Hip Resurfacing or Total Hip Replacement?
Making the Right Choice
B. Sonny Bal, M.D., M.B.A.
Missouri Hip and Knee Center
In joint replacement surgery, new technologies are introduced by implant manufacturers. An example is “hip resurfacing,” which is an alternative operation to total hip replacement, for the treatment of severe hip joint arthritis. Direct consumer advertising ensures quick dissemination of new information about surgical procedures that are of interest to arthritis patients. Often, such advertising presents only the benefits of new operations, without properly discussing the attendant limitations and complications. This article is written to inform you about the two main surgical options available for hip arthritis, namely, “total hip replacement” and “hip resurfacing.”
“Total hip replacement” was developed in the late 1960s by pioneering British hip surgeon Sir John Charnley. Since then, total hip replacement has been refined extensively to its modern-day version. With minimally invasive surgery techniques, hip replacement surgery today comes close to being an outpatient procedure. For most patients with hip arthritis, a total hip replacement is the best choice. If performed properly by an experienced surgeon, the operation is minimally invasive, patients can resume full activities, no precautions need to be followed, and re-do surgery is highly unlikely during the lifetime of the patient. Modern hip replacements are the result of over 35 years of improvements in technology, implant design, bearing materials, and surgical techniques.
“Hip resurfacing” is an alternative operation for hip arthritis. This procedure was introduced in its most recent version as the “ Birmingham hip resurfacing” by the U.S. Food and Drug Administration in mid-2006. However, the operation is not new, and early hip surgeons including John Charnley had attempted hip resurfacing before giving up on it, in favor of total hip replacement. Hip resurfacing is similar to a total hip replacement. The difference is that instead of removing and replacing the arthritic hip ball, the surgeon glues a metal cap onto the hip ball. The pelvic socket is prepared identically in both procedures, so that the only difference is in what is done to the hip ball. Hip replacement involves removing the ball, and resurfacing preserves the ball.
Many orthopaedic surgeons and hospitals around the United States perform hip resurfacing; some have done so for decades. Recent advertisements and hospital web sites have promoted hip resurfacing as a new procedure, suggesting that it is better than total hip replacement surgery. Yet, there is more to hip resurfacing than the limited information presented in marketing literature. Proper information can help you make the right choice.
The first thing to recognize is that hip resurfacing is not new. Earlier versions did not prove durable because of the materials and fixation of the components. Now, newer implants and biomaterials have revived interest in hip resurfacing, and there is reason to hope that the outcomes may be long lasting.
Clinical data from Europe and Australia with the latest hip resurfacing implants show durability for ~8-10 years. Longer-term data are yet unavailable. No clinical trials have shown the clear superiority of hip resurfacing over hip replacement. There is some anecdotal evidence that hip resurfacing feels more natural and that patients are more active than those with a hip replacement. But, these observations are not validated by scientific data. Therefore, keep in mind that while local community surgeons may be enthusiastic about promoting hip resurfacing, the long-term outcomes of this operation are still unknown, even in the modern implants. In contrast, total hip replacements of several different designs have confirmed longevity of 20 years after surgery and beyond.
A limitation of hip resurfacing is that your only choice of bearing (the moving part of the artificial joint) is a cobalt-chrome alloy surface gliding against another cobalt-chrome surface. Both the ball and cup of the hip resurfacing are made this way. While the wear rates of such metal-on-metal bearings are extremely low, this technology has some potential concerns. Very rarely, a patient with a metal-on-metal bearing can develop a metal hypersensitivity reaction. Also, hip resurfacing is not recommended for women of child-bearing age and in patients with decreased kidney function. In both groups, it is speculated that the possible toxicity of metal particles could lead to future problems. Total hip replacements have more bearing choices, such as metal, ceramic, and low-wear polyethylene surfaces, in addition to metal-on-metal.
The key advantage of hip resurfacing is in preserving bone at the top end of the femur (Figures A, B, C). If a hip resurfacing fails, conversion to a hip replacement is possible. In most cases, this will involve converting the operation to a hip replacement; this can be done without removing the pelvic component (the socket). For young, active patients, this is a major advantage in terms of preserving future options. Offsetting this advantage is the fact that hip resurfacing requires a larger surgical exposure, and therefore more surgical trauma. Thus, to gain the advantage of saving bone, the patient typically has to endure a more extensive operation.
After collaborating with pioneer surgeon Dr. Joel Matta (www.hipandpelvis.com), we were able to safely adapt the minimally invasive anterior surgical approach to hip resurfacing. The first such operation was done by Dr. Matta in Los Angeles, and we performed this technique in Columbia in mid-2007. While our experience is still limited, it is unique in the U.S., and the outcomes are improved over standard surgical methods. With the anterior surgical approach, no muscles are cut, no tendons need to be severed, and the incision is shorter. Using this method, hip resurfacing can be both minimally invasive and bone-sparing. A major advantage of this technique is that if future surgery is necessary to convert the hip resurfacing to a replacement, the repeat surgery can be done through the same incision, still sparing the muscles.
Figure A shows a hip joint, which consists of a ball gliding inside a socket. Figure B shows a hip resurfacing in place. As the name implies, the arthritic surfaces of the ball and socket hip joint are shaped to accept metal resurfacing devices. In contrast, Figure C shows a total hip replacement that removes the entire arthritic ball and replaces it with an implant that is impacted inside the thigh bone. This is the only practical difference between the two operations.
For older patients, and any patient with osteoporosis, hip resurfacing is not the best choice. The reason is that the metal cap that slips over the femoral ball exerts pressure on the bone. If the bone is soft, as in elderly women, it can collapse, requiring conversion of the resurfacing to a hip replacement. Young, active patients are usually the best candidates for hip resurfacing.
Regardless of whether you have a hip resurfacing or a hip replacement, a successful operation can relieve pain, improve mobility, and make a big difference in the life of a patient with hip arthritis. Neither option should restrict the patient in any way.
The risk of repeat surgery should be understood by anyone undergoing hip resurfacing. While bone is preserved underneath the hip ball with hip resurfacing, this bone can be weakened after surgery and may break unexpectedly. Premature loosening of the metal cap covering the ball can also occur. When this occurs, the socket part does not need to be disturbed, only the femoral component needs to be changed to convert the failed hip resurfacing to a hip replacement. The hope is that these problems will not apply to the newest version of hip resurfacing, but we do not have any proof to validate this hope yet.
Every technology has its place and application. As the outcomes of modern hip resurfacing become known, it is possible that the operation is recommended more widely. Hopefully, the information here is of value to you in making an informed choice.
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