Preoperative symptom burden in the knee replacement population - the role of the Oxford knee score

The Oxford Knee Score (OKS) represents a validated Patient Reported Outcome Score (PROM), routinely utilised following knee replacement (TKR). Healthcare commissioners have proposed its application as a threshold criterion to define eligibility for TKR, despite an absence of supporting evidence. This thesis explores the role of preoperative OKS, using local and national PROMs data, as a measure of symptom burden and highlights potential issues as a threshold criterion tool. Examination of the preoperative OKS profile in three orthopaedic centres showed a normal distribution profile, and wide-ranging preoperative symptom burden. Some patients appeared to proceed to TKR with a seemingly minimal symptom burden, raising question about TKR selection criteria. Further analysis of national PROMs data confirmed wide variability in preoperative symptom burden prior to TKR to be common practice. Some variation existed between centres and individual surgeons, but patient level factors were a greater contributor, suggesting poor selection criteria may not be to blame. Case note analysis of a TKR cohort from a single centre identified that those with a high preoperative OKS still exhibited a significant symptom burden, remaining clinically justified for TKR. An appropriate consultation process was evident, rejecting inappropriate selection criteria as an explanation. Analysis of linked national pre- and postoperative OKS data showed that patients with highest preoperative OKS had best overall outcomes following TKR, despite minimal change in OKS. Preoperative OKS<16 was associated with worse outcomes and minimal further benefit as OKS decreased. Preoperative OKS alone may not encapsulate the true clinical indications for TKR. Utilisation of OKS-based thresholds, may exclude equally eligible patients, risking greater inequity and variation in TKR practice. Restricting TKR to those with the worst preoperative OKS may compromise subsequent outcomes. Its role as an indicator of preoperative symptom burden and potential eligibility for TKR should be used with extreme caution.