How do patients sleep after orthopedic surgery? Changes in objective sleep parameters and pain in hospitalized patients undergoing hip and knee arthroplasty

<strong>Aim.</strong> Sleep impairment after hip and knee arthroplasty is multifactorial and still poorly understood and post-operative pain is a potential cause of sleep deprivation or disturbances. The aim of this study was to assess actigraphy-based sleep characteristics and pain scores in patients undergoing knee or hip joint replacement and hospitalized for ten days after surgery. <strong>Methods.</strong> In this observational cohort study, n=20 subjects (11 males and 9 females; age: 64.0±10.39 years old) completed a daily sleep diary and wore the Actiwatch 2 actigraph (Philips Respironics, Portland, OR) to record sleep parameters for 11 consecutive days, starting the day before surgery and ending the 10^th day after surgery. Subjective scores of pain, by a visual analog scale (VAS), were constantly monitored for the entire experimental protocol. The following evaluation time-points have been considered for the analysis: pre-surgery (PRE), the first (POST1), the fourth (POST4) and the tenth day (POST10) after surgery. A repeated-measures one-way analysis of variance followed by the Tukey-Kramer post hoc tests, or the equivalent nonparametric Friedman test followed by the Dunn’s multiple comparisons, was applied to test differences in sleep and pain among time-points. Test for correlation between mean VAS score and the sleep parameters at each post-operative time point were performed using Pearson’s method. <strong>Results.</strong> Sleep quantity and timing parameters did not differ from PRE to POST10, during the hospitalization. On the contrary, Sleep Efficiency (p=0.006; η²_p=0.45, large), Sleep Latency (p=0.039; η²_p=0.37, large), Wake After Sleep Onset (p=0.042; η²_p=0.34, large), Immobility Time (p=0.005; η²_p=0.47, large) and Fragmentation Index (p=0.016; η²_p=0.36, large) displayed significant differences. In detail, Sleep Efficiency and Immobility Time significantly decreased at POST1 compared to PRE by 10.8% (p=0.003; ES: 0.9, moderate) and 9.4% (p=0.005; ES: 0.86, moderate) respectively. Overall, all sleep quality parameters showed a trend of constant improvement from POST1 to POST10. VAS scores were higher in the 1^st day post-surgery (4.58 ± 2.46; p=0.0011 and ES: 1.40, large) compared to POST10 (1.68 ± 1.58) and in POST4 (3.85 ± 2.31) compared to POST10 (-2.18; p=0.0087 and ES: 1.09, moderate). During time, mean VAS showed significant negative correlations with mean Sleep Efficiency (r = -0.71; p=0.021) and mean Immobility Time (r = - 0.83; p=0.003) and a significant positive correlation with Fragmentation Index (r = 0.70; p=0.023), highlighting that high scores of pain were associated with lower overall sleep quality. <strong>Conclusion.</strong> Sleep quantity and timing parameters were stable during the entire hospitalization whereas sleep quality parameters significantly worsened the 1^st night after surgery compared to the pre-surgery night and, overall, these parameters showed a trend of constant improvement until discharge. Pain scores were at the highest level the 1^st day after surgery and at the lowest level before discharge with a negative correlation between pain and sleep quality parameters during time. The present study confirms the important impact of surgery on sleep parameters, especially on the first few post-operative days.**目的** 髋膝关节成形术（arthroplasty）后睡眠障碍的发生机制呈多因素性，目前仍未被充分阐明；而术后疼痛是引发睡眠剥夺或睡眠紊乱的潜在诱因。本研究旨在纳入接受膝/髋关节成形术且术后住院时长为10天的患者，评估基于活动记录仪（actigraphy）的睡眠特征与疼痛评分情况。 **方法** 本研究为观察性队列研究，共纳入20名受试者（男性11名，女性9名；年龄64.0±10.39岁）。所有受试者均填写每日睡眠日志，并佩戴Actiwatch 2活动记录仪（飞利浦Respironics，美国俄勒冈州波特兰市）连续11天记录睡眠参数，记录周期始于术前1天，止于术后第10天。本研究采用视觉模拟评分法（Visual Analog Scale, VAS）对受试者的主观疼痛评分进行全程持续监测。本研究选取以下四个时间点开展数据分析：术前（PRE）、术后第1天（POST1）、术后第4天（POST4）及术后第10天（POST10）。采用重复测量单因素方差分析（repeated-measures one-way analysis of variance）结合Tukey-Kramer事后检验（Tukey-Kramer post hoc tests），或等效的非参数Friedman检验（Friedman test）结合Dunn多重比较（Dunn’s multiple comparisons），以检验不同时间点间睡眠与疼痛指标的组间差异。采用皮尔逊相关分析（Pearson’s method），检验各术后时间点的平均VAS评分与睡眠参数间的相关性。 **结果** 住院期间，睡眠总量与睡眠时序参数在术前至术后第10天期间未出现显著组间差异。与之相反，睡眠效率（Sleep Efficiency）、睡眠潜伏期（Sleep Latency）、睡眠后觉醒时间（Wake After Sleep Onset）、活动不能时间（Immobility Time）及睡眠碎片化指数（Fragmentation Index）均呈现出显著组间差异（p=0.006; η²p=0.45，大效应量；p=0.039; η²p=0.37，大效应量；p=0.042; η²p=0.34，大效应量；p=0.005; η²p=0.47，大效应量；p=0.016; η²p=0.36，大效应量）。具体而言，与术前相比，术后第1天的睡眠效率与活动不能时间分别显著下降了10.8%（p=0.003; 效应量ES=0.9，中等效应）与9.4%（p=0.005; 效应量ES=0.86，中等效应）。整体而言，所有睡眠质量参数均呈现出从术后第1天到术后第10天逐步改善的趋势。术后第1天的VAS评分为4.58±2.46，显著高于术后第10天的1.68±1.58（p=0.0011; 效应量ES=1.40，大效应量）；术后第4天的VAS评分为3.85±2.31，显著高于术后第10天，平均差值为2.18（p=0.0087; 效应量ES=1.09，中等效应）。随着时间推移，平均VAS评分与平均睡眠效率（r=-0.71; p=0.021）及平均活动不能时间（r=-0.83; p=0.003）呈显著负相关，与睡眠碎片化指数（r=0.70; p=0.023）呈显著正相关，表明较高的疼痛评分与较差的整体睡眠质量密切相关。 **结论** 住院期间，睡眠总量与睡眠时序参数始终保持稳定；而睡眠质量参数在术后第1晚较术前晚出现显著恶化，且整体呈现出直至出院前持续改善的趋势。疼痛评分在术后第1天达到峰值，于出院前降至最低，且随着时间推移，疼痛与睡眠质量参数呈显著负相关。本研究证实了手术对睡眠参数的显著影响，尤其是在术后最初几日。