Medical Devices

Why surgeons are partly to blame for failing metal-on-metal hip implants

The controversy over metal-on-metal hip implants has ensnared 21 companies that have been required by the U.S. Food and Drug Administration to do post-market studies into whether their implants shed high levels of metal debris into patients’ bloodstreams.

But orthopedic surgeons have played a role in the metal-on-metal controversy, too, according to a report from patient safety group the ECRI Institute.

Part of the implants’ failure rate can be blamed on doctors who used them in the wrong types of patients, said a physician quoted in the report, Dr. Javad Parvizi, a professor of orthopedic surgery with Thomas Jefferson University Hospital in Philadelphia.

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“Metal-on-metal did have promise for a very small population,” Parvizi said. “For extremely heavy males who were very active, it was a great option compared to all of the other bearing surface options.”

The problem is doctors prescribed metal-on-metal implants to a much wider population than they should have, figuring their bigger femoral head diameter was more likely to reduce the likelihood of postoperative dislocation, according to Parvizi.

“Surgeons utilized them much more commonly and because of that we are paying a price,” he said.

Researchers know that metal-on-metal bearing surfaces generate metal particles in the blood, but what they don’t know is exactly what effect that has on patients, according to Parvizi. “Metal-on-metal technology for the most part would be very difficult to bring back,” he said.

Another orthopedic surgeon — Dr. Michael Berend, of Franciscan St. Francis Health’s Center for Hip & Knee Surgery in Mooresville, Indiana — cautioned against lumping all metal-on-metal hip implants together.

His medical practice has implanted more than 1,200 patients with Biomet’s M2a Magnum metal-on-metal hip implants and has had “an excellent early track record.”

“There are significant differences in manufacturing, in tolerances, in design … in the components, and in the way they’re implanted,” he said. “Not all metal-on-metal implants are created equal.”

[Photo from nih.gov]

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