Physical and psychosocial correlates of test-retest isometric torque variability in patients with chronic low back pain

Variability in trunk torque production has been suggested as a means of detecting submaximal effort in the assessment of chronic low back pain. Several investigations question the validity of using torque variability to detect submaximal efforts in patients with back injuries. However, few investigations have studied the correlates of text-retest torque variability in clinical populations. The present study investigated psychological distress, disability/flexibility/pain, and symptom magnification correlates of test-retest torque variability in chronic low back pain patients. Contrary to previous studies, psychological distress, tendency to report symptoms, and pain were negatively correlated with measures of torque variability. The findings indicate the potential for psychological variables to influence torque production, but on the whole provide little strong support for the use of test-retest torque variability as a means of detecting submaximal performance.     

Interventions to prevent back pain and back injury in nurses: a systematic review

A systematic literature review was undertaken to assess the effectiveness of interventions that aim to prevent back pain and back injury in nurses. Ten relevant databases were searched; these were examined and reference lists checked. Two reviewers applied selection criteria, assessed methodological quality and extracted data from trials. A qualitative synthesis of evidence was undertaken and sensitivity analyses performed. Eight randomised controlled trials and eight non-randomised controlled trials met eligibility criteria. Overall, study quality was poor, with only one trial classified as high quality. There was no strong evidence regarding the efficacy of any interventions aiming to prevent back pain and injury in nurses. The review identified moderate level evidence from multiple trials that manual handling training in isolation is not effective and multidimensional interventions are effective in preventing back pain and injury in nurses. Single trials provided moderate evidence that stress management programs do not prevent back pain and limited evidence that lumbar supports are effective in preventing back injury in nurses. There is conflicting evidence regarding the efficacy of exercise interventions and the provision of manual handling equipment and training. This review highlights the need for high quality randomised controlled studies to examine the effectiveness of interventions to prevent back pain and injury in nursing populations. Implications for future research are discussed.     

A comparison of isometric strength and dynamic lifting capacity in men with work-related low back injuries

Job classification, return to work status, and job placement are determined by the results of lifting capacity tests. Lifting capacity is often assessed by maximum static or dynamic physical exertions. The purpose of this study was to compare maximum isometric lifting strength with maximum dynamic lifting capacity in subjects with work-related low back injury. Twenty-seven men performed five dynamic lifting tasks and two isometric strength tests. The mean Pearson product-moment correlation between maximum isometric lifting strength measurements and maximum dynamic lifting capacity measurements was .51 with a range of .30–.73. The results indicate low to moderate associations between isometric strength measurements and lifting capacity suggesting that estimates of functional lifting capacity should not be based on static measurements alone. Dynamic lift tests are often a better simulation of the task being assessed and may be more appropriate for a back-injured population.     

The effect of lumbar support belts on isometric force production during a simulated lift

The use of back support belts by industrial workers has become common in recent years. The rationale for the use of these belts is based on the theory that they increase intra-abdominal pressure. Raised intra-abdominal pressure is believed to reduce compression forces on the spinal column and to assist the back extensor muscles in producing extension torque. The assistance of the belt is believed to protect the spine from injury. Thirty males and thirty females participated in this study which assessed the effect of two different back support belts (one synthetic and one leather) on isometric muscle-force production of individuals performing a static leg lift (SLL). A Latin Square double cross-over design was employed. Analysis of variance tests revealed that in males the use of the synthetic belt allowed for greater force production than a control trial, but no difference could be detected between the leather belt and either the synthetic belt or the control. In the female group, no difference in force production occurred across the three conditions. Implications and suggestions for further study are discussed.     

The relationship of work pace to back injury in a supermarket distribution center

This is a retrospective case control study of the relationship between work pace of selectors at a food distribution center and the subsequent incidence of compensable back injuries. Subject employment records for 1 month were evaluated for degree of variation of actual-from-scheduled performance of weekly work pace as selectors, defined in terms of absolute values (either above or below criterion). Subjects were divided among those with no compensable claims for back injury (n=14) and those with multiple compensable claims (n=12) over a 2-year period of employment. Other dependent measures included percentage of tasks that each group completed by or before the scheduled criterion and the percentage of time working that employees engaged in selector activities. The groups differed in age, averaging 38 vs. 31 years for the no claims and multiple claims groups, respectively. The groups did not differ in terms of educational background or length of service at the food distribution center. The major finding was that there was a group difference in the actual-from-scheduled, absolute mean performance values. As expected, the multiple claims group had significantly more variability in their work pace than the no claims group. The no claims group also worked significantly more often at or faster than criterion and spent, on average, a higher percentage of their day performing selector duties. These preliminary results suggest an association between work patterns and occupational injury that warrant further research, such as a clinical trial manipulating the scheduled work criterion.     

