At least all-metal hip implants haven't caused cancer (yet)

Metal-on-metal hip implants are being blamed for a host of health and mechanical problems. But in a small bit of good news, they don't appear to cause cancer 7 years after implantation, according to new data evaluated by the UK National Joint Registry (NJR). In other words: so far, so good.

Still, as Reuters reports, the NJR couches its conclusion with a note of caution, reminding us that many cancers can take far longer to develop.

"Many cancers have prolonged latency after initial exposure to carcinogens and thus long-term follow-up is needed to provide a definitive answer," the NJR noted in its annual report, as cited by Reuters.

All-metal hip implants may increase the risk of melanoma, blood, prostate and renal tract cancers, according to some initial studies cited by the NJR and noted in the article. They have been shown to have higher failure rates and cause a host of safety and health problems. The growing health concern forced Johnson & Johnson ($JNJ)/DePuy and Stryker ($SYK) to recall a number of models as a result, and they've continued to face a legion of liability lawsuits. And regulators around the world have increased their scrutiny. In the U.S., for example, the FDA wants J&J, Stryker, Zimmer and 17 other devicemakers to conduct additional studies and determine whether their hip implants hike the level of metal in patients' blood to dangerous levels. Over the summer, an FDA panel of experts recommended avoiding all-metal implants because of the risks involved.

The NJR used hospital statistics from the National Health Service (NHS) for its analysis, Reuters explains. They compared metal-on-metal implants to other surfaces, like metal-on-polyethylene, to see whether the all-metal variety boosted cancer risks in the initial years after a hip replacement procedure.

- read the Reuters story