Recently, I had a total hip arthroplasty on my right hip. I picked the orthopaedic surgeon to perform my total hip and allowed him to pick the implant, especially since his results (which I scoped out) were so good. I ended up with a femoral head of oxidized zirconium and a highly cross-linked polyethylene liner—don’t ask me, I don’t know; all I know is that it hasn’t gotten the same kind of press that metal-on-metal (MoM) hip replacements have gotten lately.
I do know one thing as a patient who has now received two total hips: immediately after surgery, they hurt, “block” or “no block.” Doctors never seem to tell patients about this. Wow, what pain occurred when I tried (monkey bars and all) to get out of bed for the first time! I believe as a rite of passage, every orthopaedic resident should have a total hip or total knee replacement before graduating so he or she will know pain and have empathy for patients.
Total joint arthroplasty, I believe, ranks in the top four or five greatest medical advances—along with antibiotics, anesthesia, and magnetic resonance imaging—and certainly is the greatest advance in orthopaedics during my career. Now the MoM controversy has emerged and threatens to undermine patient confidence in hip arthroplasty, orthopaedic surgeons, and device oversight.
There are those who believe that the use of stemmed large-diameter MoM primary total hip replacements should be stopped, that these devices should no longer be used until all the questions about the various adverse local tissue reactions (ALTRs) such as pseudotumors are resolved.
Others believe that the problem has been exaggerated and overblown and that the complication rate is device-dependent. As noted in a recent article in The Journal of Bone and Joint Surgery–American, some patients with ALTRs readily visible on CT scans are asymptomatic.
As orthopaedic surgeons, we all know that well-designed and implanted devices in the right patients perform well and generally have acceptable complication rates. So what is the answer to the MoM total hip replacement controversy? I don’t know, especially since I don’t do total joint arthroplasty.
What about resurfacing procedures that showed so much promise in younger patients? Although the British Hip Society recommended that its members stop using stemmed large-diameter MoM primary total hip replacement, it also specifically stated that this prohibition does not apply to resurfacing procedures. This may be good because at the moment, there does not appear to be any other choice for resurfacing except MoM bearing surfaces.
So where am I going with this? I think we need answers to some questions, including the following:
- What is the cause of the ALTR phenomena?
- How should the orthopaedic surgeons in the United States respond to the British Hip Society’s recommendation to stop using stemmed large-diameter MoM primary total hip replacements?
- What is the optimum follow-up protocol for those who already have a MoM hip?
- What is the status of the hip resurfacing procedures in terms of patient selection and optimum follow-up?
These questions need to be answered—and answered quickly—by a knowledgeable, authoritative group of orthopaedists and recommendations put forward.
The AAOS has already issued technology overviews on hip resurfacing and MoM hip implants. They’re not great reading, but they ought to be read by every surgeon who performs these procedures. Both the AAOS, on its patient information website orthoinfo.org, and the U.S. Food and Drug Administration (FDA) have comprehensive information for patients that would also be of interest to surgeons.
Historically, but not often in orthopaedics, we have been “bitten” in hindsight by procedures such as chymopapain and faulty implants and allograft materials that in retrospect we should have avoided. But in these cases, we had no knowledge of the detrimental effects preoperatively. With stemmed large-diameter MoM primary total hip replacements, I believe we have been warned.
Let’s get some actionable information through (1) joint registries (this is a great example of why the United States desperately needs a registry), (2) a consensus-based algorithm from the AAOS and the specialty societies focused on joint replacement, outlining how patients with MoM hip replacements should be evaluated and managed, and (3) continued surveillance by the FDA and other international regulatory bodies.
The FDA has also asked industry to conduct postmarket surveillance studies to measure the outcomes and assess the safety of MoM implants. And at the end of June, the FDA will hear from an expert advisory panel on the risks and benefits of MoM implants—and you can be sure that the AAOS will be part of that meeting.
Until some definitive word is released, however, both patients and surgeons need to clearly understand the potential risks and benefits of MoM hip systems.
Oops, I’m sure there’s lots more I could say about this if I had more time and more knowledge, but here comes my physical therapy guy to get me up on my new hip! I just hope it doesn’t squeak!