Daytime variation on clinical outcomes in elderly after total joint arthroplasty under general anaesthesia：a prospective study

Background: The circadian rhythm influences various physiological processes, affecting health outcomes significantly. This study aims to explore the impact of daytime variation on outcomes following total joint arthroplasty, specifically focusing on the recovery of independent walking ability. Materials and Methods: Between May 2023 and May 2024, we prospectively evaluated 530 consecutive patients undergoing total joint arthroplasty. Daytime variation was categorized into morning (7:30 a.m. to 12:00 p.m.) and afternoon (12:00 p.m. to 6:00 p.m.) based on anesthesia records. Functional recovery, defined as the ability to independently walk across a room 30 days post-surgery, was assessed via telephone interviews. Multivariate logistic regression analyzed factors influencing functional recovery. Results: Of 362 patients, 177 (48.9%) underwent morning surgeries and 185 (51.1%) underwent afternoon surgeries. Before adjustment, a higher proportion of patients in the afternoon surgery group achieved functional recovery compared to the morning group (71.9% vs. 54.8%). After adjusting for potential confounders, patients undergoing morning surgeries were less likely to regain independent walking ability compared to those undergoing afternoon surgeries (adjusted odds ratio [aOR], 1.94; 95% CI, 1.18 to 3.20; P=0.009). Incidences of postoperative delirium (aOR, 0.50; 95% CI, 0.29 to 0.88; P=0.015) and postoperative sleep disturbances (aOR, 0.49; 95% CI, 0.32 to 0.77; P=0.002) within the first 7 days were lower in the afternoon surgery group. Multivariable regression analysis, afternoon surgery was found to be statistically associated with increased odds of functional recovery (aOR: 1.75; 95% CI, 1.03 to 2.97; P=0.039). No significant differences were observed in other clinical outcomes. Conclusion: Daytime variation appears to significantly influence outcomes following total joint arthroplasty, particularly in achieving independent walking ability at 30 days postoperatively. Clinical trial number: not applicable.