A large series (Hamadouche et al., Clin Orthop Relat Res, 2016), looked at over 2,000 revisions of both metal-polyethylene and ceramic-on-ceramic. The mean time to revision on the ceramic-ceramic cohort was approximately three years. And the reasons for revision are exactly the same—ceramic breakage, squeaking, and implant mal-seating.
Despite the newer generation of ceramics, increased awareness of the importance of implant positioning, fractures and squeaking still occur.
If metal-on-metal and ceramic-on-ceramic are out, what’s my alternative for the young patient?
Crosslinked polyethylene with the latest updated data (Bragdon et al., 2016). Thirteen year follow-up, 264 hips, a mix of both 32mm and 36mm, as well as some ceramic heads, and the wear rates of 0.002mm/year—that’s a lot of zeroes—increased wear rate with larger heads at 0.035mm/year and no reported incidences of osteolysis.
This has led me to conclude that ceramics are extremely sensitive to implant position.
Despite the newer implants that are out there, we still have an incidence of fracture, squeaking and impingement. With crosslinked polyethylene the wear rates are almost zero, there’s no observable osteolysis. Larger heads have not compromised performance. And, I’d say, that the current use of ceramic-on-polyethylene mitigates the trunnion issue. And the use of crosslinked polyethylene gets the advantage of a ceramic head without the concerns of a ceramic-ceramic bearing.
So I’d like to conclude that plastics are the future and the future is now.
Moderator Thornhill: That’s great. Dr. Lee, you said that squeaking rate was very low and Doug said it was 7.5%. That’s high. Can you reconcile that difference of opinion?
Dr. Lee: Yeah, I think it depends on how you ask the question and what you truly define as squeaking. I think if you poll all your total hip patients –conventional bearings versus ceramic-on-ceramic hips—and ask whether their hips make noise, a large proportion of them will say that their hips make noises that are inaudible to anybody else.
If you define true squeaking as somebody that walks down the hallway and you can hear squeaking, that incidence is probably less than 7.5%. If you basically poll for whether their articulation makes noise clicking or snapping, that incidence may be higher.
Moderator Thornhill: So you’re saying that much of that is insignificant squeaking.
Dr. Lee: Correct.
Dr. Padgett: We looked at our original alumina-alumina series that we published and squeaking incidence was about 9%. Chit reported noises of any incidences as high as almost 20%. I would agree that almost all articulations can generate some noise, although I’ve never actually observed any ceramic- or metal-on-polyethylene squeaking. If you’re one of those patients that has squeaking you are not happy.
Moderator Thornhill: What is the cost differential between…I know it varies from institution to institution…but what is the cost differential?
Dr. Lee: It varies. At our institution a ceramic-on-ceramic hip is about $1,000 more compared to a conventional bearing hip replacement.
Moderator Thornhill: There’s always been concern about ceramic debris in terms of its bio-reactivity. If you have a fracture or some chipping, does ceramic debris concern you?
Dr. Lee: Ceramic debris does concern me if it fractures. That’s why there’s a specific way to revise a broken ceramic. With a broken ceramic liner or head you have to do a wide exposure, complete debridement, make sure as much of the debris is out and you want to put a ceramic ball head back in because they’re more scratch resistant and harder. You don’t want to use a metal ball head since they could be scratched up.
Moderator Thornhill: Doug, your wonderful biomechanics expert, Tim Wright, has talked about crosslinked polyethylenes in the loaded areas leeching out some of the antioxidants in the weight bearing areas and their crosslinking goes down, right? Is that a long-term problem?
Dr. Padgett: I don’t think we know the answer to that. I can tell you that the data that we’ve got now is 13-15 year data and it looks very impressive. I would be somewhat cautious about the introduction of second and third generations to solve a theoretical problem as it relates to oxidation of the polymer.
Moderator Thornhill: I’d like to thank the speakers. They both did a great job and stayed on time and on top of it.
Please visit www.CCJR.com to register for the 2018 CCJR Spring Meeting, – May 20 – 23 in Las Vegas.
Senior Editor: Jay D. Mabrey, M.D., whose 35 year career in orthopedics included residency at Duke University Medical Center, service in the United States Army Medical Corps, Fellowship at the Hospital for Special Surgery and a long, distinguished career at Baylor University Medical Center where, in addition to his overall leadership at that institution, developed the Joint Wellness Program that helped patients get up after surgery more quickly, developed the first virtual reality surgical simulator for knee arthroscopy and chaired the FDA Orthopaedic Device Panel, is Orthopedics This Week’s newest contributing writer and editor.
I”m following a metal on metal total ankle design now 15 years post op, ball-and-socket configuration. Patient continues to do well, very satisfied. Since THRs gave m-on-m a bad name am seeking the only other hard on hard material, that being your ceramic-on-ceramic. Any interest in discussing this further?
I'”m following a metal on metal total ankle design now 15 years post op, ball-and-socket configuration. Patient continues to do well, very satisfied. Since THRs gave m-on-m a bad name am seeking the only other hard on hard material, that being your ceramic-on-ceramic. Any interest in discussing this further?