Ban on Metal-on-Metal Hips Urged (Walter Eisner @ OTW)
Surgeons should stop using metal-on-metal (MoM) hip replacements.
That’s the conclusion of a study published on March 13 in the journal Lancet and paid for by the National Joint Registry of England and Wales, the largest joint registry in the world.
An analysis of 400,000 hip replacements between 2003 and 2011 showed that about 6% of patients with MoM hips needed revision surgery after five years. Patients with ceramic or plastic joints only needed 1.7 to 2.3% revision surgery. The rate was particularly high with larger-head implants and those used in women, in whom failure rates were up to four times higher, the researchers said. Of the 400,000 hip surgeries studied, more than 31,000 were MoM. The analysis did not cover resurfacing systems, which avoid the use of a stem sticking into the bone, such as Smith & Nephew’s Birmingham Hip Resurfacing joints.
Metal-on-metal hips were developed to be more durable than traditional implants, which combine a ceramic or metal ball with a plastic socket.
Earlier in the month, the British version of the FDA, the Medicines and Healthcare Products Regulatory Agency (MHRA), warned that patients with MoM hips should get yearly blood tests to check for metals seeping into their bodies. The MHRA decided, however, against a ban on use, arguing that stemmed MoM implants could still be good news for some patients.
One of the study’s authors, Ashley Blom, head of orthopedic research at the University of Bristol, noted that most people with MoM hips haven’t needed revisions. But, he said, with alternatives available, there was no reason to take the risks.
Blom said,
If I were a patient, I would not choose a metal-on-metal hip.
Major manufacturers of MoM hips include, DePuy Orthopaedics, Inc., Smith & Nephew plc, Zimmer Holdings, Inc., Stryker Corporation, Biomet, Inc., Wright Medical Technology, Inc. and Corin Group plc.
DePuy recalled its MoM version, the ASR, in 2010 and the FDA asked manufacturers to conduct safety studies in 2012. According to the study, use of the devices has dropped dramatically in recent years worldwide. In the UK, only about 5% of patients are believed to be getting the metal hips. In the U.S., estimates are about 500,000 people have them.
The results, said the researchers, were unequivocal: “Metal-on-metal stemmed articulations give poor implant survival compared with other options and should not be implanted.”
We’ll report on the responses to the registry study from manufacturers, the American Academy of Orthopaedics Surgeons and the FDA as we get them. Stay tuned.