Diagnostic study, Level II.

While more unicompartmental knee implants than total knee implants were revised for unexplained pain, when these revisions for unexplained pain were discounted, unicompartmental knee arthroplasty still had a significantly greater risk of revision from other reasons than did total knee arthroplasty. The revision rate in isolation may not be a reliable way to compare different implant designs and should instead be considered in the context of the reason for failure.

Following arthroplasty of the knee, the patient's perception of improvement in symptoms is fundamental to the assessment of outcome. Better clinical outcome may offset the inferior survival observed for some types of implant. By examining linked National Joint Registry (NJR) and patient-reported outcome measures (PROMs) data, we aimed to compare PROMs collected at a minimum of six months post-operatively for total (TKR: n = 23,393) and unicondylar knee replacements (UKR: n = 505). Improvements in knee-specific (Oxford knee score, OKS) and generic (EuroQol, EQ-5D) scores were compared and adjusted for case-mix differences using multiple regression. Whereas the improvements in the OKS and EQ-5D were significantly greater for TKR than for UKR, once adjustments were made for case-mix differences and pre-operative score, the improvements in the two scores were not significantly different. The adjusted mean differences in the improvement of OKS and EQ-5D were 0.0 (95% confidence interval (CI) -0.9 to 0.9; p = 0.96) and 0.009 (95% CI -0.034 to 0.015; p = 0.37), respectively. We found no difference in the improvement of either knee-specific or general health outcomes between TKR and UKR in a large cohort of registry patients. With concerns about significantly higher revision rates for UKR observed in worldwide registries, we question the widespread use of an arthroplasty that does not confer a significant benefit in clinical outcome.

This study found no demonstrable benefit of single-stage compared to two-stage revision for the infected total knee replacement using a variety of PROMs. Thus, we recommend that decision making must be based on other factors such as re-infection rate.

The Exeter femoral stem continues to perform well beyond 20 years. Cite this article: Bone Joint J 2016;98-B:1441-9.