Abstract
BACKGROUND: The goal of this study was to investigate the association between preoperative radiographic severity of knee osteoarthritis (OA) and patient-reported outcomes following total knee replacement. METHODS: We used data from a prospective cohort study of individuals who underwent total knee replacement at a high-volume medical center. Patient-reported outcomes included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain score and the Knee injury and Osteoarthritis Outcome Score (KOOS) activities of daily living (ADL) subscore, assessed preoperatively and 2 years postoperatively. We measured preoperative radiographic OA severity using the Osteoarthritis Research Society International (OARSI) Atlas score, dichotomized at the median. We assessed the association between radiographic OA severity and postoperative patient-reported outcomes in bivariate analyses and in multivariable linear regression, with adjustment for age, sex, body mass index, and comorbidity score. RESULTS: The analytic cohort included 240 patients with a mean age at surgery of 66.6 years (standard deviation, 8 years); 61% were female. The median total OARSI radiographic severity score was 10 (range, 3 to 17). The cohort improved substantially at 2 years following total knee replacement, with WOMAC pain and KOOS ADL score improvements on the order of 30 points. We did not observe significant or clinically important differences in pain relief or functional improvement between patients with milder and more severe radiographic OA. Sensitivity analyses using other radiographic assessment measures yielded similar findings. CONCLUSIONS: Total knee replacement offers substantial symptomatic relief and functional improvement regardless of preoperative radiographic OA severity. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.