Revision of unicompartmental knee replacement can achieve equivalent outcomes to primary total knee replacement when revised for confirmed pathology.

Abstract

There is conflicting evidence regarding outcomes following revision of Unicompartmental Knee Replacement (UKR) to Total Knee Replacement (TKR). We hypothesise that a UKR can be successfully revised to a TKR with equivalent outcomes to primary TKR when revised for a well-defined revision diagnosis such as progression of arthritis. From 2011 to 2023, the records of a surgeon were reviewed to identify patients who underwent revision of a UKR. Data collected included indications for revision, implant details, oxford knee scores (OKS) and survivorship. The OKS of the revision group was compared with a group of primary TKRs. A total of 21 revision UKR to TKR were included in the study. Primary Cruciate Retaining implants were used in all but 1 revision (Posterior Stabilised) with tibial sided augments or a stem required in 4. Survivorship of the revision UKRs was 95.2% at a mean of 4.37 years post-operatively. Mean OKS for the group was 37.65 with an improvement of 19.65 (p = 0.0001). Patients revised for a well-defined indication had 6-month mean OKS of 41.29, comparable to the primary TKR mean OKS of 39.5 (p = 0.535). Patients revised without confirmed pathology had mean 6-month OKS of 29.17 which was significantly worse than the remaining revision UKRs and primary TKRs (p = 0.001). When a UKR is revised for a well-defined revision indication, patients can expect equivalent outcomes to primary TKR. This study also confirms that in most instances, a UKR can be successfully revised utilising primary implants with good midterm survivorship.