The Journal of Arthroplasty 31 (2016) 330–332
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Prospective Evaluation of Sleep Disturbances After Total Knee Arthroplasty Antonia F. Chen, MD/MBA, Fabio R. Orozco, MD, Luke S. Austin, MD, Zachary D. Post, MD, Carl A. Deirmengian, MD, Alvin C. Ong, MD The Rothman Institute, Philadelphia, Pennsylvania
a r t i c l e
i n f o
Article history: Received 18 February 2015 Accepted 31 July 2015 Keywords: total knee arthroplasty sleep pain narcotics knee osteoarthritis
a b s t r a c t Sleep disturbance after total knee arthroplasty (TKA) has not been studied 6 months after surgery. A prospective study was conducted on 34 primary, unilateral TKA patients preoperatively until 6 months postoperatively. Sleep quality was measured using the Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale. Pain was measured on a visual analog scale. Sleep quality worsened from baseline during the first 6 weeks postoperatively (P = .03), but improved at 3 and 6 months (P = .003). Pain scores decreased from baseline over all time points, and there was no correlation between sleep quality and pain. The Epworth Sleepiness Scale did not change over time. This study can be used to counsel TKA patients to expect initial sleep disturbances that improve by 3 months. © 2016 Elsevier Inc. All rights reserved.
Symptomatic knee osteoarthritis (OA) is a condition that affects more than 37.5% of the adults in the United States [1]. These patients experience a worsening in their quality of life and a decreased ability to perform activities of daily living [2]. Studies have also reported that patients with OA have decreased sleep quality, in association with increased night pain, which correlates with radiographic severity of disease [3-6]. To improve patients' lives, the most common surgical treatment for knee OA is total knee arthroplasty (TKA). Studies have demonstrated that performing TKA can improve patients' health-related quality of life and that these levels mostly return to those of the general population [7,8]. Other clinical outcomes, such as Short Form 36, Knee Society Score, and Western Ontario and McMaster Osteoarthritis Index, also improve after TKA [9-11]. However, studies reporting on the changes of sleep quality after TKA have had variable results. A previous study conducted on 110 TKAs found that sleep disruptions 1 month after surgery were associated with increased pain during the same period and limited function 3 months postoperatively [12]. A study involving 10 subjects undergoing fast-track hip and knee arthroplasty demonstrated that rapid eye movement sleep was significantly decreased on the night after surgery but returned to preadmission levels on the fourth postoperative night [13]. One study demonstrated that within 1 month after surgery, patients who undergo
One or more of the authors of this paper have disclosed potential or pertinent conflicts of interest, which may include receipt of payment, either direct or indirect, institutional support, or association with an entity in the biomedical field which may be perceived to have potential conflict of interest with this work. For full disclosure statements refer to http://dx.doi.org/10.1016/j.arth.2015.07.044. Reprint requests: Alvin Ong, MD, 2500 English Creek Ave, Building 1300, Egg Harbor Township, NJ 08234. http://dx.doi.org/10.1016/j.arth.2015.07.044 0883-5403/© 2016 Elsevier Inc. All rights reserved.
TKA have worse sleep quality compared to controls [14]. However, another study demonstrated that there were less sleep disturbances 3 months after TKA and that sleep quality improved by that time [15]. Despite these observations, factors associated with sleep disturbances among patients undergoing elective TKA 6 months after surgery remain unknown. The purposes of this study are to prospectively evaluate preoperative and postoperative sleep disturbance in patients undergoing TKA and to identify risk factors associated with sleep disturbance in TKA patients.
