Interaction between physical activity and sleep quality at midterm after total knee arthroplasty: a Japanese retrospective cohort study

Purpose: No report has clarified the frequency and interacting factors affecting sleep disturbance among Asian patients at midterm after total knee arthroplasty (TKA). This study aimed to evaluate the frequency of sleep disturbance at midterm after TKA in a Japanese cohort and to identify intervening factors for sleep. We hypothesized that residual knee pain and decreased physical activity negatively interact with sleep quality after TKA. Methods: A total of 209 Japanese participants (average age: 77.1 ± 8.3 years; postoperative follow-up period: 4.5 ± 1.9 years) who underwent primary TKA for knee osteoarthritis were included in this study. Sleep quality, satisfaction, pain, physical activity, joint awareness, and mental condition were evaluated using the Pittsburgh Sleep Quality Index (PSQI), Knee Society Score (KSS) 2011, Forgotten Joint Score (FJS)-12, and 12-Item Short-Form Health Survey (SF-12) Mental Component Summary (MCS). Multivariate analysis was performed to determine the influencing factors on PSQI. Results: The scores for the PSQI, satisfaction with pain level while lying in bed, pain during level walking, functional activity category in the KSS 2011, awareness of the artificial joint in bed at night in the FJS-12, and SF-12 MCS were 6.7 ± 3.0, 5.8 ± 1.8, 1.6 ± 2.3, 62 ± 22, 1.5 ± 1.4, and 56 ± 9.3 on average, respectively. Sleep disturbance (PSQI ≥ 5.5) occurred in 54% of the Japanese participants. Multivariate analysis revealed that high activity was a significant interacting factor for sleep quality improvement (p < .05). Conclusion: Decreased physical activity, not residual knee pain, negatively interacted with sleep quality. The sleep disturbance rate was high during the middle postoperative period after TKA in the Japanese cohort, suggesting that interventions that promote daytime exercises may be effective.