FDA Requests Post-Market Data for Metal-on-Metal Hip Implants

The U.S. Food and Drug Administration (FDA) is requesting post-market studies of metal-on-metal hip implant patients from 21 device makers, including Johnson & Johnson, Biomet Inc., Stryker Corp. and Zimmer Holdings, among others.

The future of metal-on-metal implants was debated at the annual meeting of the American Academy of Orthopaedic Surgeons last February. At the time, the FDA said it was “actively working in several areas to further assess the safety and effectiveness” of the devices. It was also recommended that surgeons avoid all-metal implants in patients with afflictions such as suppressed immune systems or known metal sensitivity. The FDA further encouraged patients with all-metal hips to address their surgeons immediately regarding new or significantly worsening pain, swelling, numbness or walking issues.

“The priority of an orthopaedic surgeon is a patient’s safety and postoperative quality of life,” the President of the American Academy of Orthopaedic Surgeons (AAOS), Daniel J. Berry, M.D. told Orthopedic Design & Technolgy. “The AAOS is supportive of ongoing, clinical research to determine how devices perform and will continue to collaborate with the FDA.”

To assist the FDA in expansion of its review, the requested device makers must submit a research protocol that addresses safety issues related to the devices, including higher-than-expected rates of replacement surgery, increased risk of tissue necrosis surrounding the implants and increased levels of metals, particularly cobalt and chromium, in the bloodstream.

The request comes nine months after J&J subsidiary DePuy Orthopedics, Inc. voluntarily recalled its ASR XL Acetabular System due to an unusually high rate of repeat procedures.

It remains to be seen how the latest request will affect existing criticism of the 510(k) approval process.

Currently, the FDA requires manufacturers to disclose the wear particle size, shape distribution and concentration development during biomechanical testing; manufacturers must demonstrate that the particles produced are not of bioactive size range and are of low concentration.

In an emailed statement, FDA spokeswoman Karen Riley said that the FDA “is aware of the public health questions regarding the safety of metal-on-metal total hip replacement systems…there is not enough scientific data to specify the concentration of metal ions in a patient’s body necessary to produce adverse systemic effects.”

The FDA also said that a decision on the “proper classification of metal-on-metal hip systems is forthcoming but is unrelated to the post-market surveillance order.”