Abstracts

Introduction

Osteoarthritis (OA) is the most prevalent medical arthritic condition worldwide. For instance, it affects 3532 per 100.000 people in the United States of America¹1. Bedson J, Jordan K, Croft P. The prevalence and history of knee osteoarthritis in general practice: a case-control study. Fam Pract 2005; 22(1):103-108.^,22. Sacks JJ, Luo YH, Helmick CG. Prevalence of specific types of arthritis and other rheumatic conditions in the ambulatory health care system in the United States, 2001-2005. Arthritis Care Res (Hoboken) 2010; 62(4):460-464.. Population based longitudinal studies in the USA have shown that the lifetime risk of knee OA increases with age³3. Murphy L, Schwartz TA, Helmick CG, Renner JB, Tudor G, Koch G, Dragomir A, Kalsbeek WD, Luta G, Jordan JM. Lifetime risk of symptomatic knee osteoarthritis. Arthritis Rheum 2008; 59(9):1207-1213.. In fact, more than 10% of elder people in the USA will suffer knee OA⁴4. Dillon CF, Rasch EK, Gu Q, Hirsch R. Prevalence of knee osteoarthritis in the United States: arthritis data from the Third National Health and Nutrition Examination Survey 1991-94. J Rheumatol 2006; 33(11):2271-2279.. Total knee arthroplasty (TKA) is one of the main therapeutic options for subjects with chronic knee OA. Therefore, the number of TKA will further increase in the next decades because of the aging population and an associated increasing in prevalence of arthritic diseases and joint degeneration⁵5. Birrell F, Johnell O, Silman A. Projecting the need for hip replacement over the next three decades: influence of changing demography and threshold for surgery. Ann Rheum Dis 1999; 58(9):569-572.^,66. Badley EM, Crotty M. An international comparison of the estimated effect of the aging of the population on the major cause of disablement, musculoskeletal disorders. J Rheumatol 1995; 22(10):1934-1940..

Patients who had received TKA differ greatly in length and quality of their recovery, as indicated by their reports of pain and the speed with which they are able to recover independency⁷7. Lingard EA, Katz JN, Wright EA, Sledge CB, Group KO. Predicting the outcome of total knee arthroplasty. J Bone Joint Surg Am 2004; 86-A(10):2179-2186.. Although primary TKA has revolutionized the management of patients with end-stage OA, 11%-19% of patients with TKA are not satisfied with their recovery⁸8. Bourne RB, Chesworth BM, Davis AM, Mahomed NN, Charron KD. Patient satisfaction after total knee arthroplasty: who is satisfied and who is not? Clin Orthop Relat Res 2010; 468(1):57-63.. Subjects undergoing TKA are less active according to recommendations for achieving health-enhancing activity levels, more than 10,000 steps per day⁹9. Naal FD, Impellizzeri FM. How active are patients undergoing total joint arthroplasty?: A systematic review. Clin Orthop Relat Res 2010; 468(7):1891-1904..

