Problems With Metal-on-Metal Hip Replacements Attract Federal Scrutiny

July 22, 2011

Every year, about a quarter of a million Americans undergo hip replacement procedures. For a third of them, metal-on-metal ("MoM") implants are used to replace worn-out or damaged hip joints. MoM hip replacements were once believed to be more durable than other available counterparts. But growing concerns over the safety of these hip replacement devices have many medical experts cautioning that MoM replacements should be used far more sparingly, if at all.

What Is a Metal-on-Metal Hip Implant?

In a procedure for hip replacement, the ball at the top of the femur (thigh bone) is removed and replaced, and a stem is inserted into the femur for support. Then, the socket is replaced by an implanted cup, thereby creating a completely prosthetic hip joint.

In the United States, the artificial ball and socket may currently be made out of four different combinations of materials: a metal ball and a plastic socket, a ceramic ball and a plastic socket, a ceramic ball and a ceramic socket, or a metal ball and a metal socket (a MoM-type implant).

In a related type of surgery, hip resurfacing, the ball of the femur is capped and worn-out materials in the socket are replaced by metal components. In hip resurfacing, all implanted materials are made out of metal.

Safety Concerns Regarding MoM Hip Implants

While there are risks associated with all types of hip replacement, and every surgery in general, there is a growing body of medical evidence that indicates patients who received a Metal-on-Metal implant may be particularly susceptible to certain complications.

Typically, the ball and socket components of MoM replacement joints are made out of metals like cobalt and chromium. Although artificial hips are designed to last for 15 or more years, studies have found that wear can begin to take a heavy toll on MoM devices far more quickly than previously expected.

When an individual with a MoM hip implant walks or runs, the metal ball and socket in his or her hip joint rub against each other. This can cause microscopic particles of metal to wear off and enter the body tissues surrounding the MoM device.

In some instances, metal particles building up around the joint lead to an adverse reaction in nearby tissues. This can be very painful, and may loosen the replacement joint. Surgical intervention may ultimately be necessary to supplant the old MoM implant with another artificial hip.

A separate problem may arise if metal particles enter the bloodstream: heightened concentrations of cobalt and chromium ions in the blood can cause damage throughout the body. For instance, medical journals have reported adverse effects on the heart, nervous system and thyroid glands of some patients with MoM hip replacements.

The FDA Issues Orders to MoM Manufacturers

In early May, the Food and Drug Administration ("FDA") finally took action and issued orders to 21 manufacturers of MoM hip replacements. These orders will require the companies to provide additional studies regarding the possible adverse health consequences of the implants.

Each of the aforementioned companies will have to give the FDA a well-developed research plan to uncover, among other things, the ratio of hip replacement patients who experienced problems, exactly what medical issues have been encountered, and the rate at which cobalt and chromium blood levels increase in MoM recipients. After continuing their surveillance of MoM hip replacement systems and examining the results of the research protocols, the FDA will consider whether further action is warranted.

Patients With Metal-on-Metal Implants

Doctors at the nation's leading orthopedic hospitals have recently seen an influx in the number of patients receiving treatment for complications arising out of the metal particles shed by their MoM hip replacements. Some leading physicians are even urging their peers to refrain from using MoM hip components whenever possible. In leading institutions like the Mayo Clinic, surgeons have drastically reduced the number of MoM replacements being implanted, choosing instead to use other materials until more complete research outlining the possible side effects of MoM devices can be produced.

If you or a loved one has received a MoM hip replacement, watch carefully for any signs of pain or swelling near the hip joint or an impairment in walking ability. In addition, as general health changes could be symptoms of metal particles in the bloodstream, take immediate action if you notice chest pain, weakness, fatigue, impaired hearing or vision, changes in urination, or any other major symptoms. Keep in mind that early reports indicate women are much more likely than men to suffer negative effects from MoM hip replacements.

If you observe any indicia of trouble relating to a MoM hip replacement, contact your orthopedic surgeon immediately for further evaluation. In addition, you should contact an attorney experienced in defective medical devices to explore you legal options: you may be entitled to compensation from manufacturers who rushed poorly-designed or improperly-tested MoM hip replacement devices to market.

Article provided by Babbitt, Johnson, Osborne & Le Clainche, P.A.
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