Prevalence and Predictors of Symptom Resolution and Functional Restoration in the Index Knee After Knee Arthroplasty: A Longitudinal Study

Objectives To determine the prevalence of a 1- to 2-year postsurgical pain-free state and pain plus symptom-free state as well as functional restoration after knee arthroplasty (KA) and to identify predictors of these outcomes. Design Cohort study. Setting Communities of 4 sites. Participants Consecutive participants (N=383) who underwent KA on at least 1 knee during the first 8 years of the study (mean age, 67.95±8.5y; 61.4% women; n=235). Interventions Not applicable. Main Outcome Measures A composite pain score included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain scale and 2 generic pain rating scales. Composite pain plus other symptoms scores included 3 pain scales, a stiffness scale, and, in addition, the Knee injury and Osteoarthritis Outcome Score Symptoms scale. The WOMAC Function scale was used to quantify functional status. Prevalence estimates and predictors of a pain-free state, symptom-free state, and a fully functioning state were determined. Results A sample of 383 participants with KA was studied, and of these, 34.1% (95% confidence interval [CI], 29.3%–39.2%; n=131) had a composite score of 0 for pain. A total of 14.1% (95% CI, 10.8%–18.1%; n=54) had a composite score of 0, indicating a symptom-free state, whereas 29.0% (95% CI, 24.4%–34.0%; n=111) achieved a score of 0 on the WOMAC Function scale. Conclusions The prevalence of complete pain relief was 34%, the prevalence of complete pain and symptom relief was 14%, and the prevalence of complete functional restoration was 29% after KA. Participants who are older and with lower (better) WOMAC Pain scores were more likely to be pain-free after surgery. These data collected from a community-based sample have the potential to inform clinicians screening patients for KA consultation in a shared decision-making discussion to better align patient expectations with the most likely outcome.