There is not much hard evidence that new artificial joint devices, including ceramic-on-ceramic bearings for hip replacement and high flexion knee replacement, are better than older options - and in some cases they may be worse - according to a new review.
Senior author Dr. Art Sedrakyan and his team reviewed clinical trials, comparative studies and registries for evidence that five new implantable device innovations were effective and safe.
Similar research published in 2011 led to manufacturers withdrawing some metal-on-metal hip replacement options, which turned out to have higher failure rates than others because the metal parts rubbing together created debris that could lead to inflammation and tissue damage.
“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,” said 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 is ‘no’ because the procedure is generally very safe and outcomes are generally good,” he said.
However, new product designs tend to be based on engineering data more than on clinical data, he said. It seems, logically, like a new design may have an advantage over the old, but that often isn’t supported by evidence with real patients, he said.
Sedrakyan and his team looked for evidence supporting five recently introduced and well-known hip and knee devices, including ceramic-on-ceramic bearings, modular femoral necks and uncemented monoblock cups for total hip replacement, as well as high-flexion knee replacement and gender-specific knee replacement.
All these technologies are already “implemented” in patients, the authors write in the journal BMJ.
The 118 studies comparing outcomes with these devices versus older options were of varying quality and few were high-quality randomized trials, the study team found.
None of the five devices appeared to improve functioning or survival more than the older versions. And some of them had up to twice the rate of needing replacement in a subsequent “revision” surgery compared to existing options.
Registries showed modular femoral necks were revised 1.9 times as often as predecessor technologies, and ceramic-on-ceramic hip bearings and high-flexion knee bearings were also replaced more often, according to the results.
None of the newer devices appeared to have poor enough outcomes that their use should necessarily be discontinued, Sedrakyan said, but there was generally a lack of evidence in their favor.
“The technologies that are supposed to be better are not proving to be better and some which are widely used happen to be worse,” Sedrakyan said.
The data show that not all new orthopedic devices are being studied carefully, and when they are being studied, the studies themselves may be limited in quality, said Dr. Aaron S. Kesselheim of Brigham and Women’s Hospital in Boston who co-authored an editorial on the topic in BMJ.
Older implants may not always be safer, but since they have been around longer and used in more patients it’s easier for safety issues to come to light, he said.
“Of course, that issue would only emerge if someone’s looking for it, and unfortunately, safety data on implants are not systematically collected all the time,” Kesselheim said in an email.
Hospital administrators usually choose and purchase the devices that end up inside patients, he said. But patients can have a voice, and should ask their surgeons if the device slated for their surgery has been proven effective and safe, not just that it is widely used or popular with some patients, Sedrakyan said.
Many patients do not know to ask this question, and the implant itself may be decided on at the time of surgery, Kesselheim said.
“Stakeholders like surgeons, regulators and patients need to work together to demand a different and improved system of surveillance of these new products,” Sedrakyan said.