A research team from Brigham and Women’s Hospital in Boston, Massachusetts, has won the 2022 James A. Rand Young Investigator’s Award from the American Association of Hip and Knee Surgeons (AAHKS).
The work, to be published in a special issue of the Journal of Arthroplasty dedicated to AAHKS Annual Meeting, highlights increased revision risk with rotating platform bearings in total knee arthroplasty (TKA).
Lead author Vishal Hegde, M.D., assistant professor of Orthopaedic Surgery at The Johns Hopkins University in Baltimore, Maryland, along with fellow researchers and co-authors, Jamil Kendall, M.D., Kathryn Schabel, M.D., Christopher E. Pelt, M.D., Patrick J. Yep, M.P.H., Kyle Mullen, M.P.H., Ayushmita De, Ph.D. and senior author Ryland Kagan, M.D., compared and contrasted rotating platform revision risks to fixed bearing knee implant revision risks.
The team collected data from 485,024 TKAs of which 452,199 (93.2%) were fixed bearing implants and 32,825 (6.8%) were rotating platform bearing implants.
When the team set up a head-to-head comparison of the two design platforms, they found that rotating platform patients were at increased risk for all-cause revision when compared to fixed bearing implants.
There were, the team found, no differences between the two designs in terms of infection triggered revisions. They did find an increased risk for all-cause revision for rotating platform bearings across all time points, with a greater magnitude of risk as time elapsed out to eight years.
“Although this study demonstrated a small absolute clinical difference between rotating platform and fixed bearing total knee arthroplasties, this difference was still significant. We hope that these findings will help inform orthopedic surgeons about the potential risks when they elect to use a rotating platform design for their patients,” said Dr. Hegde.
Unsurprisingly, More Work to be Done
Responding to OTW’s question, “What is it about the tibial component design that poses a problem?” Dr. Hegde explained, “At this point we do not know what it is about the design of rotating platform bearings that is leading to the increased risk of revision.”
“All this study tells us is that there is a difference in survivorship: it is up to us to focus further study on finding out what the cause is of this difference in survival, be it the design of the tibial component, complications due to bearing dislocation, or some other issue that we may have not yet discovered.”
As for what can be done about the risk of bearing dislocation, he added, “In my opinion, the risk of bearing dislocation is a function of a poorly balanced knee. If the knee is balanced appropriately, it is unlikely there will be sufficient laxity to allow for dislocation of the bearing.”
“Orthopedic surgeons using rotating platform bearings should pay particular attention to the balance of the knee throughout the arc of motion to ensure appropriate tension is present. In addition, it remains unclear if this is an issue that is unique to the level of constraint of the total knee design—further study is required to see if the risk of revision is similar for both cruciate retaining and posterior stabilized total knees utilizing a rotating platform bearing.”
