Categorization of changes in the Oxford Knee Score after total knee replacement: an interpretive tool developed from a data set of 46,094 replacements

Objectives The objective of the study was to create an interpretive categorical classification for the transition in the Oxford Knee Score (OKS) change score (ΔOKS) using the anchor-based method. Study Design and Setting Registry data from 46,094 total knee replacements from the year 2014/15, were accessed via the Health and Social Care Information Center official website. Data included preoperative and 6-month follow-up OKS and response to the transition anchor question. Categories were determined using Gaussian approximation probability and k-fold cross-validation. Results Four categories were identified with the corresponding ΔOKS intervals: “1. much better” (≥16), “2. a little better” (7–15), “3. about the same” (1–6), and “4. much worse” (≤0) based on the anchor questions’ original five categories. The mean 10-fold cross-validation error was 0.35 OKS points (95% confidence interval 0.12 to 0.63). Sensitivity ranged from 0.34 to 0.68; specificity ranged from 0.74 to 0.95. Conclusion We have categorized the change score into a clinically meaningful classification. We argue it should be an addition to the continuous OKS outcome to contextualize the results in a way more applicable to the shared decision-making process and for interpreting research results

Which Oxford Knee Score level represents a satisfactory symptom state after undergoing a total knee replacement?

Background and purpose — Meaningful interpretation of postoperative Oxford Knee Score (OKS) levels is challenging. We established Patient Acceptable Symptoms State (PASS) and Treatment Failure (TF) values for the OKS in patients undergoing primary total knee replacement (TKR) in Denmark. Patients and methods — Data from patients undergoing primary TKR between February 2015 and January 2019 was extracted from the arthroplasty registry at the Copenhagen University Hospital, Hvidovre in Denmark. Data included 3, 12, and 24 months postoperative responses to the OKS and 2 anchor questions asking whether they considered their symptom state to be satisfactory, and if not, whether they considered the treatment to have failed. PASS and TF threshold values were calculated using the adjusted predictive modeling method. Non-parametric bootstrapping was used to derive 95% confidence intervals (CI). Results — Complete 3, 12, and 24 months postoperative data was obtained for 187 of 209 (89%), 884 of 915 (97%), and 575 of 586 (98%) patients, with median ages from 68 to 70 years (59 to 64% female). 72%, 77%, and 79% considered as having satisfactory symptoms, while 6%, 11%, and 11% considered the treatment to have failed, at 3, 12, and 24 months postoperatively, respectively. OKS PASS values (CI) were 27 (26–28), 30 (29–31), and 30 (29–31) at 3, 12, and 24 months postoperatively. TF values were 27 (26–28) and 27 (26–29) at 12 and 24 months postoperatively. Interpretation — The OKS PASS values can be used to guide the interpretation of TKR outcome and support quality assessment in institutional and national registries

Interpretation threshold values for the Oxford Knee Score in patients undergoing unicompartmental knee arthroplasty

Background and purpose: Developing meaningful thresholds for the Oxford Knee Score (OKS) advances its clinical use. We determined the minimal important change (MIC), patient acceptable symptom state (PASS), and treatment failure (TF) values as meaningful thresholds for the OKS at 3-, 12-, and 24-month follow-up in patients undergoing unicompartmental knee arthroplasty (UKA). Patients and methods: This is a cohort study with data from patients undergoing UKA collected at a hospital in Denmark between February 2016 and September 2021. The OKS was completed preoperatively and at 3, 12, and 24 months postoperatively. Interpretation threshold values were calculated with the anchor-based adjusted predictive modeling method. Non-parametric bootstrapping was used to derive 95% confidence intervals (CI). Results: Complete 3-, 12-, and 24-month postoperative data was obtained for 331 of 423 (78%), 340 of 479 (71%), and 235 of 338 (70%) patients, median age of 68–69 years (58–59% females). Adjusted OKS MIC values were 4.7 (CI 3.3–6.0), 7.1 (CI 5.2–8.6), and 5.4 (CI 3.4– 7.3), adjusted OKS PASS values were 28.9 (CI 27.6–30.3), 32.7 (CI 31.5–33.9), and 31.3 (CI 29.1–33.3), and adjusted OKS TF values were 24.4 (CI 20.7–27.4), 29.3 (CI 27.3–31.1), and 28.5 (CI 26.0–30.5) at 3, 12, and 24 months postoperatively, respectively. All values statistically significantly increased from 3 to 12 months but not from 12 to 24 months. Interpretation: The UKA-specific measurement properties and clinical thresholds for the OKS can improve the interpretation of UKA outcome and assist quality assessment in institutional and national registries

Pre-operative SARS-CoV-2 PCR test at between 48 and 72hours pre-operatively is safe for patients undergoing primary and revision hip and knee arthroplasty – a multicentre international study

Introduction: Patients undergoing lower limb arthroplasty who are SARS-CoV-2 positive at the time of surgery have a high-risk of mortality. The National Institute for Health and Clinical Care Excellence and the British Orthopaedic Association advise self-isolation for 14-days pre-operatively in patients at high-risk of adverse outcomes due to COVID-19. The aim of the study is to assess whether pre-operative PCR for SARS-CoV-2 could be performed at between 48 and-72 hours pre-operatively with specific advice about minimising the risk of SARS-CoV-2 restricted to between PCR and admission. Methods: A multi-centre, international, observational cohort study of 1000 lower limb arthroplasty cases was performed. The dual primary outcomes were thirty-day conversion to SARS-CoV-2 positive and thirty-day SARS-CoV-2 mortality. Secondary outcomes included thirty-day SARS-CoV-2 morbidity. Results: Of the 1000 cases, 935 (94%) had a PCR between 48 and 72-hours pre-operatively. All cases were admitted to, and had surgery through a COVID-free pathway. Primary knee arthroplasty was performed in 41% of cases, primary hip arthroplasty in 40%, revision knee arthroplasty in 11% and revision hip arthroplasty in 9%. Six-percent of operations were emergency operations. No cases of SARS-CoV-2 were identified within the first thirty-days. Conclusion: Pre-operative SARS-CoV-2 PCR test between 48 and 72-hours pre-operatively with advice about minimising the risk of SARS-CoV-2 restricted to between PCR and admission in conjunction with a COVID-free pathway is safe for patients undergoing primary and revision hip and knee arthroplasty. Pre-operative SARS-CoV-2 PCR test alone may be safe but further, adequately powered studies are required. This information is important for shared decision making with patients during the current pandemic.</p

Disease modification in OA — will we ever get there?

No drugs are currently approved that change the natural course of osteoarthritis (OA) and translate to long-term, clinically relevant benefits. Two-stage clinical trial designs for OA have now received FDA approval, but remaining challenges lie in defining suitable study populations, surrogate outcomes and pivotal long-term, clinically relevant trial endpoints