Overview: Although the two-day U.S. Food and Drug Administration (FDA) advisory panel meeting last week was not able to provide conclusions to some of the more pressing questions over metal-on-metal hips, the group of experts did agree that use of the devices should be limited.
- Last week, the FDA’s Orthopaedic and Rehabilitation Devices Panel held a two-day meeting to discuss the safety of metal-on-metal hips
- The panel recommends that symptomatic patients undergo blood screening for metal ions and imaging for tissue damage; they said that the FDA should give a reference range for what qualifies as safe or unsafe levels of cobalt and chromium
- While it is clear that some metal replacements can shed metallic debris, the panel did not attribute the problem to any one cause
Manufacturer & Product
|Johnson & Johnson/ DePuy Orthopaedics||Biomet||Smith & Nephew||Zimmer||Wright Medical Technology|
|ASR (recalled)||M2a Magnum||Oxinium||Durom||CONSERVE Hip Systems|
Side Effects & Complications
- High failure rate
- Necrosis (tissue death)
- Increased levels of cobalt and chromium ions
- Pain at the implant, sometimes spreading to the groin and back
- Osteolysis (bone loss)
- Fluid collections/solid masses around the hip joint
When metal-on-metal hips were first introduced, it was thought that they would be a better alternative for younger, more physically active patients. As many patients have found, however, the implants can shed tiny pieces of metal that seep into the bloodstream and affect local tissue. According to the British Medical Journal (BMJ) however, the panel was unwilling to attribute the elevated metal ion issue to any one cause, nor did they call an end to their use.
The panel would not ban the devices. However, they did think that the use of metal-on-metal hip replacements should be limited, partially due to the fact that poly-based implants have been showing improvement over the years. But since data was not presented about those devices, they would not make any comparisons. Raj Rao, from the Medical College of Wisconsin, points out that “In the absence of comparative data, I think it is difficult for this panel to make definitive conclusions.” according to BMJ.
The panel recommended blood screening for metal ion levels and imaging techniques such as X-rays, MRIs and CT scans to check for tissue damage, but only for patients who are symptomatic. They also said that the FDA should provide guidelines for what qualifies as safe, intermediate or unsafe levels of chromium or cobalt. The panelists also pushed for the FDA to provide information about the devices, and possibly issue more warnings.
Regulatory Action Elsewhere
While the FDA has yet to issue specific recommendations, other countries have taken a more cautious route. In the UK, the Medicines Healthcare products and Regulatory Agency (MHRA) has provided continual guidelines for patients with metal-on-metal hip replacements. The agency has advised yearly blood tests and imaging for all symptomatic patients.