Arthroscopy of the hip in impingement

Almost everyone has a relative or friend who has undergone a hip replacement. This is a successful treatment for chronic hip joint pain, such as that caused by arthritis. However, no replacement joint so far developed is as good as a well-functioning natural joint and all replacement joints have a risk of wearing out, especially in younger and active patients, who may then need a replacement of the replacement.

Hence modern philosophy in the management of hip problems is to identify symptoms early, to see if anything can be done to repair the joint and/or prevent further damage in order to relieve symptoms and slow down the progress to arthritis, preserving the patient’s natural joint for as long as possible.

Key-hole surgery (hip arthroscopy) to repair and reshape the inside of the hip joint and bone realignment (osteotomy) to change the orientation of the socket or thigh bone are the main techniques used to protect and preserve the natural hip joint.

The hip is a ball and socket joint. The hip socket also has a soft cartilage rim called the labrum. This rim makes the socket slightly deeper, helps to keep the ball-shaped head of the femur (thigh bone) in the acetabulum (socket), and also keeps the joint lubricating fluid in place. Often the first sign of a problem with the hip is a tear in the cartilage rim (labral tear), which it thought to allow the lubricating fluid to leak out. Without lubricating fluid, the joint is more vulnerable to wear and tear damage that leads to arthritis. The joint reacts by making more fluid, which causes swelling and pain. The torn labrum can also click or catch.

Not everyone has the same hip anatomy. There is natural variation in both the shape and orientation of the femoral head and neck and in the shape and orientation of the acetabulum. The commonest variations are referred to as cam when the femoral head is shaped like slightly more oval than a perfect sphere; pincer, where the socket is slightly deeper so that the rim of the socket can pinch the neck of the femur and dysplasia where the socket is shallow. Pincer pathology can also occur when the socket is not particularly deeper, but not orientated in the ideal direction, typically pointing slightly too far backwards, termed Retroversion.

Femoroacetabular impingemnt (FAI) is a clinical syndrome, where mismatch between the shape of the ball and socket causes pinching of the labrum in certain movements. Commonly, the head of the femur is not perfectly round (cam), and as it squeezes into the socket it pinches the labrum. Impingement can also be due to the rim of the socket overhanging if it is slightly too deep (pincer), or pointing slightly backwards (retroversion). The third type of impingement is a combination of both cam and pincer types, termed mixed. If the process of pinching at the rim of joint continues, damage can spread to the articular cartilage inside of the hip causing arthritis.

While some patients can be cured with physiotherapy, others continue to limp with pain and are unable to manage their daily routine or sports, and if untreated will go on to develop hip arthritis. The aim of surgery is to reshape the bones so that no more pinching of the labrum happens. This can be done by key-hole surgery (hip arthroscopy). Typically, two to four small incisions are made. The areas of bone that are pinching the labrum are removed and the labrum is repaired or smoothed off (debridement).

Finally, many conditions can cause pain in and around the hip joint in adults. Early and thorough assessment is recommended, particularly in younger and middle-aged adults, to determine the cause and to enable hip preservation surgery and non-surgical treatments to be carried out as necessary.