Patients who undergo TKA sometimes report high levels of pain and disability. In fact, despite the enormous success of this procedure, chronic neuropathic pain can be developed postoperatively being distressing and difficult to treat once it is established¹⁰10. Buvanendran A, Kroin JS, Della Valle CJ, Kari M, Moric M, Tuman KJ. Perioperative oral pregabalin reduces chronic pain after total knee arthroplasty: a prospective, randomized, controlled trial. Anesth Analg 2010; 110(1):199-207.. The incidence of chronic neuropathic pain after TKA surgery has not decreased, in spite of advances in surgical procedures and anesthetic management. Pain that persists after the surgery is a major, if largely unrecognized, clinical problem for these patients¹¹11. Kehlet H, Jensen TS, Woolf CJ. Persistent postsurgical pain: risk factors and prevention. Lancet 2006; 367(9522):1618-1625.. In fact, neuropathic pain is as high as 12.7% at 6 month after the surgery¹²12. Harden RN, Bruehl S, Stanos S, Brander V, Chung OY, Saltz S, Adams A, Stulberg SD. Prospective examination of pain-related and psychological predictors of CRPS-like phenomena following total knee arthroplasty: a preliminary study. Pain 2003; 106(3): 393-400.. Puolakka et al.¹³13. Puolakka PA, Rorarius MG, Roviola M, Puolakka TJ, Nordhausen K, Lindgren L. Persistent pain following knee arthroplasty. Eur J Anaesthesiol 2010; 27(5):455-460. reported that the intensity of early postoperative pain and delayed surgery increase the risk of persistent pain after TKA. Nevertheless, the severity of pain and disability may depend of several factors including age, gender, body mass index, and sport activities¹⁴14. Merle-Vincent F, Couris CM, Schott AM, Perier M, Conrozier S, Conrozier T, Piperno M, Mathieu P, Vignon E. Cross-sectional study of pain and disability at knee replacement surgery for osteoarthritis in 299 patients. Joint Bone Spine 2007; 74(6):612-616.. However, with increasing life expectancy and elective surgery improving quality of life, age alone is not a factor that affects the outcome of TKA and should not be a limiting factor when considering who should receive the procedure¹⁵15. Jones CA, Voaklander DC, Johnston DW, Suarez-Almazor ME. The effect of age on pain, function, and quality of life after total hip and knee arthroplasty. Arch Intern Med 2001; 161(3):454-460..

One of the objectives of TKA is to improve the quality of life and function of patients with long-lasting and severe knee OA. Large improvements have been reported for pain and function after TKA, while small to moderate changes are also seen in other areas related to health-related quality of life¹⁶16. Jones CA, Voaklander DC, Johnston DW, Suarez-Almazor ME. Health related quality of life outcomes after total hip and knee arthroplasties in a community based population. J Rheumatol 2000; 27(7):1745-1752.. An important point is that the intensity of pain is correlated with the decrease in both physical and mental component of the SF-12 quality of life questionnaire¹⁷17. Wu CL, Naqibuddin M, Rowlingson AJ, Lietman SA, Jermyn RM, Fleisher LA. The effect of pain on health-related quality of life in the immediate postoperative period. Anesth Analg 2003; 97(4):1078-1085.. Further, an increase in postoperative pain could be able to decrease the quality of life of the patient in the immediate postoperative period¹⁷17. Wu CL, Naqibuddin M, Rowlingson AJ, Lietman SA, Jermyn RM, Fleisher LA. The effect of pain on health-related quality of life in the immediate postoperative period. Anesth Analg 2003; 97(4):1078-1085.. It seems that physical function is substantially influenced by the pain experienced by the patients. Stratford et al.¹⁸18. Stratford PW, Kennedy DM, Woodhouse LJ. Performance measures provide assessments of pain and function in people with advanced osteoarthritis of the hip or knee. Phys Ther 2006; 86(11):1489-1496. found that improvements in self-rated recovery corresponded strongly with improvements in patient perceived pain. Patients who have advanced knee OA and subsequent TKA are not able of discriminating the experienced pain from their ability to perform functional tasks¹⁹19. Mizner RL, Petterson SC, Clements KE, Zeni JAJ, Irrgang JJ, Snyder-Mackler L. Measuring functional improvement after total knee arthroplasty requires both performance-based and patient-report assessments: a longitudinal analysis of outcomes. J Arthroplasty 2011; 26(5):728-737..

Finally, one important topic in chronic pain is the quality of sleep. Individuals with non-surgical chronic pain syndromes reporting more severe pain experience poorer sleep quality, delayed sleep onset, increased number of awakenings and fewer hours of sleep per night²⁰20. Martín-Herrero C, Rodrigues de Souza DP, Alburquerque-Sendín F, Ortega-Santiago R, Fernández-de-Las-Peñas C. Myofascial trigger points, pain, disability and quality of sleep in patients with chronic tension-type headache: a pilot study. Rev Neurol 2012; 55(4):193-199.

