Rotating platform implants are intended to reduce polyethylene wear and improve patellar tracking in total knee arthroplasty (TKA) as a result of axial freedom. However, the associated tibial component design, added complexity with balance, and the risk of bearing dislocation have raised concerns among surgeons for increased risk of revision when these implants are used.
Is that concern justified?
It may be, according to a study presented at the 2022 annual meeting of the American Association of Hip and Knee Surgeons (AAHKS). But more research is needed to determine why rotating platform implants are more likely to be revised than fixed-bearing implants, the investigators said.
This study received the AAHKS James A. Rand, MD, Young Investigator’s Award at the association’s annual meeting. This award recognizes young investigators who demonstrate clinical excellence in knee-related research.
For the study, the researchers used data from the American Joint Replacement Registry, which was linked to data from the Centers for Medicare and Medicaid Services, on patients aged 65 and older who underwent TKA between 2012 and 2019. Of the more than 485,000 TKA patients they identified, the majority received fixed-bearing implants (n=452,199; 93.2%) compared with rotating platform implants (n=32,825; 6.8%).
The researchers found that patients who had received a rotating platform implant were at increased risk for all-cause revision compared with patients who received a fixed-bearing implant. (P< 0.0001). This was true across all time points, with the risk increasing with time. No difference was observed between groups for revision for infection (P=0.516).
The increased risk for all-cause revision with rotating platform implants echoes the findings of other national registry investigations.
“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 orthopaedic surgeons about the potential risks when they elect to use a rotating platform design for their patients,” said lead author Vishal Hegde, MD.
The researchers concluded that with infection ruled out as a cause of increased revision with rotating platform implants, “additional investigation is needed to determine if the increased failure rates could be related to unaccounted for patient selection factors, surgical technique, bearing issues, or potentially implant-related issues including tibial baseplate fixation.”
Hegde V, Kendall JS, Schabel KL, Pelt CE, Yep PJ, Mullen K, De A, Kagan RP. Increased revision risk with rotating platform bearings in total knee arthroplasty. Presented at the annual meeting of the American Association of Hip and Knee Surgeons, November 3-6, 2022, Dallas, Texas.