Methods and Materials A prospective cohort study on primary TKA patients was conducted from June 2012 to January 2013. Patients were included if they were undergoing elective primary TKA, were older than 18 years, and were willing and able to complete pre and postoperative surveys. Exclusion criteria included a history of substance abuse, workman's compensation patients, revision TKA patients, patients pending current litigation, history of prescription or supplemental sleeping aids, or patients who did not consent to fill out questionnaires. Only 34 patients were included in the study, as they agreed to fill out the questionnaires associated with this study on a regular basis (baseline, 4 weeks, 6 weeks, 3 months, and 6 months). There were 510 patients who declined to participate in the study during the study period because they did not want to fill out the assessments; however, their demographics were similar to the study population. Institutional review board approval was obtained, and all patients signed a written consent before participating in our study. All patients underwent primary TKA using the midvastus approach under spinal anesthesia, and intraoperatively, all patients received
A.F. Chen et al. / The Journal of Arthroplasty 31 (2016) 330–332
10 mg/kg of intravenous tranexamic acid, intravenous decadron, intravenous ondansteron, and a pericapsular injection consisting of 266 mg bupivacaine liposome injectable suspension (Exparel), 30 mg ketorolac, 150 mg bupivacaine with epinephrine, and 20 mL and saline. Primary TKA was performed by 2 arthroplasty surgeons using the same implants and same postoperative rehabilitation protocols. All patients ambulated on the day of surgery with supervised physical therapy. Patients received the following pain medications during the postoperative hospital period including oxycodone extended release 10 mg by mouth once in postoperative anesthesia care unit, intravenous ketorolac, and oral acetaminophen. No patients were given prescription or supplemental sleeping aids in the postoperative period. Patients were discharged an average of 2.1 days after surgery (range, 1.0-7.0) and were discharged with oxycodone or hydrocodone-acetaminophen. The presence of sleep disturbances was evaluated by 2 separate assessments. First, sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) [16], a self-rated questionnaire that assesses sleep quality and disturbances over a 1-month time interval. Nineteen individual items generate 7 “component” scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. The sum of scores for these 7 components yields 1 global score, with a maximum score of 21. A higher score indicates worse sleep dysfunction, and a score greater than 5 indicates poor sleep quality. All patients were asked to fill out the PSQI 2 weeks preoperatively and during postoperative visits at the following intervals: 4 weeks, 6 weeks, 3 months, and 6 months. If the patient was not scheduled for follow-up at a specified time, the patient was called and completed the survey over the telephone. Clinical evaluation was not performed if the survey was administered over the telephone. The second assessment of daytime sleepiness was evaluated using the Epworth Sleepiness Scale (ESS) [17], a self-administered and validated questionnaire that quantifies the severity of daytime sleepiness. A score greater than 10 indicates significant sleepiness. This survey was administered preoperatively, at 6 weeks, and at 6 months. Pain was assessed using a visual analog scale (VAS) from 0 to 10. These were assessed at the following intervals: 4 weeks, 6 weeks, 3 months, and 6 months. Demographic data were collected to analyze contributing factors to sleep disturbance, including sex, age, body mass index (BMI), alcohol use, nicotine use, narcotic use, and previous diagnosis of sleep apnea (Table 1). Patients were not sent for sleep apnea screening. Inpatient hospital data were also collected for logistic regression modeling and included factors such as American Society of Anesthesiologists (ASA) classification, tourniquet time, and location of discharge.
331
Statistical Analysis To compare consecutive values, paired t tests were performed on log-transformed data using a Holm-Bonferroni correction. A mixed model linear regression was performed controlling for repeated measures among patients to evaluate potential predictors of PSQI, including sex; age; BMI; sleep apnea; VAS; ESS; ASA; anesthesia; tourniquet time; length of stay (LOS); location of discharge; and nicotine, alcohol and narcotic use. This model was systematically pruned of the least significant factors so that the only factors left were correlated with model predictive performance. R 3.1.1 (R Foundation for Statistical Computing, Vienna, Austria) was used for data analysis. Results Preoperatively, the average PSQI score was 6.3 ± 3.9 (mean ± SD) in patients with knee OA, which increased over the first 6 weeks after surgery (Table 2). Sleep disturbance worsened from baseline during the first 6 weeks postoperatively, as PSQI increased at 4 weeks (P = .01) and 6 weeks (P = .03) compared to baseline. The increase in postoperative PSQI was attributed to shorter duration of sleep and decreased efficiency of sleep. Compared to the 6-week PSQI levels, there was a significant improvement in sleep quality 3 months postoperatively (5.1 ± 3.9; P b .001) and 6 months postoperatively (4.8 ± 4.0; P = .003; Figure), where an average PSQI score less than or equal to 5 is indicative of normal sleep. The 3-month and 6-month PSQI values reduced from baseline, indicating less sleep disturbance, although the difference was not significant (P = .53). These improvements were due to increases in sleep duration, improved efficiency, improved overall sleep quality, and decreased used of medication for sleeping. Simultaneously, the VAS score significantly decreased from baseline (4.8 ± 2.5) over all time points in the postoperative period (6 months, 1.4 ± 2.3; P b .001; Figure; Table 2). Visual analog scale was not associated with PSQI (P = .42); however, there was improved correlation between low VAS and low PSQI at 3 months (ρ = 0.56) and 6 months (ρ = 0.41). Visual analog scale was associated with narcotic use (P = .007; odds ratio, 2.33; 95% confidence interval [14], 1.26-4.29), with an increase in narcotic use over the first 2 weeks, which subsequently decreased during the postoperative period. On the other hand, the ESS did not significantly change over time (P = .60). In addition, sex; age; BMI; ASA; anesthesia type; tourniquet time; LOS; location of discharge; sleep apnea; and nicotine, alcohol, and narcotic use did not affect sleep disturbance after TKA. Discussion
Table 1 Demographics of the Patient Population. Patients (n = 34) a
Age (y) Body mass index (kg/m2)a Sex—female Smoker Alcohol consumption Sleep apnea Diagnosis: osteoarthritis Laterality—right ASA classification Class II Class III Tourniquet timea LOSa Location of discharge Home Rehabilitation facility a
Values are reported in mean ± SD.