腰椎保护带对模拟驾驶人员腰部疲劳的预防作用

目的观察模拟驾驶前后驾驶员腰部疲劳情况,研究腰带对驾驶员腰部疲劳的预防作用.方法通过表面肌电图(surface electromyogram,SEMG)检测、问卷调查及体格检查观察12例受试对象在无腰带模拟驾驶前后以及佩戴腰带驾驶前后驾驶员相关指标的变化情况.结果受试对象不佩戴腰带驾驶前、后及佩戴腰带驾驶前、后表面肌电中值频谱(median frequency,MF)分别为(47.35±6.07)、(39.26±5.79)、(47.21±6.02)、(43.44±6.26)Hz,平均功率频率(mean power frequency,MPF)分别为(69.86±7.08)、(59.12±7.19)、(69.86±7.08)、(63.88±7.49)Hz,无腰带驾驶前与佩戴腰带驾驶前比较,差异无显著性(P＞0.05);无腰带驾驶前与无腰带驾驶后比较,差异有显著性(P＜0.01);佩戴腰带驾驶前与佩戴腰带驾驶后比较,差异有显著性(P＜0.01);无腰带驾驶后与佩戴腰带驾驶后比较,差异有显著性(P＜0.01).受试对象不佩戴腰带驾驶前、后及佩戴腰带驾驶前、后闪烁融合频率[(35.64±2.82)、(42.31±4.68)、(35.96±3.05)、(39.79±3.36)Hz]和明视持久度(65.77%±3.94%、56.83%±5.60%、65.88%±3.92%、62.27%±2.91%)等指标也有一定程度的变化.结论模拟驾驶一定时间后可以引起腰部肌肉的疲劳,腰带对模拟驾驶造成的腰部疲劳有一定的预防作用.     

Challenges in assessing risk factors in epidemiologic studies on back disorders

In epidemiologic studies on musculoskeletal disorders, some risk factors, especially physical load, cannot be determined independently from the worker. Posture, movement and external load are the result both of physical work requirements forced on the worker and of the worker's capacity to adopt particular techniques. Risk factors are also adjusted in relation to the worker's health. This paper presents a dynamic model that links exposure to risk factors for back pain and disability. Its aim is to help identify core elements in exposure assessment strategies for epidemiologic studies on back disorders. In this dynamic model, risk factors are determined relative to health status in order to distinguish between etiological and prognostic factors. Measurement techniques for various risk factors are classified into self-reports, observations, and direct instrumentation. Features of commonly used techniques are discussed with respect to feasibility, accuracy, and precision. In addition, consideration is given to the optimum allocation of measurements taking into account the effects of random and systematic variation in exposure due to tasks, workplaces, and workers. Am. J. Ind. Med. 32:142–152, 1997. © 1997 Wiley-Liss Inc.     

Physical capacity in relation to low back, neck, or shoulder pain in a working population

Aims

To investigate the longitudinal relation between physical capacity (isokinetic lifting strength, static endurance of the back, neck, and shoulder muscles, and mobility of the spine) and low back, neck, and shoulder pain.

Methods

In this prospective cohort study, 1789 Dutch workers participated. At baseline, isokinetic lifting strength, static endurance of the back, neck, and shoulder muscles, and mobility of the spine were measured in the pain free workers, as well as potential confounders, including physical workload. Low back, neck, and shoulder pain were self‐reported annually at baseline and three times during follow up.

Results

After adjustment for confounders, Poisson generalised estimation equations showed an increased risk of low back pain among workers in the lowest sex specific tertile of performance in the static back endurance tests compared to workers in the reference category (RR = 1.42; 95% CI 1.19 to 1.71), but this was not found for isokinetic trunk lifting strength or mobility of the spine. An increased risk of neck pain was shown for workers with low performance in tests of isokinetic neck/shoulder lifting strength (RR = 1.31; 95% CI 1.03 to 1.67) and static neck endurance (RR = 1.22; 95% CI 1.00 to 1.49). Among workers in the lowest tertiles of isokinetic neck/shoulder lifting strength or endurance of the shoulder muscles, no increased risk of shoulder pain was found.

Conclusions

The findings of this study suggest that low back or neck endurance were independent predictors of low back or neck pain, respectively, and that low lifting neck/shoulder strength was an independent predictor of neck pain. No association was found between lifting trunk strength, or mobility of the spine and the risk of low back pain, nor between lifting neck/shoulder strength or endurance of the shoulder muscles and the risk of shoulder pain.     

Factors affecting first return to work following a compensable occupational back injury

Occupational back injuries produced $27 billion in direct and indirect costs in 1988. Predictors of prolonged disability have generally been identified in selected clinical populations, but there have been few population-based studies using statewide registries from workers' compensation systems. This study uses a 1986 cohort of 8,628 Michigan workers with compensable back injuries followed to March 1, 1990. Cox proportional hazards analyses with nine categorical covariates identified factors predicting missed worktime for the first disability episode following the injury. The model distinguished factors affecting the acute (≤ 8 weeks) and chronic disability periods (> 8 weeks). The first disability episode following injury contains 69.6% of the missed worktime observed through follow-up. In the acute phase, which contributes 15.2% of first episode missed worktime, gender, age, number of dependents, industry (construction), occupation, and type of accident predict continued work disability. Marital status, weekly wage compensation rate, and establishment size do not. Beyond 8 weeks, age, establishment size and, to a lesser degree, wage compensation rate predict duration of work disability. Graphs show the predicted disability course for injured workers with specific covariate patterns. Future efforts to reduce missed worktime may require modifications in current clinical practice by patient age group and the development of new strategies to encourage small and medium-size employers to find ways to return their injured employees to work sooner. Recent federal statutes covering disabled workers will only partially correct the strong effect of employer establishment size. © 1996 Wiley-Liss, Inc.     

