The Bell Law Firm, PLLC

When medical device manufacturers introduced metal-on-metal hip replacement implants, they hoped the new materials would make the implants more durable than earlier models. A recent study shows that not to be the case. It turns out that the implants fail at a higher rate than their predecessors.

The device replaces the hip's ball-and-socket structure and can be made of metal, ceramic, plastic or a combination of materials. The metal-on-metal model was meant to replace the metal-on-plastic model, which was thought to be less durable. The study, however, discovered that more patients with replacements made entirely of metal needed repeat surgery -- in fact, metal-on-metal patients were twice as likely to need the follow-up surgery.

Patients reported more problems than tripping airport security. They complained of pain, swelling and joint dislocation; some even reported systemic damage from toxic levels of metal ions.

In an effort to close the barn door after the horses have bolted, federal safety regulators have asked metal-on-metal device manufacturers for more information on defects or health risks associated with the replacements. The authors of the study agree that more detailed analysis is appropriate, but they add that it's unlikely additional data will change the overall message -- that is, that these devices fail at a higher rate.

The researchers looked at 18 studies that, all told, involved more than 3,000 patients and more than 830,000 operations. In the U.S., hip replacements account for 270,000 of the 700,000 joint replacement performed every year.

The study also showed that the metal-on-metal devices didn't improve outcomes for the patients. In categories like ability to carry out daily activities, there was no difference between the older models and the newer metal-on-metal models.

The authors recommend that anyone whose doctor suggests a metal-on-metal implant ask why that model is preferred.

Source: Reuters.com, "New report highlights metal hip implant problems," Toni Clarke, Nov. 30, 2011