It's not exactly news – as far back as 2009, the U.K.'s National Joint Registry reported that metal-on-metal hip replacements are more prone to failure than those made from other materials. It's also well known that DePuy Orthopedics has the highest failure rate of all – a whopping 33%.
Although the procedure and the devices can vary, a hip replacement is essentially a prosthetic replacement of the femoral head, which is the ball atop the thigh bone that fits into the hip socket. When the natural bone is injured or has become arthritic, this ball is removed and the artificial one set into the thighbone. A socket is implanted into the hip itself; this is known as the actetabular cup.
It's not unlike the ball joints in the front end of an automobile that connect the control arms to the steering knuckles. Of course, an automobile is not a human body. Both automotive ball joints and metal hip implants then to degrade and wear down over time – but while this is an inconvenience in a car, it has disastrous consequences for human health as these tiny bits of metal enter the bloodstream and tissues, causing a range of symptoms ranging from skin rashes to necrosis (death of the tissues).
The polyethylene plastic that has also been used is not much better; tiny bits of this material also grinds away and enters the system, causing bone loss and inflammation. Ceramic is another material that has been used, but not only can ceramic implants cause an annoying squeaking sound, they can also break – and the results can be unpleasant for the patient, to say the least.
Since the late 19th Century, doctors involved in the research and development of hip implantation (the medical term is hip arthroplasty) have experimented in a wide range of materials. One of the earliest attempts was an implant made from ivory, attached to the femur with nickel-plated screws, invented by one Dr. Themistocles Gluck of Germany. The first modern metal implant was done in 1940 at Johns Hopkins by a Dr. Austin Moore.
Metal implants were considered to be the most innovative development, providing greater durability. (hip implants generally don't last more than fifteen years before they must be replaced). Current events are proving otherwise, however.
What is even more shocking however is that, despite the number of complaints from consumers and their advocates, the FDA is doing a poor job of tracking these hip plants; so far, most of the information on these failures is coming from the U.K. and Australia. It's not surprising, however – since so many U.S. government agencies have become little more than handmaidens to private industry.
Gomez, Pablo F. and Jose Morcuende. "Early Attempts at Arthroplasty." Iowa Journal of Orthopedics, vol. 25 (2005).
Kappes, Scott. "Report: Metal-On-Metal hips Fail More Often. (Houston) InjuryBoard Blog Network (http://houston.injuryboard.com/medical-devices-and-implants/report-metalonmetal-hips-fail-more-often.aspx?googleid=294296 ). Updated 15 September 2011. Retrieved 20 September 2011.
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