21. Muñoz-Muñoz S, Muñoz-García MT, Alburquerque-Sendín F, Arroyo-Morales M, Fernández-de-las-Peñas C. Myofascial trigger points, pain, disability, and sleep quality in individuals with mechanical neck pain. J Manipulative Physiol Ther 2012; 35(8):608-613.^-2222. Valenza MC, Valenza G, González-Jiménez E, De-la-Llave-Rincón AI, Arroyo-Morales M, Fernández-de-Las-Peñas C. Alteration in sleep quality in patients with mechanical insidious neck pain and whiplash-associated neck pain. Am J Phys Med Rehabil 2012; 91(7):584-591.. In fact, one of the most common complaints of the individuals following surgery is increase difficulty for sleeping. In such scenario, sleep difficulties have been related to higher intensity of pain²³23. Naughton F, Ashworth P, Skevington SM. Does sleep quality predict pain-related disability in chronic pain patients? The mediating roles of depression and pain severity. Pain 2007; 127(3):243-252. and lower functioning in patients with chronic pain, although this relation depends on the patient characteristics²⁴24. Baldwin CM, Ervin AM, Mays MZ, Robbins J, Shafazand S, Walsleben J, Weaver T. Sleep disturbances, quality of life, and ethnicity: the Sleep Heart Health Study. J Clin Sleep Med 2010; 6(2):176-183.. Therefore, interventions targeting sleep disruptions may improve the speed and quality of patient recovery after TKA and other possible surgical procedures, underscoring the importance of adequate sleep during the postsurgical recovery period²⁵25. Cremeans-Smith JK, Mllington K, Sledjeski E, Greene K, Delahanty DL. Sleep disruptions mediate the relationship between early postoperative pain and later functioning following total knee replacement surgery. J Behav Med 2006; 29(2):215-222.. For a better understanding of the complex clinical presentation of individuals after receiving TKA, the current study aims to identify the potential relationships between pain intensity, health related quality of life, disability and sleep quality in a sample of elderly people who had received TKA and to identify the behavioral differences of these variables in relation to age and body mass index.

Methods

Individuals with end-stage knee OA who had received total knee arthroplasty (TKA) from an Orthopedic Service of a Public Hospital were recruited. All participants underwent a TKA with a tri-compartmental, cemented endoprosthesis with a medial parapatellar surgical approach. In addition, sex- and age-comparable subjects who had no knee pain or other long lasting pain problems in the past year were also included as controls. Participants were excluded if presented any of the following: 1, previous TKA; 2, previous lower extremity surgery; 3, cervical surgery; 4, diagnosis of radiculopathy or myelopathy; 5, diagnosis of fibromyalgia; 6, if they were cognitive impaired; or, 7, if they had received rehabilitation in the past 6 months before the study. The protocol was approved by the local human research committee and it was conducted according to the declaration of Helsinki. All subjects signed an informed consent prior to their inclusion in the study.

Demographic data including age, gender, weight, height, BMI, past medical history and location and nature of the symptoms were collected. An 11-point numerical pain rate scale (NPRS, 0: no pain; 10: maximum pain) was used to determine the mean current intensity of pain, worst and lowest intensity of pain experienced in the preceding week²⁶26. Jensen MP, Turner JA, Romano JM, Fisher LD. Comparative reliability and validity of chronic pain intensity measures. Pain 1999; 83(2):157-162..

The functional status of the patients was evaluated using the Western Ontario and McMaster Universities (WOMAC) index. The WOMAC consists of a self-administered questionnaire reflecting 3 dimensions: pain (5 items), stiffness (5 items), and physical function (17 items) in individuals with OA in the lower limb²⁷27. McConnell S, Kolopack P, Davis AM. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC): a review of its utility and measurement properties. Arthritis Rheum 2001; 45(5): 453-461.. The total score of the questionnaire has shown to have high reliability (ICC: 0.92-0.97) and a standard error of measurement (SEM) ranging between 5.1 and 7.2 points²⁸28. Williams VJ, Piva SR, Irrgang JJ, Crossley C, Fitzgerald GK. Comparison of reliability and responsiveness of patient-reported clinical outcome measures in knee osteoarthritis rehabilitation. J Orthop Sports Phys Ther 2012; 42(8):716-723.. In the current study, we used the validated Spanish version of the WOMAC questionnaire which is a valid and reliable instrument in patients with knee OA²⁹29. Escobar A, Quintana JM, Bilbao A, Azkárate J, Güenaga JI. Validation of the Spanish version of the WOMAC questionnaire for patients with hip or knee osteoarthritis. Western Ontario and McMaster Universities Osteoarthritis Index. Clin Rheumatol 2002; 21(6):466-471..

