MRI May Detect Metal-on-Metal Hip Tissue Damage: Study

Magnetic resonance imaging (MRI) exams may be used to detect developing problems with metal-on-metal hip replacements before patients start showing symptoms, according to a new study.  

Researchers from the Hospital for Special Surgery published a study in the Journal of Bone & Joint Surgery, which indicates that joint inflammation was present in most patients with failed metal-on-metal hip replacement systems long before other symptoms appeared. That inflammation of the joint lining, known as synovotis, can be detected by an MRI scan.

The investigators looked at 69 patients with a total of 74 artificial hips. They looked at patients who had hip problems but were asymptomatic, symptomatic with a known mechanical cause and those patients with unexplained pain. Synovitis was found in the majority of all the patients, but it was only statistically significant in patients suffering adverse local tissue reactions.

“Synovial volume on MRI may be a valuable marker in the longitudinal assessment of asymptomatic patients with a metal-on-metal hip resurfacing and in identifying patients with adverse local tissue reaction,” the researchers concluded.

Concerns About Metal-on-Metal Hip Problems

Concerns have surfaced in recent years that metallic debris from metal-on-metal hip implants could cause tissue damage and metal blood poisoning, also known as metallosis. In many cases, these problems have caused individuals to experience problems where their hip replacement loosens or fails catastrophically and ultimately needs to be replaced.

In January, the FDA released new guidance for metal-on-metal hip replacements. The agency told doctors that metal-on-metal hip replacement systems should only be used if other artificial hip implants were not appropriate, and called on manufacturers to prove that their implants were safe enough to stay on the market. Future metal-on-metal hip designs will have to undergo extensive human clinical trials before being made available for sale, the FDA decreed.

The agency also provided updated information for orthopedic surgeons, advising that doctors should pay close attention to patients with metal-on-metal hip replacements and to look for signs and symptoms of common problems associated with those artificial hips.

Metal-on-Metal Hip Lawsuits

A number of metal-on-metal hips have been recalled, targeted by patients who say they were sold defective artificial hips, or both. In August 2010, Johnson & Johnson issued a recall for the DePuy ASR metal-on-metal hip system, after data suggested that as many as one out of every 8 implants were failing within five years. However, by the time the hip replacement was removed from the market more than 90,000 of the components were sold worldwide.

Johnson & Johnson now faces thousands of DePuy ASR lawsuits. So far this year, two cases have gone to trial, with one case in California resulting in an $8.3 million damage award and a second case in Illinois state courtresulting in a defense verdict.

In addition, a growing number of lawsuits have been filed over other metal-on-metal hip systems, including the DePuy Pinnacle hip, Biomet M2A Magnum hip and Wright Medical Conserve Cup.