Midterm-Adjusted Survival Comparing the Best Performing Unicompartmental and Total Knee Arthroplasties in a Registry.

BACKGROUND: Recent literature suggests that the difference in revision risk between unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) can be influenced by surgeon volume and other confounders. We hypothesized that implant selection might decrease the relative risk of revision in an adjusted model.

METHODS: We selected the best performing (BP) primary UKAs and TKAs performed for osteoarthritis between January 2001 and December 2012 collected through a joint replacement registry. We compared aseptic and all-cause risk of revision using a surgeon-stratified Cox regression model with propensity score adjustment.

RESULTS: One thousand fifty-four UKAs were compared with 74,185 TKAs. The rate for all-cause revision was lower for UKAs (2.1%) than for TKAs (2.4%), whereas the rate for aseptic revision was higher for UKAs (2.0%) than TKAs (1.4%). The adjusted risk of aseptic revision was not significantly higher for UKA than TKA (hazard ratio = 2.02 [0.68, 5.96], P = .203) or all-cause revision (hazard ratio = 1.24 [0.52, 2.98], P = .603).

CONCLUSION: When comparing the survivorship of the BP UKAs to the BP TKAs in our registry, the adjusted risk of revision remained higher for UKAs than for TKAs, although the difference did not reach statistical significance.