Metal-on-Metal Hip Implant Parts Linked to Reports of Problems

Health care professionals are warning of increasing signs of problems with metal-on-metal hip implants, which could affect up to 3 percent of all recipients.

The warnings, highlighted in a story by the New York Times, come from surgeons and hip specialists who say that metal particles shed into the body as the hip implants wear down can cause complications. A number of studies have brought attention to the problem as the popularity of the metal hip implant parts has spread in recent years.

The “metal on metal” hip implants account for about one-third of the 250,000 hip replacements performed each year in the U.S. They became popular due to the belief that the metal structure, usually chromium or cobalt, would be more durable than other types of hip implants. However, after a series of studies over the last couple years, surgeons are warning that one to three percent of all metal on metal hip implant recipients may experience hip failure, and possibly need to have the devices replaced, due to metallic debris.

The metal particles are shed into the body as the devices wear down, particularly in the ball-and-socket joints. The metal particles can damage soft tissue, cause inflammatory reactions and lead to bone loss.

Last year, U.K. researchers studied 660 patients who had received metal hip implants from DePuy Orthopaedics and found that 3.4 percent suffered from adverse reactions to metal debris.

Canadian researchers also reported last year that patients who received the Zimmer Durom hip replacement system had different levels of metallic ions in their bloodstream than people who did not have the implant. Researchers found that Zimmer Durom Cup recipients had much higher levels of chromium and cobalt in their blood than those who underwent other procedures.

Zimmer already faces a number of lawsuits over other problems with the Zimmer Durom Cup hip implant. A temporary Zimmer Durom Cup recall was previously issued in 2008, due to a high number of hip replacement failures associated with the product. Sales were suspended during the Durom Cup recall and the product was reintroduced with new warning labels and instructions for surgeons on techniques needed to avoid the risk of complications. The Canadian study, underwritten by Zimmer, called for revised Zimmer Durom Cup to be recalled as well.

A number of plaintiffs have filed Zimmer Durom Cup lawsuits alleging they had experienced cup failures, leaving them in constant pain and requiring additional medical treatments and surgery.

All of the major orthopedic medical device companies manufacture their own version of “metal on metal” hip implants, and several have said that the metallic debris problem does not pose a significant risk. However, an increasing number of orthopaedic surgeons and experts disagree. In a recent editorial in the Journal of Arthroplasty, the medical journal warned doctors to avoid the use of the metal hip implants, and said they should only be used “with great caution.”