An Oxford knee score cut-off point to identify patients with chronic pain after knee replacement for a complex intervention trial

About 20% of patients who undergo primary total knee replacement (TKR) surgery in the UK experience chronic pain after their operation. The provision of healthcare services for these patients has been found to be patchy and inconsistent in the NHS. Although chronic pain is understood to be pain persisting for several months, the level that pain must persist for a patient to be considered in chronic pain is not defined. The aim of this work was to identify a cut-off point in the pain component subscale of the Oxford Knee Score (OKS) that could be used to identify patients in chronic pain following a primary TKR