Unusually high failure rates have lead to serious concerns about metal-on-metal hip implants and the short and long-term consequences.

Although all hip prostheses are subject to wear and tear, the risks of metal-on-metal implants are unique – and the effects on a patient’s health can be severe, ranging from severe pain and loss of motion to metal toxicity.

The premature failure rate of metal-on-metal (MoM) hip prostheses have been a cause of action in numerous lawsuits in which plaintiffs have alleged defective design, negligence and breach of warranty.

Companies such as Johnson & Johnson subsidiary DePuy Orthopaedics, Stryker, and Wright Medical have all been named defendants in MoM hip implant litigation, which has resulted in judgments in favor of plaintiffs in the 7 and 8-figure range.

Hip Surgery: a Brief History

The first known attempt at total hip arthroplasty took place in Germany in 1891. Dr. Themistocles Gluck (1853-1942) was one of the pioneers of joint replacement surgery, having performed the first successful knee replacement on a 17-year-old girl a year earlier. His surgical technique used an artificial femoral head made from ivory, which was then fixed in place using nickel-plated screws, plaster of Paris and a specially-formulated adhesive.

The first metal-on-metal hip was implanted in 1940 at Columbia Hospital in South Carolina by Dr. Austin Moore, another trailblazer in the field of joint arthroplasty. His prosthesis consisted of a femoral stem that was inserted into the top of the patient’s femur (thighbone), with a head made from an alloy of cobalt and chromium. The basic concept is still used today.

Increasing Concerns About Metal-on-Metal Hip Implants

By 2010, a growing number of articles published in orthopedic journals reported premature failure of MoM hip prostheses. These have been attributed to defective design, particularly among those made from heat-treated alloys. Alarmingly, complications resulting from these failures involved a form of metal biotoxicity, known as metallosis.

This was caused by the release of minuscule bits of metal or metal ions due to component wear. These minute metal shards have been known to lodge in adjacent tissues, causing necrosis, inflammation, pain, and disability. The metal can also enter the bloodstream, resulting in neurological and physiological illnesses and severe immune reactions. Revision surgery is required in up to 3 percent of cases.

In March 2012, a study appeared in The Lancet that found MoM hip replacements were failing at over three times that of metal-on-plastic and ceramic hip implants. The authors of the study called for a complete ban on the use of MoM hip implants.

Is 510(k) Premarket Notification to Blame?

Although the U.S. Food and Drug Administration issued an advisory about metal hip implants in February of 2011, it was not until June of the following year that the idea of setting new standards was even discussed. Ultimately, no standards have been set – only “guidelines.”

Furthermore, the FDA has not required many of these metal-on-metal hip implants to undergo full clinical testing before allowing them onto the market. This is due to a loophole known as 510(k) Premarket Notification, that only requires a manufacturer to demonstrate that its product is “substantially equivalent” to similar products previously approved for the market. Due to the high rates of premature failure, the FDA has announced that clinical studies and post-market tracking will be required for MoM hip prostheses in the future.