65.4 ± 9.2 32.1 ± 4.7 21 (61.8%) 2 (5.6%) 16 (47.1%) 6 (17.6%) 34 (100.0%) 23 (67.6%) 6 (17.6%) 28 (82.4%) 58.8 ± 11.4 2.1 ± 1.3 25 (73.5%) 9 (26.5%)
Multiple studies have been conducted that demonstrate that TKA improves quality of life. Sleep quality is often decreased in patients with knee OA [3-6], but few studies have evaluated the effect of TKA on postoperative sleep disturbance 6 months after surgery. Thus, the purposes of our study were to evaluate the level of sleep disturbance
Table 2 Change in PSQI, VAS Score for Pain, and ESS in Primary, Unilateral TKA Patients. Baseline PSQI Duration of sleep Sleep disturbance Latency Day dysfunction Efficiency Overall sleep quality Medications VAS pain ESS
6.3 0.6 1.6 0.9 0.8 0.4 0.9 1.0 4.8 4.1
± ± ± ± ± ± ± ± ± ±
3.9 0.9 0.8 0.8 0.6 0.8 0.8 1.3 2.5 2.0
4 wk 9.4 1.0 1.8 1.4 1.0 1.2 1.4 1.6 3.1
± ± ± ± ± ± ± ± ±
4.9 1.2 0.6 1.0 0.7 1.3 0.9 1.3 1.9
6 wk 8.8 1.0 1.7 1.3 0.8 1.1 1.5 1.4 1.9 5.0
± ± ± ± ± ± ± ± ± ±
5.0 1.1 0.5 1.2 0.8 1.1 0.8 1.4 1.2 3.0
3 mo 5.1 0.4 1.5 0.8 0.4 0.6 0.8 0.8 1.5
± ± ± ± ± ± ± ± ±
3.9 0.6 0.6 0.8 0.5 0.9 0.9 1.1 2.1
6 mo 4.8 0.7 1.2 0.5 0.5 0.4 0.8 0.9 1.4 4.8
± ± ± ± ± ± ± ± ± ±
4.0 0.9 0.6 0.6 0.7 0.6 0.9 1.3 2.3 3.2
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A.F. Chen et al. / The Journal of Arthroplasty 31 (2016) 330–332
14 12 10 8
PSQI VAS
6
ESS 4 2
to randomize patients to nonoperative treatment after failing conservative therapy and conducted this study as a prospective cohort study. Finally, we did not administer functional scores, such as Knee Society Scores, Western Ontario and McMaster Universities Osteoarthritis Index, or Short Form 36, which may have provided more insight as to why sleep initially worsened after TKA, then improved after 3 months. Despite our limitations, this study demonstrated that sleep quality initially decreases after primary, unilateral TKA but improves after 3 to 6 months after surgery. This can help shape patient expectations after TKA. Future studies are necessary to determine ways to improve sleep quality immediately after TKA, while improving pain and without compromising functional outcomes.
0 Baseline 2 weeks 4 weeks 6 weeks 3 months 6 months Figure. Baseline and postoperative PSQI, VAS score, and ESS after primary, elective TKA.
