FROM THE EDITORS
Choosing the right total hip replacement
Rafael J. Sierra, M.D.
It has been close to 40 years since the first Food and Drug Administration-approved total hip replacement performed in the United States was done at Mayo Clinic. The total hip replacement available at that time — called the Charnley hip apparatus — had a smooth, polished stainless steel stem and a plastic socket. Both pieces were cemented or glued into place. Many of these hip replacements lasted for years as evidenced by several long-term follow-up studies done 25 to 30 years later.
Back then, there was very little consideration given to the type of hip replacement to be done, as there were only a few choices. Total hip replacement has progressed rapidly over the past decades. Major advances have occurred, and there are multiple total hip replacements available. For example, the majority of hip replacements implanted in the United States today aren't cemented into place, but are put in so that bone grows into the implants, anchoring them in place. Cemented stems, however, have a very long track record and continue to work very well in many people.
In the last 10 years, major improvements in the artificial bearing surfaces of implants have been approved for use in the U.S. These include hard-on-hard bearing surfaces — ceramic-on-ceramic or metal-on-metal — and also advanced plastics such as highly cross-linked polyethylene. This could make hip replacements last even longer. But only time will tell if they function better than do previous implants.
The choice of one type of hip replacement over another has become one of the most important preoperative decisions made by both patient and surgeon. Choosing the artificial bearing surface of your implant is where most preoperative decision making comes into play. It is not uncommon to hear terms such as "metal-on-metal," or "porcelain hip," when discussing options in this area. Additional advances also may be discussed. For example, you may hear terms such as "capping the femur" or "minimally invasive surgery." Although these advances may work well in many people, not everyone is a suitable candidate for these types of hip replacements. The decision to proceed with one type of hip replacement over another should be based on the knowledge about past and current technology, its potential durability based on laboratory testing and clinical use, and the drawbacks of its use. Yes, drawbacks: The majority of the newer implants or surgical techniques used to implant them have been shown to have implant- or patient-specific drawbacks.
Smaller incision total hip replacement, for example, may not provide a faster recovery. In addition, a smaller incision can sometimes be detrimental in adequately placing implants.
Ceramic-on-ceramic total hip replacement has lost favor because of the documented squeaking, which may occur in 1 to 2 percent of patients.
Total hip resurfacing — or capping the femur — may work well for some people, but not in others and in certain groups may increase the risk of femur neck fracture. Currently, it can only be done with metal-on-metal bearing surfaces and not everyone is a good candidate for these bearing surfaces. That's because metal-on-metal hip replacement has the potential downsides of allergy and hypersensitivity reactions — which may occur in one out of 1,000 patients. There are also fears of elevated metal ion levels in the bloodstream that could potentially cause detrimental long-term health problems, but this potential problem is purely theoretical and has not been proved in humans despite decades of use.
Total hip replacement has worked extremely well for many years. Implants and technology will continue to evolve and benefit those who are undergoing total hip replacement. However, before making a decision about what type of hip replacement is best for you, understand the known risks and benefits of what is available for use, and remember that new may not mean better or longer.