The health-related quality of life was assessed with the Medical Outcomes Study Short Form 36 (SF-36) questionnaire which assessed 8 domains: physical function, physical role, bodily pain, general health, vitality, social function, emotional role, and mental health³⁰30. Ware JE, Sherbourne CD. The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection. Med Care 1992; 30(6):473-483.. After summing the Likert-scaled items, each scale is categorized from 0 (lowest level of functioning) to 100 (highest level)³¹31. Cruz LN, Fleck MP, Oliveira MR, Camey SA, Hoffmann JF, Bagattini AM, Polanczyk CA. Health-related quality of life in Brazil: normative data for the SF-36 in a general population sample in the south of the country. Cien Saude Colet 2013; 18(7):1911-1921.. The SF-36 questionnaire has demonstrated the best ability to discriminate between individuals with health problems and healthy people³²32. Campolina AG, Dini PS, Ciconelli RM. The impact of chronic disease on the quality of life of the elderly in São Paulo (SP, Brazil). Cien Saude Colet 2011; 16(6):2919-2925.. We used the validated Spanish version of the SF-36 which is a valid, reliable, and responsive instrument³³33. Alonso J, Regidor E, Barrio G, Pietro L, Rodrigues C, Fuente L. Valoración poblacionales de referencia de la versión española del Cuestionario de Salud SF-36. Med Clin (Barc) 1998; 111(11):401-416..

Sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI)³⁴34. Cole JC, Dubois D, Kosinski M. Use of patient-reported sleep measures in clinical trials of pain treatment: a literature review and synthesis of current sleep measures and a conceptual model of sleep disturbance in pain. Clin Ther 2007; 29(Supl.): 2580-2588.. This questionnaire appraises sleep quality over a 1-month period through a standardized questionnaire differentiating between good and poor sleepers. It consists of 19 self-rated questions and 5 questions answered by bedmates/roommates. PSQI items use varying response categories recording the usual bed time, usual wake time, number of actual hours slept, and number of minutes to fall asleep, as well as forced-choice Likert-type responses (0-3). The sum of the scores for the components yields one global score (0-21) where higher score indicates worse sleep quality³⁵35. Buysse DJ, Reynolds CF, Monk TH, Berman SR, Kupfer DJ. The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Res 1989; 28(2):193-213.. Buysse et al.³⁵35. Buysse DJ, Reynolds CF, Monk TH, Berman SR, Kupfer DJ. The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Res 1989; 28(2):193-213. reported that the PSQI has good internal consistency (α : 0.83) and test-retest reliability (r: 0.85). A total score > 8.0 has been found to be indicative of poor sleep quality³⁶36. Carpenter JS, Andrykowski MA. Psychometric evaluation of the Pittsburgh Sleep Quality Index. J Psychosom Res 1998; 45(1):5-13..

Data were analyzed with the SPSS statistical package (18.0 Version). Descriptive data was collected on all patients. The Kolmogorov-Smirnov test showed that all data showed a normal distribution (P > 0.05); therefore, parametric tests were used in the analysis. The chi square (χ²2. Sacks JJ, Luo YH, Helmick CG. Prevalence of specific types of arthritis and other rheumatic conditions in the ambulatory health care system in the United States, 2001-2005. Arthritis Care Res (Hoboken) 2010; 62(4):460-464. test was used to analyze the differences in the distribution of sex between groups. The unpaired Student t-test was used for assessing differences in pain intensity (NPRS), disability (WOMAC), quality of life (SF-36) and sleep quality (PSQI) between groups. The Pearson correlation test (r) was used to determine the association between pain, function, health-related quality of life and sleep quality within the group of individuals who had received TKA. The statistical analysis was conducted at 95% confidence level, and a P value < 0.05 was considered statistically significant.

