A diagram showing cam type impingement

Hip Impingement

The hip joint is a ball and socket type of joint which allows a wide range of motion. Impingement of the hip is a condition in which the ball and socket are not entirely symmetrical causing the two to pinch together during certain types of movement.  The most common type is called “cam” impingement in which the ball (femoral head) is slightly egg shaped or eccentric. This is cause by extra bone deposited on the from of the ball of the hip joint from the growth plate closing at the time of adulthood.  Common symptoms are sharp pain in the groin area after strenuous activity such as jogging or jumping. This condition is far more common in men than in women (9:1 male to female).  The clinical picture is a spectrum from mild intermittent irritation of the joint to persistent groin pain, degenerative bone spurs and chronic cartilage damage.  There is some data to suggest that chronic untreated impingement may be a common cause of arthritis in men.

An MRI arthrogram showing extra bone on the femoral neck

Pincer type femoral-acetabular impingement (FAI) is caused by an abnormality on the cup side of the hip joint.  This leads to a chronic pinching of the labrum and patients often present with a labral tear.  This type of FAI is more common in women (7:1 female to male). Unfortunately, many patients presenting with labral tears have their treatment aimed at fixing the labrum rather than solving the impingement problem.  Many of these patients will have an arthroscopy for a labral tear and report a period of relief only to have the symptoms return again.  This cycle generally repeats until the anterior acetabular (bony) abnormality is corrected.

A diagram showing pincher type impingement

Treatment is tailored to each patient taking into consideration their activity level and severity of the impingement. There is some controversy over the appropriate method of treatment for both cam and pincer type impingements. Mild cases can be treated with medication and occasionally corticosteroid injection while I recommend arthroscopic decompression in more moderate cases. Arthroscopic decompression is usually quite effective for cam type impingements but the results for pincer type impingement are much less encouraging because of the difficulty in decompressing the acetabular side of the joint.  For more advanced cases, or in those patients who have failed arthroscopic decompression,  I will recommend a formal open joint decompression and repair of the labrum (a dense ring of tissue surrounding the hip socket). If left untreated, most cases will progress gradually and many will require joint replacement later in life.