What question did this study set out to answer?

This study aims to evaluate re-revision rates and outcomes of UKA-to-TKA versus UKA-to-UKA revisions.

May 27, 2026Journal of Experimental Orthopaedics0 citationsOpen Access

Lower re‐revision rates after UKA‐to‐TKA than UKA‐to‐UKA revision for failed medial unicompartmental knee arthroplasty at mid‐term follow‐up

KKKevin‐Arno Koch JFJakob Freytag MHMustafa Hariri

Key Points

This study aims to evaluate re-revision rates and outcomes of UKA-to-TKA versus UKA-to-UKA revisions.
Retrospective single-centre study with 113 aseptic UKA revisions from 2001 to 2020.
Patients were divided into UKA-to-UKA (n=38) and UKA-to-TKA (n=75) groups for comparison.
Re-revision rates and implant survival assessed using Kaplan-Meier analysis and patient-reported outcome measures.
Re-revision rates were 21.1% for UKA-to-UKA and 4.0% for UKA-to-TKA (p=0.003).
10-year implant survival was higher for UKA-to-TKA revisions at 95.3% versus 78.6% for UKA-to-UKA.
Functional outcomes showed no significant differences, but range of motion was greater after UKA-to-UKA revision (126° vs. 114°, p<0.001).

Abstract

Abstract Purpose Revision following unicompartmental knee arthroplasty (UKA) remains challenging, and optimal revision strategy is still debated. This study analysed failure mechanisms after aseptic medial UKA revision and compared mid‐term outcomes between UKA‐to‐UKA and UKA‐to‐total knee arthroplasty (TKA) revision procedures. Methods A retrospective single‐centre study included 113 consecutive aseptic UKA revisions performed between 2001 and 2020. Patients were stratified into UKA‐to‐UKA ( n = 38) and UKA‐to‐TKA ( n = 75) groups. Progression of lateral osteoarthritis (31%) and aseptic loosening (27%) were the most common indications for revision. Re‐revision rates were evaluated and implant survival was assessed using Kaplan–Meier analysis with log‐rank testing and Cox regression. Functional outcomes were evaluated using validated patient‐reported outcome measures (Oxford Knee Score, Knee Society Scores, UCLA activity score, visual analogue scale) and range of motion. Results During follow‐up, re‐revision occurred in 8 of 38 UKA‐to‐UKA revisions (21.1%) and in 3 of 75 UKA‐to‐TKA revisions (4.0%). Re‐revision after UKA‐to‐TKA revision occurred due to suspected early infection ( n = 2) and aseptic loosening ( n = 1), whereas after UKA‐to‐UKA revision the main causes were aseptic loosening ( n = 3), unexplained pain ( n = 3) and bearing dislocation ( n = 2). Overall, 10‐year implant survival was 89.7%. Implant survival at 10 years was higher following UKA‐to‐TKA revision compared with UKA‐to‐UKA revision (95.3% vs. 78.6%; log‐rank p = 0.003). PROMs did not differ significantly between groups, whereas range of motion was greater after UKA‐to‐UKA revision (126° vs. 114°, p < 0.001). Conclusion Conversion of medial UKA to TKA was associated with lower re‐revision rates compared with UKA‐to‐UKA revision, while patient‐reported outcomes were comparable between strategies. UKA‐to‐UKA revision may remain appropriate in selected cases with surgically addressable failure mechanisms. These findings support an individualised revision strategy based on the underlying cause of failure. Level of Evidence Level III, retrospective cohort study.

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