According to a study published in January in BMC Psychiatry, an online journal of psychiatric disorders, cobalt and chromium toxicity from metal-on-metal hip implant failure resulted in neuropsychiatric complications after revision surgery.
Metal-on-metal hip implants are designed using a metal ball and metal socket made of a cobalt-chromium alloy. When the parts rub together during normal use, the parts may shed metal ions, which can pollute the bloodstream and damage the surrounding tissue.
The normal range occurring in a person’s system due to normal environmental exposure is 0–20 nmol/l for cobalt and 0–100 nmol/l for chromium. Nine of the 10 patients in this study were found to have toxic cobalt and chromium blood levels, at around a mean 669.4 nmol/l for cobalt and a mean 338 nmol/l for chromium. Short-term memory deficit was evident in 7 of 9 patients, scoring a mean 24.2 in the mini mental state examination (less than 25 usually indicates possible dementia).
One patient, referred to as “Mrs. A” in the study, had an ASR total hip replacement at age 50. Five years later, Mrs. A required revision surgery. At the time of the revision surgery, her chromium levels registered at 664 nmol/l and cobalt levels of 2470 nmol/l. Her symptoms included chronic pain, low mood, low self confidence, poor sleep, decreased appetite, and severe forgetfulness. She could no longer efficiently recall previous conversations and began withdrawing from social activities. She had trouble concentrating, and by the age of 57, had cognitive abnormalities with a mini mental state examination score of 18.
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.
Source: BMC Psychiatry