in the immediate postoperative period after TKA and factors that affect sleep in primary TKA patients. Before undergoing TKA, the patients in our study exhibited poor sleep quality, which is consistent with other studies that have demonstrated increased night pain in knee OA patients [3,4,18,19]. Subsequently, sleep disturbance initially increased from baseline until 6 weeks after surgery. Poor sleep quality after TKA has been established in other studies [14], as well as for up to 1 month after postoperative total hip arthroplasty (THA) [20]. The duration of sleep disturbance was 6 weeks in our patient population, whereas other studies on fasttrack TKA and THA patients have demonstrated normalized sleep levels as early as postoperative days 4 to 9 [13,21]. Worsening sleep patterns after TKA may be attributed to lower function after TKA, as patients may take up to 6 weeks to improve. Although sleep quality initially decreased after surgery, sleep disturbance improved after 3 months, from both baseline levels and sleep levels 6 weeks after surgery. These findings are parallel to findings of improved sleep 3 months after THA [22]. Modalities of sleep disturbance that improved after TKA in our study were similar to improvements of certain PSQI subgroup scores found in another study that only followed patients up to 3 months [15]. The improvement of sleep quality in our study continued until 6 months after surgery. Thus, TKA patients should be counseled that they should expect increased sleep disturbance in the immediate postoperative period, but it should improve by 3 to 6 months. In contrast to PSQI scores, VAS scores after TKA consistently decreased in our study, and VAS scores were never worse than baseline. This is consistent with other studies in literature after elective TKA [12] and even after rotator cuff surgery [23]. However, our VAS levels did not correlate with PSQI scores, unlike other studies in literature [24]. Our findings suggest that sleep disturbances after arthroplasty are not due to pain. Future research is necessary to elucidate whether sleep disturbance after arthroplasty may be due to systemic, neurologic, or circadian rhythm changes. While examining factors that could affect sleep disturbance, none of the parameters that we analyzed were significantly correlated with sleep disturbance after TKA. A study in rotator cuff repair patients found that preoperative narcotic use was associated with postoperative sleep disturbance [23]. Our study found no association with narcotic use, which corroborates with other studies that have demonstrated that opioid use and pain scores have no association with disturbed sleep patterns [13]. There are various limitations to our study. This study was conducted in a small cohort of relatively uniform primary, unilateral TKA patients with ASA II to III, and the findings may not be generalized to sicker patients or patients undergoing revision TKA. This study may have also been strengthened if this was conducted as a prospective, randomized control trial to regularly assess sleep disturbance levels in patients who are candidates for TKA. However, we felt that it would be unreasonable
Acknowledgement We would like to thank Dr Mitchell G. Maltenfort for his invaluable statistical analysis for this project. References 1. Lawrence RC, Felson DT, Helmick CG, et al. National Arthritis Data W. Estimates of the prevalence of arthritis and other rheumatic conditions in the United States. Part II. Arthritis Rheum 2008;58(1):26. 2. Murphy SL, Alexander NB, Levoska M, et al. Relationship between fatigue and subsequent physical activity among older adults with symptomatic osteoarthritis. Arthritis Care Res 2013;65(10):1617. 3. Parmelee PA, Tighe CA, Dautovich ND. Sleep disturbance in osteoarthritis: linkages with pain, disability and depressive symptoms. Arthritis Care Res 2015;67(3):358. 4. Sasaki E, Tsuda E, Yamamoto Y, et al. Nocturnal knee pain increases with the severity of knee osteoarthritis, disturbing patient sleep quality. Arthritis Care Res 2014;66(7):1027. 5. Woolhead G, Gooberman-Hill R, Dieppe P, et al. Night pain in hip and knee osteoarthritis: a focus group study. Arthritis Care Res 2010;62(7):944. 6. Murphy SL, Lyden AK, Phillips K, et al. Association between pain, radiographic severity, and centrally-mediated symptoms in women with knee osteoarthritis. Arthritis Care Res 2011;63(11):1543. 