There is no clinically important difference in the Oxford knee scores between one and two years after total knee arthroplasty: The one-year score could be used as the benchmark timepoint to assess outcome ☆ N.D. Clement a,b,c, ⁎, I. Afzal c , C. Demetriou c , David J. Deehan a , R.E. Field c , D. Kader c a Department of Orthopaedics, Freeman Hospital, Newcastle, UK b Department of Orthopaedics, Royal Infirmary of Edinburgh, Edinburgh, UK c South West of London Orthopaedic Elective Centre, Epson, UK article info Article history: Received 17 December 2019 Received in revised form 5 May 2020 Accepted 26 May 2020 Background: The aim was to assess the whether there was a clinically important change in the Oxford knee score (OKS) between one and two years after total knee arthroplasty (TKA), and to identify predictors associated with a clinically important change. Methods: A retrospective cohort study was undertaken using an established arthroplasty data- base of 5857 primary TKA. Patient demographics, body mass index, social deprivation, OKS and EuroQoL five-domain (EQ-5D) score were collected preoperatively and at one and two years postoperatively. A clinically important change in the OKS was defined as ≥ 5 points. Results: There was a 0.2 point increase in the OKS between one and two years, which was sta- tistically significant (95% confidence interval (CI) 0.1 to 0.4, p b .0001), but not clinically impor- tant. A better preoperative OKS (p b .001) and in contrast a worse one year OKS (p b .001) were independently associated with a greater improvement from one to two years. There were 1006 (17.3%) patients that had a clinically important improvement in the OKS between one and two years. Receiver operating characteristic curve analysis showed that a one year OKS of less than 35 was a reliable predictor of a clinically important improvement between one and two years (area under the curve 0.77, 95% CI 0.76 to 0.78, p b .001). Conclusion: There was not a clinically important change in the OKS from one to two years after TKA when assessed as a group. However, individual patients with a one year OKS of less than 35 may demonstrate a clinically important improvement at two years. Level of evidence: Retrospective diagnostic study, Level III. © 2020 Elsevier B.V. All rights reserved. Keywords: Change Difference Follow-up Total knee arthroplasty Outcome Oxford knee score The Knee 27 (2020) 1212–1218 ☆ Study centre: The South West of London Orthopaedic Elective Centre, Epson, UK. ⁎ Corresponding author at: Department of Orthopaedics, Freeman Hospital, Freeman Road, High Heaton, Newcastle upon Tyne NE7 7DDm UK. E-mail address: nickclement@doctors.org.uk. (N.D. Clement). https://doi.org/10.1016/j.knee.2020.05.015 0968-0160/© 2020 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect The Knee