Metal-on-Metal Hip Implant Pain Linked to Tissue Damage, Study Shows

American Academy of Orthopaedic Surgeons

Unexplained pain in patients with metal-on-metal (MoM) implants is more often an indication of tissue damage rather than implant wear, according to researchers from the Hospital for Special Surgery (HSS). Dr. Danyal Nawabi and his colleagues from HSS presented their findings in Chicago during the annual meeting of the American Academy of Orthopaedic Surgeons (AAOS) that took place March 19-23.

Hip replacement surgery helps hundreds of thousands of patients each year regain mobility and relieve osteoarthritis pain. However, the HSS has seen a rise in patients presenting with unexplained hip pain after being implanted with metal-on-metal hips, and around the country thousands of patients filed lawsuits against manufacturers of these implants, claiming the implants are defective.

Researchers conducted the study to determine the cause of the pain in patients with metal-on-metal implants who came to HSS for revision surgery – about 10 percent of the hospital’s 9,000 annual hip replacement surgeries are revisions.

The results revealed more than half of the study participants had “moderate to high adverse tissue reactions.”

Early Identification of Pain Can Avoid Damage

Dr. Timothy Wright, Kirby Chair of Orthopedic Biomechanics at HSS, said: “We found that some patients had a significant amount of tissue damage but not a lot of wear, suggesting that factors other than wear are contributing to the problem regardless of whether the patients have pain.”

Lead researcher Douglas Padgett added that patients with metal-on-metal hips should be followed closely by their surgeons and that “early identification of patients with unexplained pain is vital to avoid significant tissue damage.”

This is not the first study to reveal evidence of tissue damage caused by metal debris from MoM implants. Based on its own studies, the FDA released a 2013 safety communication warning that tissue damage resulting from excessive metal debris released by these implants can lead to revision surgery.

Tissue damage has already led to thousands of lawsuits filed by people who suffered from complications from certain brands of metal-on-metal hips, such as the DePuy ASR and Stryker Rejuvenate and ABG II because of metal debris.

Aside from metal-on-metal implants, however, several benefits of hip replacements were also discussed at the annual meeting.

Research Points to Benefits of Hip Replacement

From reducing the risk of heart failure, depression and diabetes to improving patients’ sex lives, other studies presented at the AAOS meeting focused on the benefits of total hip replacement.

Results of other studies presented at the meeting include:

  • People with osteoarthritis who had a total hip replacement had lower mortality risk and reduced risk of heart failure, diabetes and depression than those who did not.
  • 98 percent of people who received a total knee replacement were able to return to work and regular life following surgery.
  • MRIs can detect potential failures of metal-on-metal hips early on.
  • 90 percent of people who received total knee or hip replacements reported improvement in sexual function.

Another study highlighted that hip and knee replacement surgery affects overall improvement in activity and quality of life. Anne Lübbeke-Wolff, a Swiss orthopaedic surgeon and lead study author, told Science Daily: “Surgery substantially and durably improved physical activity levels in men and women of all age categories, but the level remained somewhat lower than just before the onset of osteoarthritis symptoms.”

Doctors at the Hospital for Special Surgery said they intend to use the results from their studies to compose new guidelines for patients.