When Dr. Art Sedrakyan and fellow researchers published the first paper on premature failures of metal-on-metal hip replacement systems in 2011, several medical device manufacturers responded by withdrawing their all-metal hip implants. It turned out the failures were caused when the metal parts rubbed against each other, causing metal bits to inflame neighboring tissue and leech into the bloodstream poisoning the blood.
“Back in 2011 when we published the first paper on metal-on-metal hips, hundreds of people contacted me and asked if they should be worried about hip replacement in general,” says Sedrakyan, of the Patient Centered Comparative Effectiveness Program and U.S. Food and Drug Administration Medical Device Epidemiology Science and Infrastructure Center at Weill Cornell Medical College in New York.
The answer, he said, is no. However, this led to an investigation into newer hip and knee product designs, which Sedrakyan says in some cases may be worse than older models.
Newer product designs tend to be based on engineering data rather than clinical data, he says. While this may give good information on how the device functions, it doesn’t necessarily stand up to good, hard evidence supplied by patients themselves.
Sedrakyan and his team investigated five recently introduced and well-known hip and knee devices, which included ceramic-on-ceramic devices, modular femoral necks and uncemented monoblock cups for total hip replacement, high-flexion knee replacement and gender-specific knee replacement. All the implants had been used in patients.
Researchers found that none of the devices appeared to improve functioning or survival more than older models. Some even had as much as twice the failure rate as a previous device. However, the rates were not so bad as to warrant a recall, he said.
While the type of device used is often determined by hospital administrators, patients do have a voice and are encouraged to talk with surgeons about the device that will be used in their surgery.
“Stakeholders like surgeons, regulators and patients need to work together to demand a different and improved system of surveillance of these new products,” Sedrakyan says.