Dr. Harry Demos and Dr. Del Schutte, both Associate Professor of Orthopedics at MUSC, and specialists in joint reconstruction recently joined Dr. Marcy Bolster to record a podcast to address concerns regarding metal-on-metal joint replacement devices. Below, please read a summary of their thoughts on device implants and you can listen to their podcast as well.
Total hip arthroplasty is one of the most commonly performed and effective surgical procedures currently in use. Nearly 200,000 hip replacements are performed annually in the United States. Recent data reveals hip replacement to be one of the most cost-effective of all surgical procedures in terms of quality of life per health care dollar spent. Unfortunately, newer technology has not always led to an improvement in patient outcomes. A recent hip replacement design has been associated with an unacceptably high early failure rate.
By now almost everyone with a newspaper or television set has seen the advertisements by attorneys soliciting patients with “metal on metal” hip replacements. While the majority of metal on metal hip replacements may function well for many years, two specific designs have shown significant failures as soon as the first few years. The eventual outcome of other designs remains concerning, recently prompting the FDA to mandate postmarket surveillance to 21 metal on metal hip replacements manufacturers. Unfortunately these failures if not caught early enough, are associated with significant destruction of the muscles and bone in and around the hip joint. Increased concentrations of metal ions in the blood as well as in the surrounding soft tissues can be readily identified in most of these patients. Some patients, however, have normal metal ion levels and still have problems, while others may have high levels with well-functioning hips. The cause and effect relationship of metal ions and failure remains to be determined, but it is clear at this point that certain designs of metal on metal hip replacements are having a higher than expected rate of failure.
One of the most widely used metal on metal implants that has recently been recalled is the DePuy ASR hip replacement. Approximately 37,000 of these implants have been inserted in patients in the US and 93,000 world-wide. To date, revision rates are around 10%. The revisions associated with failure of the ASR implant can be much more difficult than others and should be performed by surgeons and joint replacement centers who routinely perform revisions. The loss of bone and soft tissues around the hip joint can make reconstruction much more difficult.
The implant manufacturer has an aggressive patient care program in place to facilitate and fund revision of any failures of these implants. As with any device failure, this has not happened in the majority of patients with this implant and patients with this implant may have aches and pains which do not in any way portend failure of the implant but are a normal part of life, even with a hip replacement.
We have not recommended the use of metal on metal hip replacement at the MUSC Joint Replacement Center. In the past decade of performing thousands of hip replacement procedures, only two were metal on metal hips; both for very specific indications, both of which are currently doing well. Our lack of embracing this technology is based on our experience with and concern over metal ions — years before these implants were available in the U.S. While marketing of this technology and patient demand have been high, we have continued to use metal or ceramic on crosslinked polyethylene as our implant bearing surface of choice. This bearing combination, along with stem and cup designs with a proven track record of 96-99%, has led to a very low revision rate for our patients. As a tertiary referral center, we frequently perform revision hip replacements. While we are pleased to provide this service to patients who are having problems, we are especially pleased to know that we have not yet performed a single revision hip replacement for a bearing-related issue in a patient who has a metal or ceramic on crosslinked polyethylene hip replacement that was originally performed at MUSC. If you are suffering from hip or other joint pain, please make an appointment today to see one of our orthopaedic specialists.