title: Validation of a prediction model that allows direct comparison of the Oxford Knee Score and American Knee Society clinical rating system.
abstract: This study demonstrates a significant correlation between the American Knee Society (AKS) Clinical Rating System and the Oxford Knee Score (OKS) and provides a validated prediction tool to estimate score conversion. A total of 1022 patients were prospectively clinically assessed five years after TKR and completed AKS assessments and an OKS questionnaire. Multivariate regression analysis demonstrated significant correlations between OKS and the AKS knee and function scores but a stronger correlation (r = 0.68, p < 0.001) when using the sum of the AKS knee and function scores. Addition of body mass index and age (other statistically significant predictors of OKS) to the algorithm did not significantly increase the predictive value. The simple regression model was used to predict the OKS in a group of 236 patients who were clinically assessed nine to ten years after TKR using the AKS system. The predicted OKS was compared with actual OKS in the second group. Intra-class correlation demonstrated excellent reliability (r = 0.81, 95% confidence intervals 0.75 to 0.85) for the combined knee and function score when used to predict OKS. Our findings will facilitate comparison of outcome data from studies and registries using either the OKS or the AKS scores and may also be of value for those undertaking meta-analyses and systematic reviews.
authors.affiliation: Victoria Hospital, Hayfield Road, Kirkcaldy KY2 5AH, UK.
authors.forename: J F
authors.initials: JF
authors.lastname: Maempel
authors.affiliation: Victoria Hospital, Hayfield Road, Kirkcaldy KY2 5AH, UK.
authors.forename: N D
authors.initials: ND
authors.lastname: Clement
authors.affiliation: Victoria Hospital, Hayfield Road, Kirkcaldy KY2 5AH, UK.
authors.forename: I J
authors.initials: IJ
authors.lastname: Brenkel
authors.affiliation: Victoria Hospital, Hayfield Road, Kirkcaldy KY2 5AH, UK.
authors.forename: P J
authors.initials: PJ
authors.lastname: Walmsley
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee; D005260:Female; D005500:Follow-Up Studies; D006305:Health Status Indicators; D006801:Humans; D007717:Knee / Q000601:surgery*; D007719:Knee Joint / Q000601:surgery*; D008297:Male; D008962:Models, Theoretical; D020370:Osteoarthritis, Knee / Q000601:surgery*; D011446:Prospective Studies; D015203:Reproducibility of Results; D016896:Treatment Outcome
keywords: American knee society patient reported outcome; Oxford knee score; Total knee arthroplasty