PROMs in total knee replacement: analysis of negative outcomes.

INTRODUCTION: NHS England uses the Oxford Knee Score (OKS) as part of patient-reported outcome measures (PROMs) to evaluate 'health gains' following total knee replacement. Policy makers use this to guide healthcare funding and resource allocation. Our study aims to undertake a qualitative and quantitative analysis of OKS among patients who experienced a negative outcome after a total knee replacement at our centre. MATERIALS AND METHODS: Between April 2017-March 2018, 19 of 189 (10%) patients had a worsened OKS at our centre. We retrospectively and prospectively reviewed 14 of these patients. Structured telephone interviews with a repeat OKS were carried out in September 2019 (18-29 months post-operation). RESULTS: Eight patients were female and the total age range was 57-95, mean average 75.6 (SD 9.9 years). Of 48 (higher scores meaning better outcomes), the average preoperative OKS was 24.2 and the average postoperative OKS at 6 months was 19.4 (decrease of 20%). The average postoperative OKS at 18-29 months was 35.6 (an increase of 83.5% from 6 months). DISCUSSION: The OKS was developed and validated over 20 years ago in Oxford. In our study, four patients asked for clarification of questions 4, 6 and 10 owing to ambiguous language. All 14 patients who had negative OKS outcomes had positive outcomes when retested after 18 months, depicting 'health gains' not conveyed in PROMs analysis. CONCLUSION: The OKS needs to be revalidated on current patient groups for accurate and reliable data. Further prospective studies should be undertaken on larger cohorts to understand the recovery course and whether PROMs should be carried out later.