Results

Twenty-four (n = 24) subjects who had received TKA the previous month (mean: 28 days), 4 male-20 female, mean age: 66 ± 9 years, and 21 comparable controls, 8 male-13 females, mean age: 70 ± 9 years old, were included. No significant differences between groups were detected for age, weight, height and BMI (Table 1).

The analysis revealed significant differences between groups for physical function, social role, physical role, and bodily pain (P < 0.05): individuals who had received TKA exhibited lower quality of life than those in the control group. No significant differences for mental health, emotional role, vitality, and general health were observed ( Table 1 ). Similarly, individuals who had received TKA exhibited lower function (WOMAC) and worse sleep quality (PSQI) than those within the control group (P < 0.05, Table 1 ).

The association between clinical and demographic data with health-related quality of life, disability, and sleep quality showed a complex pattern. Older age was associated with higher vitality and function (WOMAC). BMI was negatively positively associated with the worst pain (r = 0.409; P = 0.047) and the least pain (r = 0.513; P = 0.01) experienced the previous week: the higher the BMI, the higher the intensity of pain. No significant associations between time from surgery, weight or height with any other variable were found (Table 2).

The mean intensity of ongoing pain showed moderate-high negative associations with physical function, social role, mental health, vitality and general health domains of the SF-36 questionnaire ( Table 2 ): the higher the intensity of ongoing pain, the lower the quality of life in these domains. Additionally, positive significant associations between the intensity of ongoing pain with disability (WOMAC, r = 0.669; P < 0.01) and sleep quality (PSQI, r = 0.450; P = 0.027) were also observed ( Table 2 ): the higher the intensity of the pain, the lower the function or the worse the sleep quality.

Further, several associations between the different domains of the SF-36 quality of life questionnaire with disability and sleep quality were found ( Table 2 ). Disability was negatively associated with physical function, mental health, vitality, bodily pain, or general health (all, p < 0.05): the higher the disability, the lower the quality of life in these domains. Finally, sleep quality was also negatively associated with social role, mental health, vitality, and general health (all, P < 0.05): the worse the sleep quality, the lower the quality of life in these quality of life domains ( Table 2 ).

Discussion

The current study found that elder people who had received TKA exhibited lower physical function and worse sleep quality than comparable elder people without long lasting pain. Several associations between the intensity of ongoing pain, disability, quality of life, and sleep quality were observed within the TKA group demonstrating the multidimensional aspect of the TKA experience.