7. Rissanen P, Aro S, Sintonen H, et al. Quality of life and functional ability in hip and knee replacements: a prospective study. Qual Life Res 1996;5(1):56. 8. Rissanen P, Aro S, Slatis P, et al. Health and quality of life before and after hip or knee arthroplasty. J Arthroplast 1995;10(2):169. 9. Escobar A, Quintana JM, Bilbao A, et al. Responsiveness and clinically important differences for the WOMAC and SF-36 after total knee replacement. Osteoarthritis Cartilage 2007;15(3):273. 10. Dowsey MM, Choong PF. The utility of outcome measures in total knee replacement surgery. Int J Rheumatol 2013;2013:506518. 11. March LM, Cross MJ, Lapsley H, et al. Outcomes after hip or knee replacement surgery for osteoarthritis. A prospective cohort study comparing patients' quality of life before and after surgery with age-related population norms. Med J Aust 1999;171(5):235. 12. Cremeans-Smith JK, Millington K, Sledjeski E, et al. Sleep disruptions mediate the relationship between early postoperative pain and later functioning following total knee replacement surgery. J Behav Med 2006;29(2):215. 13. Krenk L, Jennum P, Kehlet H. Sleep disturbances after fast-track hip and knee arthroplasty. Br J Anaesth 2012;109(5):769. 14. Herrero-Sanchez MD, Garcia-Inigo Mdel C, Nuno-Beato-Redondo BS, et al. Association between ongoing pain intensity, health-related quality of life, disability and quality of sleep in elderly people with total knee arthroplasty. Cien Saude Colet 1881;19(6):2014. 15. Er MS, Altinel EC, Altinel L, et al. An assessment of sleep quality in patients undergoing total knee arthroplasty before and after surgery. Acta Orthop Traumatol Turc 2014; 48(1):50. 16. Buysse DJ, Reynolds III CF, Monk TH, et al. The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Res 1989;28(2):193. 17. Johns MW. A new method for measuring daytime sleepiness: the Epworth sleepiness scale. Sleep 1991;14(6):540. 18. Foley D, Ancoli-Israel S, Britz P, et al. Sleep disturbances and chronic disease in older adults: results of the 2003 National Sleep Foundation Sleep in America Survey. J Psychosom Res 2004;56(5):497. 19. McCurry SM, Von Korff M, Vitiello MV, et al. Frequency of comorbid insomnia, pain, and depression in older adults with osteoarthritis: predictors of enrollment in a randomized treatment trial. J Psychosom Res 2011;71(5):296. 20. Myoji Y, Fujita K, Mawatari M, et al. Changes in sleep-wake rhythms, subjective sleep quality and pain among patients undergoing total hip arthroplasty. Int J Nurs Pract 2014 Apr 30 [Epub ahead of print]. 21. Krenk L, Jennum P, Kehlet H. Activity, sleep and cognition after fast-track hip or knee arthroplasty. J Arthroplast 2013;28(8):1265. 22. Fielden JM, Gander PH, Horne JG, et al. An assessment of sleep disturbance in patients before and after total hip arthroplasty. J Arthroplast 2003;18(3):371. 23. Austin L, Pepe M, Tucker B, et al. Arthroscopic rotator cuff repair: the characterization of preoperative and postoperative sleep disturbance. Am J Sports Med 2015 [in press]. 24. Wylde V, Rooker J, Halliday L, et al. Acute postoperative pain at rest after hip and knee arthroplasty: severity, sensory qualities and impact on sleep. Orthop Traumatol Surg Res 2011;97(2):139.
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Prospective Evaluation of Sleep Disturbances After Total Knee Arthroplasty Antonia F. Chen, MD/MBA, Fabio R. Orozco, MD, Luke S. Austin, MD, Zachary D. Post, MD, Carl A. Deirmengian, MD, Alvin C. Ong, MD The Rothman Institute, Philadelphia, Pennsylvania
a r t i c l e
i n f o
Article history: Received 18 February 2015 Accepted 31 July 2015 Keywords: total knee arthroplasty sleep pain narcotics knee osteoarthritis
a b s t r a c t Sleep disturbance after total knee arthroplasty (TKA) has not been studied 6 months after surgery. A prospective study was conducted on 34 primary, unilateral TKA patients preoperatively until 6 months postoperatively. Sleep quality was measured using the Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale. Pain was measured on a visual analog scale. Sleep quality worsened from baseline during the first 6 weeks postoperatively (P = .03), but improved at 3 and 6 months (P = .003). Pain scores decreased from baseline over all time points, and there was no correlation between sleep quality and pain. The Epworth Sleepiness Scale did not change over time. This study can be used to counsel TKA patients to expect initial sleep disturbances that improve by 3 months. © 2016 Elsevier Inc. All rights reserved.
