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Bad bearings

By Stephen S. Tower, MD

Source: click here

Lessons learned from failures of this generation of MoM hip implants

I believe that we, as orthopaedic surgeons, are obligated to stop implanting metal-on-metal (MoM) hip implants. I also believe that, whenever possible, patients already implanted should be monitored for the complications of arthroprosthetic cobaltism. The development, regulation, marketing, and dissemination of the current MoM hip implants bear study and should be thoroughly reviewed.

I am biased on this topic. My opinions are founded in my experience as a patient who received an MoM hip implant and as a surgeon who performs revision hip arthroplasty. After 4 years of study of myself, my patients, and the literature on MoM bearings and cobalt toxicity, I detailed what I learned in articles in The Journal of Bone and Joint Surgery—American and in Alaska Medicine.

The fundamental basis of our actions is to benefit our patients. Once we accept a patient into our care, we are obligated to place the patient’s needs above our economic interest. We do generally profit from the care of our patients, and every time we consider surgery for a patient, introspection is required to confirm that the patient’s needs are foremost. Any surgical intervention should be weighed on its possible risks and benefits compared to alternative treatments. The choice of arthroprosthetic implants is integral in this equation.

I believe that today’s MoM hip resurfacing arthroplasty is more revision-prone than the metal-on-polyethylene (MoP) hip arthroplasty of the 1970s. I also believe that, due to the periprosthetic tissue response to chrome and cobalt metal debris, revision of a failed MoM hip implant is likely to be more complex and more likely to be repeated than revision of a failed MoP hip implant. The literature to date, in my opinion, has not shown advantages for a resurfacing-sized MoM bearing compared to a 32- to 36-millimeter MoP one.

As orthopaedic surgeons, we have obligations to our patients and a duty to society. If our choice of arthroprosthetic implants commonly results in arthroplasties that are less durable, patients and society are poorly served. I hope this will not become a worldwide surgical tragedy. I suspect that Web-based direct marketing of MoM hip resurfacing arthroplasty to patients, disguised as patient advocacy and education, has fueled the demand for this flawed procedure.

Stephen S. Tower, MD, is an AAOS fellow in private practice in Anchorage, Alaska. Dr. Tower specializes in joint replacement surgery. He can be reached at stephentower@mac.com

AAOS Now
February 2011 Issue
http://www.aaos.org/news/aaosnow/feb11/clinical3.asp

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