Metal-on-Metal Hip Failures Often Happen In First Two Years: Study

More than three-quarters of all failures involving metal-on-metal hip replacement systems occur within two years after surgery, according to the findings of a new study. 

Metal-on-metal hip replacements are a controversial design, which gained popularity over the past decade, before concerns emerged about an increased risk of failure and other problems caused by the microscopic metal particles that are released as the metal parts of the implant rub against each other.

In this month’s issue of the medical journal Orthopedics, U.S. researchers found that most metal-on-metal hip implant failures occur within a few years after being implanted, although such devices are designed to last 15 to 20 years. The failures are usually caused by aseptic acetabular loosening, often requiring revision surgery, according to the findings.

Researchers conducted a review of 80 patients who underwent revision surgery to removed failed metal-on-metal artificial hips. They found that 78% of those patients had the revisions within two years of getting the implant, and 98% had the metal hips removed within the first three years. Metal-on-metal hip replacement systems are supposed to last much longer.

The investigation also revealed that 13% of those who needed revision surgery suffered from localized soft tissue reactions, which most experts believe is caused by the metal debris generated by the parts rubbing together, a condition known as metallosis.

Concerns About Metal-on-Metal Hips Failing

The study adds to the body of evidence that has raised significant concerns regarding metal-on-metal hip replacement systems. Last month, an FDA advisory committee convened to discuss the safety issues surrounding the implants and advised that anyone who has an all-metal artificial hip get it X-rayed annually to check for problems. Those suffering pain and discomfort should also have a blood test to look for signs of chromium and cobalt ions, key indicators of metallosis.

The advisory committee members also noted that there appeared to be almost no reason to use metal-on-metal hip implants.

Sales of metal-on-metal hip replacements have fallen sharply over the past two years, and more research has been focused on the impact of these microscopic particles entering the blood stream since a recall was issued for DePuy ASR hip implants in August 2010.

The Johnson & Johnson subsidiary Depuy Orthopedics issued an ASR hip recall after acknowledging that 12% to 13% of the implants were found to fail within the first five years. Since that time, thousands of DePuy ASR hip lawsuits have been filed against the manufacturer alleging that they failed to adequately research the design or warn about the risk of failures.

Similar product liability lawsuits have also been filed over other metal-on-metal implants, including the DePuy Pinnacle hip, Biomet M2A-Magnum hip and Wright Conserve hip.

Metal Concerns From Modular Hip Replacements

In addition to concerns surrounding metal-on-metal hip replacements, which feature a metal ball that rotates within a metal cup, recently similar problems have surfaced with the release of metallic debris among modular hip components, which feature a metal neck that fits within a metal stem to allow the surgeon to adjust the length of the femoral component to fit the patient.

Earlier this month, a Stryker Rejuvenate hip recall was issued after it was discovered that the metal contact between the two components of the modular neck stems used in the system was associated with an increased risk of fretting and corrosion, which has been found to result in pain, swelling, local tissue reactions and early failure of the hip replacement.

A number of lawsuits over failed Stryker modular hip replacmements are also now being reviewed by attorneys throughout the United States, and serious questions remain about the safety of any implants that feature direct metal-on-metal contact that bears the weight of the body during normal daily movements.