We found that higher intensity of ongoing pain after TKA was associated with worse quality of life, lower function, and worse quality of sleep; suggesting that pain after TKA plays an important role in the recovery of these patients. In fact, mechanisms regarding OA-related pain are not completely understood. There is increasing evidence suggesting that central sensitivity plays an important role in pain processes in patients with OA pain suggesting complex mechanisms³⁷37. Allen K. Central pain contributions in osteoarthritis: next steps for improving recognition and treatment?. Arthritis Res Ther 2011; 13(6):133.. It has been found that the intensity of early postoperative pain and delayed surgery increase the risk of the persistent pain 3 months after surgery¹³13. Puolakka PA, Rorarius MG, Roviola M, Puolakka TJ, Nordhausen K, Lindgren L. Persistent pain following knee arthroplasty. Eur J Anaesthesiol 2010; 27(5):455-460.. In this study, if the pain intensity during the first postoperative week was moderate or higher, the risk for the development of persistent pain was higher than in individuals with mild pain¹³13. Puolakka PA, Rorarius MG, Roviola M, Puolakka TJ, Nordhausen K, Lindgren L. Persistent pain following knee arthroplasty. Eur J Anaesthesiol 2010; 27(5):455-460.. Similarly, the presence of acute postoperative pain was a risk factor for the development of chronic post-surgical pain¹¹11. Kehlet H, Jensen TS, Woolf CJ. Persistent postsurgical pain: risk factors and prevention. Lancet 2006; 367(9522):1618-1625.. It is important to note that acute postoperative pain after TKA is poorly managed³⁸38. Wylde V, Rooker J, Halliday L, Blom A. Acute postoperative pain at rest after hip and knee arthroplasty: severity, sensory qualities and impact on sleep. Orthop Traumatol Surg Res 2011; 97(2):139-144. and interferes with walking, an action critical for postoperative recovery and achievement of rehabilitation goals³⁹39. Dihle A, Helseth S, Kongsgaard UE, Paul SM, Miaskowski C. Using the American Pain Society's patient outcome questionnaire to evaluate the quality of postoperative pain management in a sample of Norwegian patients. J Pain 2006; 7(4):272-280.. Therefore, our study supports the relevance of the intensity of ongoing pain after TKA by influencing different aspects of the patients. Further, it is well known that pain negatively influences various domains of health suggesting a critical need for the dissemination of proper interventions to enhance the recognition and treatment of pain among adult community-dwellers⁴⁰40. Strine TW, Hootman JM, Chapman DP, Okoro CA, Balluz L. Health-related quality of life, health risk behaviors, and disability among adults with pain-related activity difficulty. Am J Public Health 2005; 95(11):2042-2048.. The relevance of proper treatment of the pain in patients with OA has been demonstrated in the study by Rodriguez-Raecke et al.⁴¹41. Rodriguez-Raecke R, Niemeier A, Ihle K, Ruether W, May A. Brain gray matter decrease in chronic pain is the consequence and not the cause of pain. J Neurosci 2009; 29(44):13746-13750.. This study found that gray matter decrease found in patients with hip OA was reversible when pain was successfully treated after a total hip arthroplasty. No similar study in TKA has been performed.

We also observed that obesity, higher BMI, was associated with higher intensity of pain. It seems that obesity contributes to chronic pain, but inactivity due to chronic pain may also lead to obesity⁴²42. Caldwell J, Hart-Johnson T, Green CR. Body mass index and quality of life: examining blacks and whites with chronic pain. J Pain 2009; 10(1):60-67.. Our results agree with previous studies where obesity had a negative impact on overall health, supporting the importance of assessing BMI in patients with chronic pain⁴²42. Caldwell J, Hart-Johnson T, Green CR. Body mass index and quality of life: examining blacks and whites with chronic pain. J Pain 2009; 10(1):60-67.. There is also a relationship between obesity and some co-morbid conditions (e.g., sleep problems)⁴³43. Vorona RD, Winn MP, Babineau TW, Eng BP, Feldman HR, Ware JC. Overweight and obese patients in a primary care population report less sleep than patients with a normal body mass index. Arch Intern Med 2005; 165(1):25-30., leading to further reduction in health-related quality of life⁴⁴44. Heo M, Allison DB, Faith MS, Zhu S, Fontaine KR. Obesity and quality of life: mediating effects of pain and comorbidities. Obes Res 2003; 11(2):209-216.. Our study would also support a relationship between these factors since several associations between the SF-36 quality of life questionnaire and sleep quality were observed in patients with TKA.

In addition, the influence of TKA in sleep and social life after long time follow-up has been described⁴⁵45. Hilding MB, Bäckbro B, Ryd L. Quality of life after knee arthroplasty. A randomized study of 3 designs in 42 patients, compared after 4 years. Acta Orthop Scand 1997; 68(2):156-160.. Subjects who had received TKA and report sleep disruptions after surgery exhibit greater disability after the surgery²⁵25. Cremeans-Smith JK, Mllington K, Sledjeski E, Greene K, Delahanty DL. Sleep disruptions mediate the relationship between early postoperative pain and later functioning following total knee replacement surgery. J Behav Med 2006; 29(2):215-222.. In fact, sleep disturbances are generally associated with chronic pain²⁰20. Martín-Herrero C, Rodrigues de Souza DP, Alburquerque-Sendín F, Ortega-Santiago R, Fernández-de-Las-Peñas C. Myofascial trigger points, pain, disability and quality of sleep in patients with chronic tension-type headache: a pilot study. Rev Neurol 2012; 55(4):193-199.

