Diabetes mellitus blunts the symptoms, physical function, and health-related quality of life benefits of total knee arthroplasty: A systematic review with meta-analysis of data from more than 17 000 patients

U OBJECTIVE: To compare physical function, pain, impairments (stiffness, range of motion, and strength), and health-related quality of life (HRQoL) outcomes between patients with and without diabetes mellitus, before and after a total knee arthroplasty (TKA). U DESIGN: Prognosis systematic review. U LITERATURE SEARCH: We searched MEDLINE/PubMed, CINAHL, SPORTDiscus, and Web of Science to August 2019. U STUDY SELECTION CRITERIA: We included longitudinal studies that examined physical function, pain, impairments, and HRQoL outcomes among patients receiving a TKA and with or without diabetes. U DATA SYNTHESIS: For quantitative synthesis, we stratified outcomes based on time relative to TKA: preoperative, less than 1 year after a TKA (early postoperative), and 1 year or more after a TKA (late postoperative). We used random-effects meta-analysis to calculate standardized mean differences (SMDs) and 95% confidence intervals (CIs). We used the Grading of Recommendations Assessment, Development and Evaluation system for qualitative synthesis. U RESULTS: We included 21 studies (n = 17 472 patients). Patients with diabetes mellitus had worse preoperative physical function (SMD, -0.16; 95% CI: -0.24, -0.08) and HRQoL (SMD, -0.16; 95% CI: -0.26, -0.05), worse early postoperative pain (SMD, -0.22; 95% CI: -0.39, -0.05) and strength (SMD, -0.45; 95% CI: -0.77, -0.14), and worse late postoperative physical function (SMD, -0.23; 95% CI: -0.40, -0.06), range of motion (SMD, -0.23; 95% CI: -0.46, 0.00), and HRQoL (SMD, -0.19; 95% CI: -0.29, -0.08) than patients without diabetes mellitus. The overall risk of bias across studies was high, and the certainty of evidence ranged from low to very low. U CONCLUSION: Patients with diabetes mellitus had worse patient-reported and clinician-assessed outcomes before and after a TKA. Given the limitations of included studies, these results may change with future research.