moved), weight bearing may be limited for the first 4 to 6 weeks, with full return to activity at 3 months (Shah).

Individuals with severe osteoarthritis of the hip in conjunction with FAI may require a total hip arthroplasty.


The efficacy of conservative treatment for FAI is unknown (Lewis). In individuals without significant hip osteoarthritis before surgery for FAI, hip pain is reduced and return to normal activities and sports participation is generally good over the short-term. Arthroscopic surgery for labral repair and débridement is successful in 67% to 100% of individuals (Bedi). Open surgery for labral débridement and osteoplasty is successful in 65% to 85% of individuals (Bedi). Overall, surgical techniques for FAI ranging from arthroscopic to open approaches results in improved function and pain relief in 68% to 96% of individuals over a 2- to 5-year follow-up period (Clohisy). However, long-term resolution of hip symptoms after a surgical approach, and whether hip osteoarthritis is prevented by surgical intervention, is not known. Across approaches, up to 26% of cases are converted to total hip arthroplasty (Clohisy).


For conservative management of FAI, the focus of rehabilitation is to reduce direct weight-bearing forces on the hip, strengthen surrounding hip and trunk musculature to enable a normal gait pattern, and to educate individuals to modify functional activities in order to reduce pressure at the hip joint and limit excessive range of motion, particularly in hip extension beyond neutral (Lewis). Gait training with an assistive device (e.g., cane, crutch) may be necessary to temporarily reduce the amount of loading on the affected hip. The individual is instructed in a comprehensive home exercise program that includes joint protection strategies and is taught that strengthening exercises should be performed within pain free ranges of motion.

Following hip arthroscopy for FAI, the goal of rehabilitation is to restore full hip range of motion and strength. Postoperative rehabilitation is guided by the treating physician, with weight bearing restrictions as indicated to allow healing to occur without re-injury. Modalities such as ice may be used for pain and swelling. Hip flexibility exercises are initiated within pain free range of motion and in accordance with the surgeon’s protocol for hip internal and external rotation restrictions postoperatively. Strengthening exercises are introduced at first isometrically with the operated limb in a neutral position, and advanced as tolerated and with regard to weight-bearing status. Strengthening exercises should include core stabilization activities to improve trunk strength in addition to hip muscle strength (Tyler).

Physical therapy treatment also may include pool exercises after wound closure and stationary bicycling, although recumbent bicycling is avoided to reduce end-range hip flexion (Tyler). Gait training may be necessary to restore normal movement patterns as the individual transitions from using an assistive device to ambulating independently. Balance and proprioception exercises are introduced as hip strength returns, and as weight bearing status allows.

A home program will be taught to complement supervised rehabilitation and to be continued after the completion of physical therapy.


FAI may predispose an individual to development of early hip osteoarthritis if not treated surgically (Ganz). With surgery, arthroscopic approaches are technically difficult, and may result in an incomplete resection of impinged tissues; the overall complication rate for hip arthroscopy is 1.3% (Shah). With open surgery, there is an increased risk of infection and bone death (avascular necrosis), as well as increased recovery time; individuals who return to activity too early have an increased risk for femoral neck fracture.

Source: Medical Disability Advisorhttp://www.mdguidelines.com/femoral-acetabular-impingement 


Mike Phillips & John Hart

Exercise Scientist (Phillips)

Bachelor of Human Movements. University of Queensland Australia (Phillips)

Dip Ed.(Phillips)

“Master’s In Education” (Disability) Newcastle University Australia

“Grad Cert Education” Newcastle University Australia

“Diploma Fitness/Recreation”

“Diploma of Sport and Recreation”

“Cert 4 Personal Training”

“Level 1 Strength and Conditioning Coach”

Member of ASCA (Australian Strength and Conditioning Association)

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