Hip Resurfacing: Not So Good for Women

We're chiropractors, not surgeons, so why do we need to know about hip replacement procedures? Because we have patients who have hip replacements and we are treating them for symptoms that may be associated with the hip replacement. I'm not going to review how to perform an orthopedic exam, nor am I going to review how to take films of total hip replacements. This is a brief "heads up" on the problems with a fairly new surgical treatment for arthritic hips called hip resurfacing.

In a traditional hip replacement, the head and neck of the femur are removed and replaced with a prosthesis. In a hip resurfacing, most of the head and neck are preserved and an artificial cap is placed over the head of the femur. The idea is to preserve as much of the femur as possible and postpone the need for a total hip replacement a decade later. The procedure is aimed at middle-age patients who are physically active and are expected to outlive the normal 15-to-20-year lifespan of a full hip replacement. Sounds very logical, and many people have benefited from the procedure.

However, studies from some countries where resurfacing has been used longer than in the United States, including England, Sweden and Australia, have repeatedly shown a higher failure rate for women who undergo the procedure than for men. A recent British study released in September 2008 by the Royal College of Surgeons of England found that 3.7 percent of the 2,360 women who underwent resurfacing in England had to have a second operation to repair the same hip within three years.³ That compared with a rate of follow-up surgeries of 1.6 percent or less for women who received traditional hip replacements. The most frequent cause of failure is fracture.

The problems with hip resurfacing in some women first emerged in places like Australia, Sweden and England that operate databases, known as registries, which regularly track the outcomes of orthopedic procedures and are publicly available. The United States does not have such a national tracking system. I know I am diverging just a little, but it is amazing that the U.S. does not have a joint replacement registry. Registries in other countries benefit everyone involved. The surgeons benefit from receiving more timely data that could improve patient outcomes, and the manufacturers benefit by knowing how their implants are performing. It helps determine which products are poor performers and should be removed from the market. It can also act as a benchmark for determining truth in advertising, as the manufactures who inflate their results will become readily apparent.

But back to the issue of hip resurfacing - I believe it is very important that we chiropractors know what type of hip surgery a patient has undergone, particularly if manual manipulation is being considered. A female patient with hip joint resurfacing should raise a red flag.¹ The most common reason for failure of hip resurfacing is fracture. It does not take much force to fracture these resurfaced hips if they are about to fail. I know of one patient who simply crossed one leg over the other and the prosthesis failed. Of course, this is just one case and most likely a very rare occurrence, but it got my attention.

Because of this experience, I suggest we be very careful with manual manipulation that might affect a hip that has been resurfaced. My reasoning is that these patients may already be experiencing failure of the prosthesis and it is only a matter of timing as to when the fracture may occur. Special care should be taking to rule out the possibility of fracture. Recent films should be compared to postop films. A bone scan or MRI of the hip should be performed to rule out a stress or occult fracture. Even after ruling out any possible problems with the prosthesis, I would recommend avoiding using the hip as a fulcrum.

If any of your patients are considering hip resurfacing (particularly female patients), I would make them aware of the potential problems. The head researcher of the English study, Dr. Jan H. van der Meulen, has gone so far as to suggest, in an article in TheNew York Times, that the procedure should be limited to men unless other factors come into play.²

In the U.S. last year, resurfacing represented only a small fraction of the 430,000 hip replacements that occurred; about 10,000 to 15,000 cases.² But that number is expected to increase by 40 percent to 50 percent. Patients see advertisements or hear from others about advantages of hip resurfacing in younger adults - all without scientific evidence - and want the procedure.  

If your patients are in need of a total hip replacement, I suggest you inform them of the potential problems and encourage them to have a frank discussion with their surgeon about the alternatives available. Also tell patients to ask about possible conflicts or ties to the manufacturer involving the implants the doctor is recommending. And as always, tell them that when considering surgery, seek a second opinion.

References

1. Della Valle CJ, Nunley RM, Raterman SJ, Barrack RL. Initial American experience with hip resurfacing following FDA approval. Clin Orthop Relat Res, January 2009;467(1):72-8.
2. Meier B. "For Women, Red Flags About a Hip Device."New York Times, Nov. 8, 2008. 
3. Sibanda N, Copley LP. Lewsey JD, et al. Revision rates after primary hip and knee replacement in England between 2003 and 2006. PLoS Med, September 2008;5(9):e179.