Advantages of Hip Resurfacing

The advantages of hip resurfacing over traditional total hip replacements is an area of controversy among orthopaedic surgeons. A great deal of research is currently being done on this topic.

• Hip resurfacings may be easier to revise. Because the components (called implants) used in hip replacements and hip resurfacings are mechanical parts, they can — and do — wear out or loosen over time. This typically occurs between 10 and 20 years after the procedure, although implants may last longer or shorter periods of time.

If an implant fails, an additional operation may be necessary. This second procedure is called a revision and it can be more complicated than the initial operation. Because hip resurfacing removes less bone from the femur (thighbone) than a traditional hip replacement, many surgeons believe it is easier to exchange implants that fail after hip resurfacing.

• Decreased risk of hip dislocation. In hip resurfacing, the size of the ball is larger than in a traditional hip replacement, and it is closer to the size of the natural ball of your hip. Because of this, it may be harder to dislocate. This stance is controversial because several factors can affect the risk of dislocation, such as surgical approach, and the type and size of the implants used.
• More normal walking pattern. Several studies have shown that walking patterns are more natural following hip resurfacing compared to traditional hip replacement. These differences in walking are quite subtle, however, and special instruments are needed to measure them.
• Greater hip range of motion. Hip resurfacing patients are usually able to move their hips in a greater range of motion that total hip patients. However, certain total hip implants can achieve the same range of motion as hip resurfacings.

Disadvantages of Hip Resurfacing

• Femoral neck fracture. A small percentage of hip resurfacing patients will eventually break (fracture) the thighbone at the femoral neck. If this occurs, it is usually necessary to convert the hip resurfacing into a traditional hip replacement.

A femoral neck fracture is not possible with a traditional hip replacement because the femoral neck is removed during this procedure. However, fractures around the implants can still occur with a traditional hip replacement.

• Metal ion risk. In hip resurfacing, a metal ball moves within a metal socket. Over time, this leads to the production of tiny metal particles called ions. Some patients may develop sensitivity or allergy to the metal particles, which may cause pain and swelling. Also, there are concerns that the metal particles may increase the risk of cancer, although this has never been proven. Some types of traditional hip replacements also consist of a metal ball and a metal socket and these replacements run the same potential risks.
• Hip resurfacing is a more difficult operation. Hip resurfacings are more difficult that total hip replacements for surgeons to perform. As such, a larger incision is usually required for a hip resurfacing.

(Left) In the x-ray of a hip resurfacing taken from the front, a metal cap now covers the femoral head, and a small stem is seen in the femoral neck. A metal socket is also in place. Unlike the traditional total hip replacement shown on the right, the femoral head and neck are not removed.

Before Surgery

You will likely be admitted to the hospital on the day of surgery.

Before your procedure, a doctor from the anesthesia department will evaluate you. He or she will review your medical history and discuss anesthesia choices with you. You should also have discussed anesthesia choices with your surgeon during your preoperative clinic visits. Anesthesia can be either general (you are put to sleep) or spinal (you are awake but your body is numb from the waist down).

Your surgeon will also see you before surgery and sign your hip to verify the surgical site.

Surgical Procedure

A hip resurfacing operation typically lasts between 1 1/2 and 3 hours.

Your surgeon will make an incision in your thigh in order to reach the hip joint. The femoral head is then dislocated out of the socket. Next, the head is trimmed with specially designed power instruments. A metal cap is cemented over the prepared femoral head. The cartilage that lines the socket is removed with a power tool called a reamer. A metal cup is then pushed into the socket and held in place by friction between the bone and the metal. Once the cup is in place, the femoral head is relocated back into the socket and the incision is closed.

After the surgery you will be taken to the recovery room, where you will be closely monitored by nurses as you recover from the anesthesia. You will then be taken to your hospital room.