Hip Anatomy
The hip joint is composed of a ball and socket from two separate bones, the femur (thigh bone) and the pelvis. The pelvis features cup-shaped depression called the acetabulum (socket). The femur is connected with the pelvis at the hip joint. The head of the femur, shaped like a ball, fits tightly into the acetabulum forming the ball and socket joint of the hip, allowing the leg to move forward and backward, side to side and rotate right and left. The acetabulum and femoral head are lined with cartilage, which cushions the bones during weight-bearing activities and allows the joint to rotate smoothly and freely in all planes of movement with minimal friction.

Arthritis of the Hip
Arthritis of the hip is a disease which causes wearing away of the cartilage between the femoral head and the acetabulum, triggering the two bones to scrape against each other, raw bone on raw bone. When this happens, the joint becomes pitted, eroded and uneven, resulting in pain, stiffness and instability. In some cases, motion of the leg may be greatly restricted.

The condition of osteoarthritis is commonly referred to as “wear and tear” arthritis. This degenerative process can be aggravated by hip injury or avascular necrosis of femoral head. Some experts believe that there might be genetic predisposition in people who develop osteoarthritis of the hip. Osteoarthritis of the hip is the most common cause for total hip replacement.

during their lifetime- hence the resurfacing procedure offers potentially significant advantages in this group.

Total Hip Resurfacing
Hip Resurfacing is a new technology of hip replacement which replaces the two surfaces of the hip joint. The procedure is very bone conserving as the head of the femur is retained. Instead of removing the head completely, it is shaped to accept an anatomically sized metal sphere. There is no large stem to go down the central part of the femur and the surface of the acetabulum or the socket is also replaced with a metal implant, which is wedged directly into the bone.

The resurfacing components are made of ‘as-cast’ cobalt chrome which is finely machined to produce a very high quality surface with a low friction finish, hence low wear. The BIRMINGHAM hip resurfacing has the largest independently verified clinical history of any resurfacing device available today.

Candidate for Hip Resurfacing
The operation is primarily intended for use in people who are in need of a hip replacement at a younger age. However there are certain conditions where this technique cannot be used, e.g. if someone has an extreme deformity of either the head of the femur or the acetabulum, the hip resurfacing will not be a suitable procedure.

For people requiring a hip replacement under the age of 55, regular consideration is given for this procedure. People aged between 55 and 65, who are very active and otherwise fit, may also be suitable and this will be determined by their bone quality.

Results of Hip Resurfacing
Studies show and support that hip resurfacing in young patients under RSA tracking technology can be as good as conventional hip replacement in old patient and can last for a period of 10-15 years or more. The historical metal on metal prosthesis in numerous patients had been shown to last in excess of 30 years. With modern manufacturing and quality control techniques, we consider that these would improve the longevity of metal on metal prosthesis more than in the past.

Disadvantages of Hip Resurfacing
The main disadvantage lies in not knowing the long term results. However the results to date indicate that the success rates of hip resurfacing in young patient after the first 5-10 years are better than those of conventional total hip replacement. Although the operation for hip resurfacing is similar to a conventional total hip replacement, in some ways it is a more demanding surgical technique.

Although there are the usual risks associated with any hip replacement, there is a very low risk of major complications due to infection or early loosening, thus minimizing the need for further surgery. There is a very slim chance of leg lengths being different. There is also a very low risk of developing major medical complications such as thrombosis, heart attack or stroke, which can happen due to any surgery requiring a general anesthesia.

Summary
Although total hip resurfacing is relatively a new procedure, it holds out great promise for the younger, more active, high demand patient as it permits a full return to normal activity. These modern generations of metal on metal resurfacing prosthesis and improved techniques for fixation are leaving behind the deficiencies of the earlier developmental designs. Patients enjoy a long term good quality of life as opposed to conventional total hip replacement.