Symptomatic knee osteoarthritis (OA) is a condition that affects more than 37.5% of the adults in the United States [1]. These patients experience a worsening in their quality of life and a decreased ability to perform activities of daily living [2]. Studies have also reported that patients with OA have decreased sleep quality, in association with increased night pain, which correlates with radiographic severity of disease [3-6]. To improve patients' lives, the most common surgical treatment for knee OA is total knee arthroplasty (TKA). Studies have demonstrated that performing TKA can improve patients' health-related quality of life and that these levels mostly return to those of the general population [7,8]. Other clinical outcomes, such as Short Form 36, Knee Society Score, and Western Ontario and McMaster Osteoarthritis Index, also improve after TKA [9-11]. However, studies reporting on the changes of sleep quality after TKA have had variable results. A previous study conducted on 110 TKAs found that sleep disruptions 1 month after surgery were associated with increased pain during the same period and limited function 3 months postoperatively [12]. A study involving 10 subjects undergoing fast-track hip and knee arthroplasty demonstrated that rapid eye movement sleep was significantly decreased on the night after surgery but returned to preadmission levels on the fourth postoperative night [13]. One study demonstrated that within 1 month after surgery, patients who undergo
One or more of the authors of this paper have disclosed potential or pertinent conflicts of interest, which may include receipt of payment, either direct or indirect, institutional support, or association with an entity in the biomedical field which may be perceived to have potential conflict of interest with this work. For full disclosure statements refer to http://dx.doi.org/10.1016/j.arth.2015.07.044. Reprint requests: Alvin Ong, MD, 2500 English Creek Ave, Building 1300, Egg Harbor Township, NJ 08234. http://dx.doi.org/10.1016/j.arth.2015.07.044 0883-5403/© 2016 Elsevier Inc. All rights reserved.
TKA have worse sleep quality compared to controls [14]. However, another study demonstrated that there were less sleep disturbances 3 months after TKA and that sleep quality improved by that time [15]. Despite these observations, factors associated with sleep disturbances among patients undergoing elective TKA 6 months after surgery remain unknown. The purposes of this study are to prospectively evaluate preoperative and postoperative sleep disturbance in patients undergoing TKA and to identify risk factors associated with sleep disturbance in TKA patients.
Methods and Materials A prospective cohort study on primary TKA patients was conducted from June 2012 to January 2013. Patients were included if they were undergoing elective primary TKA, were older than 18 years, and were willing and able to complete pre and postoperative surveys. Exclusion criteria included a history of substance abuse, workman's compensation patients, revision TKA patients, patients pending current litigation, history of prescription or supplemental sleeping aids, or patients who did not consent to fill out questionnaires. Only 34 patients were included in the study, as they agreed to fill out the questionnaires associated with this study on a regular basis (baseline, 4 weeks, 6 weeks, 3 months, and 6 months). There were 510 patients who declined to participate in the study during the study period because they did not want to fill out the assessments; however, their demographics were similar to the study population. Institutional review board approval was obtained, and all patients signed a written consent before participating in our study. All patients underwent primary TKA using the midvastus approach under spinal anesthesia, and intraoperatively, all patients received
A.F. Chen et al. / The Journal of Arthroplasty 31 (2016) 330–332
10 mg/kg of intravenous tranexamic acid, intravenous decadron, intravenous ondansteron, and a pericapsular injection consisting of 266 mg bupivacaine liposome injectable suspension (Exparel), 30 mg ketorolac, 150 mg bupivacaine with epinephrine, and 20 mL and saline. Primary TKA was performed by 2 arthroplasty surgeons using the same implants and same postoperative rehabilitation protocols. All patients ambulated on the day of surgery with supervised physical therapy. Patients received the following pain medications during the postoperative hospital period including oxycodone extended release 10 mg by mouth once in postoperative anesthesia care unit, intravenous ketorolac, and oral acetaminophen. No patients were given prescription or supplemental sleeping aids in the postoperative period. Patients were discharged an average of 2.1 days after surgery (range, 1.0-7.0) and were discharged with oxycodone or hydrocodone-acetaminophen. The presence of sleep disturbances was evaluated by 2 separate assessments. First, sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) [16], a self-rated questionnaire that assesses sleep quality and disturbances over a 1-month time interval. Nineteen individual items generate 7 “component” scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. The sum of scores for these 7 components yields 1 global score, with a maximum score of 21. A higher score indicates worse sleep dysfunction, and a score greater than 5 indicates poor sleep quality. All patients were asked to fill out the PSQI 2 weeks preoperatively and during postoperative visits at the following intervals: 4 weeks, 6 weeks, 3 months, and 6 months. If the patient was not scheduled for follow-up at a specified time, the patient was called and completed the survey over the telephone. Clinical evaluation was not performed if the survey was administered over the telephone. The second assessment of daytime sleepiness was evaluated using the Epworth Sleepiness Scale (ESS) [17], a self-administered and validated questionnaire that quantifies the severity of daytime sleepiness. A score greater than 10 indicates significant sleepiness. This survey was administered preoperatively, at 6 weeks, and at 6 months. Pain was assessed using a visual analog scale (VAS) from 0 to 10. These were assessed at the following intervals: 4 weeks, 6 weeks, 3 months, and 6 months. Demographic data were collected to analyze contributing factors to sleep disturbance, including sex, age, body mass index (BMI), alcohol use, nicotine use, narcotic use, and previous diagnosis of sleep apnea (Table 1). Patients were not sent for sleep apnea screening. Inpatient hospital data were also collected for logistic regression modeling and included factors such as American Society of Anesthesiologists (ASA) classification, tourniquet time, and location of discharge.