21. Muñoz-Muñoz S, Muñoz-García MT, Alburquerque-Sendín F, Arroyo-Morales M, Fernández-de-las-Peñas C. Myofascial trigger points, pain, disability, and sleep quality in individuals with mechanical neck pain. J Manipulative Physiol Ther 2012; 35(8):608-613.^-2222. Valenza MC, Valenza G, González-Jiménez E, De-la-Llave-Rincón AI, Arroyo-Morales M, Fernández-de-Las-Peñas C. Alteration in sleep quality in patients with mechanical insidious neck pain and whiplash-associated neck pain. Am J Phys Med Rehabil 2012; 91(7):584-591.^,4040. Strine TW, Hootman JM, Chapman DP, Okoro CA, Balluz L. Health-related quality of life, health risk behaviors, and disability among adults with pain-related activity difficulty. Am J Public Health 2005; 95(11):2042-2048.^,4646. Dominick KL, Ahern FM, Gold CH, Heller DA. Health-related quality of life among older adults with arthritis. Health Qual Life Outcomes 2004; 2:5.^,4747. Mäntyselkä PT, Turunen JH, Ahonen RS, Kumpusalo EA. Chronic pain and poor self-rated health. JAMA 2003; 290(18):2435-2442.. In fact, there are complex interactions between pain, fatigue, and sleep disturbances in rheumatic disorders⁴⁸48. Hakkou J, Rostom S, Mengat M, Aissaoui N, Bahiri R, Hajjaj-Hassouni N. Sleep disturbance in Moroccan patients with ankylosing spondylitis: Prevalence and relationships with disease-specific variables, psychological status and quality of life. Rheumatol Int 2013; 33(2):285-290.. In our study, the intensity of ongoing pain, disability and sleep quality were associated in individuals with TKA. Additionally, worse sleep quality can have a negative impact in cognition⁴⁹49. Camillo P, Thompson P, Goodman SB, Jiang Y. The cycle of comorbidities: potential risks with delayed joint replacement. Orthop Nurs 2013; 32(1):6-13.. Functions related to operant memory and attention can be particularly affected by sleep disturbances⁵⁰50. Orzel-Gryglewska J. Consequences of sleep deprivation. Int J Occup Med Environ Health 2010; 23(1):95-114.. It seems fairly obvious that individuals not getting sufficient sleep might have less energy during the day to be active and they report higher levels of fatigue than those with better sleep quality⁵¹51. Stebbings S, Herbison P, Doyle TC, Treharne GJ, Highton J. A comparison of fatigue correlates in rheumatoid arthritis and osteoarthritis: disparity in associations with disability, anxiety and sleep disturbance. Rheumatology (Oxford) 2010; 49(2):361-367.. Therefore, our study supports the hypothesis that sleep, emotional distress, pain intensity and disability form a continuous cycle in subjects with chronic pain.

We should recognize some limitations of our study. First, the sample size was small which may explain the lack of significance in some outcomes. It is possible that some correlacional analyses were underpowered due to the small sample size. The small sample size did not permit to conduct regression analysis to determine the interactions among the outcomes. Second, the cross-sectional nature of the study limits the interpretation of our results. Therefore, current results should be considered as preliminary.

In conclusion, this study shows that TKA experience, as an intervention applied to subjects suffering from knee OA-related pain implies a decreased physical function and worse sleep quality. The associations found between the intensity of ongoing pain, disability, sleep quality, and different domains of quality of life, as occurs with physical function, social role, mental health, vitality, and general health can help to identify the multidimensional experience of the TKA. Our results support the continuous cycle of sleep alterations, emotional distress, pain intensity, and disability in patients suffering from chronic pain. Longitudinal studies investigating the evolution of the relationships are clearly needed.

References

Publication Dates

History