DOS 2019

DOS Kongressen 2019 · 179 Which Oxford Knee Score level represents a satisfactory symptom state after undergoing a total knee replacement? Lina Holm Ingelsrud, Kirill Gromov, Berend Terluin, Andrew Price, David Beard, Anders Troelsen Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Department of General Practice and Elderly Care Medicine, VU University Medical Center, Amsterdam, Netherlands; Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, United Kingdom Background: Meaningful interpretation of postoperative Oxford Knee Score (OKS) is challenged due to a lack of knowledge about the patients’ perspectives on the threshold for having a successful or unsuccessful treatment outcome. Purpose / Aim of Study: To determine Patient Acceptable Symptoms State (PASS) and Treatment Failure (TF) values for the OKS in patients undergoing primary total knee replacement (TKR) in Denmark. Materials and Methods: Data from patients undergoing primary TKR between February 2015 and January 2019 were extracted from one hospital’s arthroplasty database. Patients completed the OKS at 3, 12 and 24 months postoperatively, accompanied by two anchor questions asking whether they considered their symptom level to be accept- able (yes/no), and if not, whether their symptom level was so unsatisfactory that they considered the treatment to have failed (yes/no). PASS and TF threshold values were calculated using the predictive modeling method, which is based on logistic regression, with the PASS and TF anchors as dependent variables and postoperative OKS as the in- dependent variable. Non- parametric bootstrapping was used to derive 95% confidence intervals (CI). Findings / Results: Complete data were obtained for 187 out of 209 (89%), 884 out of 915 (97%) and 575 out of 586 (98%) patients at 3, 12 and 24 months postoperatively, with a median age ranging from 68 to 70 years (59 to 64% female). The proportions of patients achieving a PASS were 72%, 77% and 79%, while 6%, 11% and 11% considered the treatment to have failed, at 3, 12 and 24 months postoperatively, respectively. OKS PASS values (95% CI) were 27.13 (25.82; 28.45), 30.18 (29.39; 30.99) and 30.45 (29.37; 31.39) at 3, 12 and 24 months postoperatively. Corresponding TF values were 26.67 (25.48; 27.83) at 12 months, and 27.28 (25.87; 28.63) at 24 months postop- eratively. The absolute number of patients considering TF at 3 months was too low to calculate that TF value. Conclusions: These PASS values, determined with novel methodology, can be used to guide the interpretation of the outcome of TKR, when measured with the OKS. PASS and TF thresholds were very close, suggesting that treatment outcome can be dichotomized into successful and not successful outcome using the PASS values. 135.