Metal alloys have been used for years in hip resurfacing and total hip replacement procedures. Metal-on-metal hips have been under scrutiny for their high rates of failure, resulting in hundreds of lawsuits aimed at device manufacturers. Combining metal parts with other materials such as ceramic or polyethylene has proven to be subpar as well.
In a recent article published by Medscape, an informative website for physicians and health care professionals, metal-on-polyethylene hip resurfacing procedures showed volumetric polyethylene wear 10 times higher than for standard hip replacements.
Patients who have received metal-on-metal hips, however, have been found with elevated metal ion levels in the urine, metallosis (a condition in which particles from the metal’s wear have made their way into the bloodstream), pseudotumors, and metal hypersensitivity.
The metal used in hip implants is mostly made up of cobalt-chromium alloys. Dr. Steve Tower, an orthopaedic surgeon who specializes in hip, knee and shoulder surgery, was the recipient of a metal-on-metal hip, and began experiencing pain only a year after the replacement surgery. The cobalt levels in his blood were found to be extremely high, and when the pain became unbearable three years after the original surgery, Dr. Tower had to have a revision surgery. That’s when doctors found severe tissue damage surrounding the hip joint.
After the revision, “Within a short period of time, the neurologic issues I had experienced went away,” Tower recalls. “I had placed the same hip in one of my patients, who experienced similar problems.” After the patient underwent revision surgery, the problems went away.
Metal-on-metal hip implant manufacturers such as Wright Medical, DePuy Orthopaedics (a subsidiary of Johnson & Johnson), Stryker, Smith & Nephew and Zimmer Biomet Holdings have been facing a high number of lawsuits alleging injuries linked to the devices.