331
Statistical Analysis To compare consecutive values, paired t tests were performed on log-transformed data using a Holm-Bonferroni correction. A mixed model linear regression was performed controlling for repeated measures among patients to evaluate potential predictors of PSQI, including sex; age; BMI; sleep apnea; VAS; ESS; ASA; anesthesia; tourniquet time; length of stay (LOS); location of discharge; and nicotine, alcohol and narcotic use. This model was systematically pruned of the least significant factors so that the only factors left were correlated with model predictive performance. R 3.1.1 (R Foundation for Statistical Computing, Vienna, Austria) was used for data analysis. Results Preoperatively, the average PSQI score was 6.3 ± 3.9 (mean ± SD) in patients with knee OA, which increased over the first 6 weeks after surgery (Table 2). Sleep disturbance worsened from baseline during the first 6 weeks postoperatively, as PSQI increased at 4 weeks (P = .01) and 6 weeks (P = .03) compared to baseline. The increase in postoperative PSQI was attributed to shorter duration of sleep and decreased efficiency of sleep. Compared to the 6-week PSQI levels, there was a significant improvement in sleep quality 3 months postoperatively (5.1 ± 3.9; P b .001) and 6 months postoperatively (4.8 ± 4.0; P = .003; Figure), where an average PSQI score less than or equal to 5 is indicative of normal sleep. The 3-month and 6-month PSQI values reduced from baseline, indicating less sleep disturbance, although the difference was not significant (P = .53). These improvements were due to increases in sleep duration, improved efficiency, improved overall sleep quality, and decreased used of medication for sleeping. Simultaneously, the VAS score significantly decreased from baseline (4.8 ± 2.5) over all time points in the postoperative period (6 months, 1.4 ± 2.3; P b .001; Figure; Table 2). Visual analog scale was not associated with PSQI (P = .42); however, there was improved correlation between low VAS and low PSQI at 3 months (ρ = 0.56) and 6 months (ρ = 0.41). Visual analog scale was associated with narcotic use (P = .007; odds ratio, 2.33; 95% confidence interval [14], 1.26-4.29), with an increase in narcotic use over the first 2 weeks, which subsequently decreased during the postoperative period. On the other hand, the ESS did not significantly change over time (P = .60). In addition, sex; age; BMI; ASA; anesthesia type; tourniquet time; LOS; location of discharge; sleep apnea; and nicotine, alcohol, and narcotic use did not affect sleep disturbance after TKA. Discussion
Table 1 Demographics of the Patient Population. Patients (n = 34) a
Age (y) Body mass index (kg/m2)a Sex—female Smoker Alcohol consumption Sleep apnea Diagnosis: osteoarthritis Laterality—right ASA classification Class II Class III Tourniquet timea LOSa Location of discharge Home Rehabilitation facility a
Values are reported in mean ± SD.
