Hip resurfacing

Hip Resurfacing is form of arthroplasty which has been developed as an earlier intervention alternative to total hip replacement (THR). The potential advantages of hip resurfacing include less bone removal (bone preservation), a potentially lower number of hip dislocations due to a relatively larger femoral head size, and possibly easier revision surgery for a subsequent total hip replacment device because a surgeon could have more bone stock available to work with. The potential disadvantages of hip resurfacing are femoral neck fractures (rate of 3-6%), aseptic loosening, and metal wear.

Patient suitability for hip resurfacing is decided by the patient's anatomy and the patient's doctor. Hip resurfacing is intended for younger patients who are not morbidly obese, are clinically qualified for a hip replacement (determined by the doctor), have been diagnosed with noninflammatory degenerative joint disease, do not have an infection, and are not allergic to the metals used in the implant. Hip resurfacing should not be used on patients who have severe bone loss in their femoral head, those with large femoral neck cysts present (typically found at surgery), or patients who have poor bone stock in the acetabulum. Caution should be used for patients who have rheumatoid arthritis, are tall, thin, or female, those with osteonecrosis (poor blood supply) to the femoral head, or those with femoral head cysts > 1cm on an x-ray taken before surgery. Patients with any of these conditions may not be suitable candidates for hip resurfacing.

In the United States, the FDA approved hip resurfacing using the Birmingham Hip Resurfacing (BHR) on May 9, 2006. Derek McMinn designed the Birmingham Hip Resurfacing in Birmingham, England and released it for use in the UK in July 1997. Both BIRMINGHAM HIP and BHR are registered trade marks of Smith & Nephew, who are now the exclusive manufacturers and distributors of the BIRMINGHAM HIP Resurfacing System. On July 3, 2007, the FDA approved an alternative hip resurfacing system made in the UK by Corin Group and marketed in the US by Stryker. . Stryker/Corin also recently received FDA approval for their resurfacing product in the US.

The BHR is a metal on metal hip device which differs from a total hip replacement device because it may be bone conserving. A THR requires that the upper portion of the femur bone be cut off to accept the stem portion of a THR hip device. The femur cap of the BHR does not require the femur bone be cut off, it is shaped to accept the cap. Both techniques require that a cup is placed in the acetabulum of the hip socket. The main advantage of the bone conserving system of the BHR is that when a revision is required, there is still a complete femur bone left for a THR stem. When a THR requires a revision, what is left of the femur bone must be broken apart to remove the stem and then the bone is wired together again to heal. Having a BHR at a younger age means that a revision may be easier to perform when required.

Disadvantages and potential risk with BHR resurfacing include the following:

1.) Higher risk for failure compared with THR (resurfacing is generally done with the expectation that the patient will need later THR surgery). 2.) Requires a much larger surgical incision than THR which can lengthen recovery and increase the risk of infection. 3.) Unlike THR, surgeon can not adjust leg length or offset with resurfacing - incorrect leg length can lead to limping. 4.) Resurfacing does not have the same robust, proven clinical history as THR. 5.) Resurfacing is a highly complex surgical procedure which requires a very experienced surgeon in order to minimize the risk of failure. 6.) Only a small segment of patients are the right candidates for resurfacing - patients who do not meet all specific criteria for the procedure are at a much higher risk for compications and future surgeries.

Hip resurfacing may allow younger, active people to return to any activities they enjoyed previous to their hip problems. The large size cap and cup of the BHR are the same size as a person's original femur bone and are designed to prevent dislocations. There are many athletes with resurfaced hips that continue to compete at the professional level in a myraid of activities. They include:
 * Cory Foulk finished a marathon three months after his surgery, and finished 11th in the Ultraman world championship eleven months later
 * Jim Roxburgh continues to participate in the martial arts after having both hips resurfaced in 2004
 * Ian MacLaren of the Torashin Karate Club is believed to be the first 5th dan Karate-ka in the world to have had both hips resurfaced
 * Floyd Landis, 2006 Tour de France Winner

New Developments in resurfacing:

DePuy, Johnson & Johnson recently submitted their clinical data to the FDA for approval of their ASR Surface Replacement System. Approval date is not know, but analysts suggest some time in late 2008. The ASR System is believed to have better bone preserving characteristics and the design of the bearings will produce the lowest wear of any resurfacing system.

Alternatives to resurfacing:

There is new technology available today with THR that offer all of the benefits of resurfacing without the potential risks. Newer bone preserving femoral stems and large diameter metal-on-metal bearings provide excellent outcomes for younger, more active patients. One example is DePuy Johnson & Johnson's ASR XL Hip System. This system provides a large metal femoral head which matches the patient's natural anatomy, paired with a one-piece metal acetabular cup. The femoral head can be placed on a bone preserving femoral stem which has over 30 years clinical heritage. The ASR XL System is believed to produce extremely low wear and excellent range of motion. Below are advantages of systems like ASR XL compared to resurfacing:

1.) Require a smaller surgical incision. 2.) Allow surgeons to adjust leg length and offset. 3.) Are based on more robust, proven clinical heritage. 4.) Provide more range of motion. 5.) Are generally easier for surgeons to implant. 6.) Have lower failure rates.