Outcome of revision UKR to TKR when compared to a matched group of TKR of same total arthroplasty lifespan.

Aim: To compare outcomes of revision uni-compartmental knee replacement (UKR) with a defined revision cause with a matched group of primary total knee replacements (TKR).

Background: UKR accounts for 8.7% of knee arthroplasty in the UK each year. It has better functional outcome than total knee replacement for isolated single compartment arthritis but can result in complex surgery when revision is required. This is feared to result in poorer patient reported outcomes when compared to primary TKR. We aim to compare the clinical results of revised UKR with primary TKR, taking into account the survival length of the UKR.

Patients And Methods: Forty-five patients (27 female) were retrospectively identified from our arthroplasty database that had undergone revision from UKR to TKR (1999-2014) and had a minimum of two years of follow-up post-revision. These patients were then matched with regards to age at primary procedure, sex, BMI and total arthroplasty life (UKR + Revision TKR) up to point of follow-up.

Results: In the UKR revision group (mean arthroplasty life 8.6 years) the mean Oxford knee score (OKS) was 31.8. In the primary knee group (mean arthroplasty life 8.4 years) the mean OKS was 32.8. This difference was not statistically significant. Fifteen out of 45 patients undergoing revision surgery required stemmed components.

Conclusion: UKR provides comparable clinical outcome even after revision surgery to TKR as primary TKRs and should be considered in all patients meeting the selection criteria. Revision is complex and revision components should be available.