Metal-on-Metal Hip Implant

A metal-on-metal hip implant is a total hip replacement or resurfacing device in which the ball (femoral head) and the cup (acetabular component) are both made of metal, usually a cobalt and chromium alloy. They were promoted as more durable than designs using plastic or ceramic, especially for younger, active patients, and were widely implanted in the 2000s.

The problem is wear. The FDA explains that as the metal ball and cup slide against each other, tiny metal particles wear off, and some metal ions such as cobalt and chromium enter the bloodstream. Over time the particles can damage bone and soft tissue around the joint, a local reaction the FDA calls an adverse local tissue reaction. That damage can cause pain, loosening, device failure, and the need for revision surgery to remove and replace the implant. Some patients also develop symptoms elsewhere in the body.

These problems led to recalls of certain designs and to thousands of product liability lawsuits against manufacturers, which were grouped into multidistrict litigation by product. The lawsuits alleged that companies sold designs that failed far more often than expected and did not warn surgeons and patients. Many were resolved through large settlement programs that paid more to people who needed revision surgery. Claims usually require implant records showing the brand and model, and records of revision surgery or elevated metal ion levels.

If you have a metal-on-metal hip, the FDA recommends follow-up with your surgeon even without symptoms. See the metallosis entry, and our guides on multidistrict litigation and class actions versus mass torts.