In a study at Coxa Hospital for Joint Replacement in Finland, researchers assessed 176 patients who received metal-on-metal hip implants (203 hips) and found that 84 of those hips required revision surgery. In 87 percent of these revisions, adverse soft-tissue reaction to metal debris (ARMD) was diagnosed. Additionally, a larger femoral diameter and stem type had a higher risk of ARMD, metallosis, and device failure.
Metal-on-metal hip designs, made by a number of medical device manufacturers such as Wright Medical, DePuy Orthopaedics and its parent company Johnson & Johnson, Stryker, Smith & Nephew and Zimmer Biomet Holdings, are made up of a cobalt-chromium alloy, which has been known to shed metal debris with normal use.
The hips, which use a metal ball and metal socket design, were originally intended to be a more durable, longer-lasting hip for younger patients, or for patients who have a more active lifestyle. However, the hip has been found to fail in as little as two to five years, while other hips made of ceramic or plastic parts can last 20 years or more.
When metal ions from the debris leach into the blood stream, cobalt and chromium toxicity can occur, which is linked to symptoms such as high blood pressure, dizziness and skin rashes, tremor, poor coordination, cognitive decline and depression as well as damaging effects on the heart, hearing and vision.
Metal-on-metal hip implant manufacturers are facing thousands of lawsuits alleging the devices have resulted in suffering of recipients. DePuy Orthopaedics, a subsidiary of Johnson & Johnson, is facing 8,900 lawsuits in the U.S. alone over the allegedly faulty hip designs.