Femoroacetabular Impingement


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What is Femoroacetabular Impingement?

Femoroacetabular impingement, also known as FAI, is a condition which involves the hip joint shape being abnormal due to extra bone on the ball or socket. This can cause the tissue at the front of the hip to be pinched.  Because of this friction and pinching which is caused by the femoral head (hip joint) and neck contacting the socket, damage can be sustained by different parts of the joint.

In the long term FAI may also lead to damage to the articular cartilage which covers bony surfaces in the joint, and the labrum, which is the piece of cartilage gristle that is situated on the outside of the socket.

What causes femoroacetabular impingement?

FAI arises in two forms - Cam and Pincer. CAM refers to the loss of roundness in the femoral head and neck which can lead to abnormal contact when the hip joint moves. Pincer is when there is a surplus of of bone at the edge of the socket relative to the femoral head or ball. This usually happens at the socket's front top rim, known as the acetabulum.

The effects of these two forms is the pinching of the labrum and adjacent cartilage. The Cam and Pincer forms can often occur together.

It is understood that the Cam impingement is more likely to affect young males athletes, whereas Pincer is more common in women in the 30s to 40s age bracket. There are a wide range of sports and activities which are understood to present risk factors related to FAI, including, combat sports, cycling, football, golf, cycling, tennis, ballet, weight training, hockey, ice hockey, American football, baseball and rugby. Despite these risk factors, it should be remembered that both forms can affect men or women of any age.

Symptoms of femoroacetabular impingement

In some cases, there may be no noticeable symptoms from FAI. When symptoms do arise, they can include; a 'clicking' or 'locking' feeling in the joint; pain in the groin or inner hip area, which can flare up when sitting for a long time, or after walking; difficulty putting on shoes or socks; lower back pain; pain when walking uphill; and pain in the sacroiliac joint, side of the hip, or buttocks.

Symptoms of FAI can be similar to indications of other conditions, including back pain, sports hernia and hip flexor tendinitis.


Treatment options for femoroacetabular impingement

There are non-surgical treatments which can address femoroacetabular impingement, including lifestyle changes which are conducive to maintaining the strength of the hips. A physical therapy programme can help to build strength while maximising range of movement, and activities which involve deep stretching, such as yoga, have also been found to be beneficial. If you have FAI, you might be advised to modify your participation in activities which require the hip to regularly go through large ranges of motion.

Investigations/examination for femoroacetabular impingement

Your treating doctor will take a history and carry out an examination to identify the condition.

You will require additional investigations and these may include x-rays, CT scans and MRI scans of the hip.  In some instances we may require to inject a dye into the hip before carrying out the scan.  Other investiagtions may be required to rule out other conditions.

Surgery for femoroacetabular impingement

Often before carrying out any surgical procedures, you may require injections of steroid and local anaesthetic into the joint to make sure that the diagnosis is correct.  In some instances this will completely cure the pain that you experience.

Surgical procedures to treat FAI include; hip arthroscopy, which uses an arthroscope to look inside the joint and treat damage in a minimally invasive manner; and open surgery, which typically involves a single incision of up to ten inches, which also enables the treatment of labral tears.

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