65.4 ± 9.2 32.1 ± 4.7 21 (61.8%) 2 (5.6%) 16 (47.1%) 6 (17.6%) 34 (100.0%) 23 (67.6%) 6 (17.6%) 28 (82.4%) 58.8 ± 11.4 2.1 ± 1.3 25 (73.5%) 9 (26.5%)
Multiple studies have been conducted that demonstrate that TKA improves quality of life. Sleep quality is often decreased in patients with knee OA [3-6], but few studies have evaluated the effect of TKA on postoperative sleep disturbance 6 months after surgery. Thus, the purposes of our study were to evaluate the level of sleep disturbance
Table 2 Change in PSQI, VAS Score for Pain, and ESS in Primary, Unilateral TKA Patients. Baseline PSQI Duration of sleep Sleep disturbance Latency Day dysfunction Efficiency Overall sleep quality Medications VAS pain ESS
6.3 0.6 1.6 0.9 0.8 0.4 0.9 1.0 4.8 4.1
± ± ± ± ± ± ± ± ± ±
3.9 0.9 0.8 0.8 0.6 0.8 0.8 1.3 2.5 2.0
4 wk 9.4 1.0 1.8 1.4 1.0 1.2 1.4 1.6 3.1
± ± ± ± ± ± ± ± ±
4.9 1.2 0.6 1.0 0.7 1.3 0.9 1.3 1.9
6 wk 8.8 1.0 1.7 1.3 0.8 1.1 1.5 1.4 1.9 5.0
± ± ± ± ± ± ± ± ± ±
5.0 1.1 0.5 1.2 0.8 1.1 0.8 1.4 1.2 3.0
3 mo 5.1 0.4 1.5 0.8 0.4 0.6 0.8 0.8 1.5
± ± ± ± ± ± ± ± ±
3.9 0.6 0.6 0.8 0.5 0.9 0.9 1.1 2.1
6 mo 4.8 0.7 1.2 0.5 0.5 0.4 0.8 0.9 1.4 4.8
± ± ± ± ± ± ± ± ± ±
4.0 0.9 0.6 0.6 0.7 0.6 0.9 1.3 2.3 3.2
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14 12 10 8
PSQI VAS
6
ESS 4 2
to randomize patients to nonoperative treatment after failing conservative therapy and conducted this study as a prospective cohort study. Finally, we did not administer functional scores, such as Knee Society Scores, Western Ontario and McMaster Universities Osteoarthritis Index, or Short Form 36, which may have provided more insight as to why sleep initially worsened after TKA, then improved after 3 months. Despite our limitations, this study demonstrated that sleep quality initially decreases after primary, unilateral TKA but improves after 3 to 6 months after surgery. This can help shape patient expectations after TKA. Future studies are necessary to determine ways to improve sleep quality immediately after TKA, while improving pain and without compromising functional outcomes.
0 Baseline 2 weeks 4 weeks 6 weeks 3 months 6 months Figure. Baseline and postoperative PSQI, VAS score, and ESS after primary, elective TKA.
in the immediate postoperative period after TKA and factors that affect sleep in primary TKA patients. Before undergoing TKA, the patients in our study exhibited poor sleep quality, which is consistent with other studies that have demonstrated increased night pain in knee OA patients [3,4,18,19]. Subsequently, sleep disturbance initially increased from baseline until 6 weeks after surgery. Poor sleep quality after TKA has been established in other studies [14], as well as for up to 1 month after postoperative total hip arthroplasty (THA) [20]. The duration of sleep disturbance was 6 weeks in our patient population, whereas other studies on fasttrack TKA and THA patients have demonstrated normalized sleep levels as early as postoperative days 4 to 9 [13,21]. Worsening sleep patterns after TKA may be attributed to lower function after TKA, as patients may take up to 6 weeks to improve. Although sleep quality initially decreased after surgery, sleep disturbance improved after 3 months, from both baseline levels and sleep levels 6 weeks after surgery. These findings are parallel to findings of improved sleep 3 months after THA [22]. Modalities of sleep disturbance that improved after TKA in our study were similar to improvements of certain PSQI subgroup scores found in another study that only followed patients up to 3 months [15]. The improvement of sleep quality in our study continued until 6 months after surgery. Thus, TKA patients should be counseled that they should expect increased sleep disturbance in the immediate postoperative period, but it should improve by 3 to 6 months. In contrast to PSQI scores, VAS scores after TKA consistently decreased in our study, and VAS scores were never worse than baseline. This is consistent with other studies in literature after elective TKA [12] and even after rotator cuff surgery [23]. However, our VAS levels did not correlate with PSQI scores, unlike other studies in literature [24]. Our findings suggest that sleep disturbances after arthroplasty are not due to pain. Future research is necessary to elucidate whether sleep disturbance after arthroplasty may be due to systemic, neurologic, or circadian rhythm changes. While examining factors that could affect sleep disturbance, none of the parameters that we analyzed were significantly correlated with sleep disturbance after TKA. A study in rotator cuff repair patients found that preoperative narcotic use was associated with postoperative sleep disturbance [23]. Our study found no association with narcotic use, which corroborates with other studies that have demonstrated that opioid use and pain scores have no association with disturbed sleep patterns [13]. There are various limitations to our study. This study was conducted in a small cohort of relatively uniform primary, unilateral TKA patients with ASA II to III, and the findings may not be generalized to sicker patients or patients undergoing revision TKA. This study may have also been strengthened if this was conducted as a prospective, randomized control trial to regularly assess sleep disturbance levels in patients who are candidates for TKA. However, we felt that it would be unreasonable
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