Determinants of occupational disability following a low back injury: a critical review of the literature

The aim of this research was to determine prognostic indicators of work disability in occupational back pain as reported in the literature, by systematically searching the research literature, assessing the methodological quality of the research, and synthesizing the findings into a concise summary. An article was considered eligible for review if research participants had an injury of the back, the article was based on original research, published in English, and involved a cohort with back pain less than 6 months post injury with at least one follow up assessment. Each article was independently reviewed by two blinded reviewers using 19 appraisal criteria for methodological quality of prognostic studies. Nineteen studies met the methodological standard to be included. Time since onset, demographic factors, functional disability, psychological distress, pain reports, previous episodes, and work environment were identified as important prognostic factors. Most studies compartmentalized the factors they considered. What is needed is a comprehensive multivariate biopsychosocial job-related model of work disability.     

A comparison of two lifting assessment approaches in patients with chronic low back pain

The Progressive Isoinertial Lifting Evaluation (PILE) and the lifting test of the WorkWell Systems Functional Capacity Evaluation (WWS) are well known as lifting performance tests. The objective of this study was to study whether the PILE and the WWS can be used interchangeably in patients with Chronic Low Back Pain (CLBP) and to explore whether psychosocial variables can explain possible differences. Methods: 53 Patients (32 men and 21 women) with CLBP were tested twice in a counter balanced design. Pearson Correlation Coefficient of r > 0.75 and non-significant differences on two-tailed t tests were considered as good comparability. Results: Pearson Correlation Coefficient was 0.75 (p < 0.01). Lifting performance on the WWS was a mean of 6.0 kg higher compared to the PILE (p < 0.01). The difference between the PILE and the WWS was unrelated to psychological variables. Conclusion: It can be concluded that the PILE and the WWS cannot be used interchangeably. Psychosocial variables cannot explain the differences between both tests.     

The reliability and validity of a measure of perceived functional capacity for work in chronic back pain

Psychosocial factors, including perceived disability and self-efficacy, are important determinants of outcome for individuals with chronic back pain. Consequently, there is a need for an evaluation and consideration of such factors in occupational rehabilitation. This study evaluated the reliability and validity of a tool, the Spinal Function Sort, as a measure of perceived capacity for work-related tasks with 42 rehabilitation clients with chronic back pain. Results provided support for the internal consistency (Cronbach's alpha of 0.97), test-rest reliability (ICC of 0.89) and construct validity of the Spinal Function Sort as a measure of perceived capacity for work-related tasks in persons with chronic back pain. Measures of similar constructs were significantly correlated with the Spinal Function Sort and were highly predictive of the Spinal Function Sort on multiple regression. Relationships between perceived work capacity and pain intensity and gender are discussed. The need for the consideration of perceived capacity in the evaluation and rehabilitation of persons with chronic back pain is highlighted.     

Design factors in epidemiologic cohort studies of work-related low back injury or pain

The connection between work-related exposures and the onset of back injury or pain is complex and not clearly understood. This paper raises design issues related to the planning and conduct of cohort studies of industrial low back pain (or injury)(LBP), with care given to definition and measurement of exposure and outcome events. These issues include sample size, outcome definition, study biases, and practical considerations when seeking and maintaining company collaboration with a research effort. Without resolving these issues, the authors conclude: (1) cohort studies of worksite-based LBP are needed to elucidate the causal associations between work tasks and LBP onset, (2) both acute and cumulative exposures should be assessed as risk factors for low back injury or pain, and (3) attention should be paid to the planning of such studies and minimization of potential biases that can limit the validity of the results. These design issues will benefit researchers and companies engaged in the planning and conduct of cohort studies of industrial LBP. Am. J. Ind. Med. 32:153–163, 1997. © 1997 Wiley-Liss Inc.     

Effect of telephone-supported ergonomic education on pregnancy-related low back pain

This study investigated the effect of telephone-supported ergonomic education on pregnancy-related low back pain. This study was performed at Trakya University Hospital in Edirne, Turkey between December 15, 2016 and April 4, 2017. One hundred ten pregnant women were included in the study and randomly assigned to one of two groups. Sixty pregnant women received one face-to-face session of ergonomic education followed by three weekly sessions of telephone-supported ergonomic education (intervention group). Fifty pregnant women received only one session of standard face-to-face ergonomic education. Before and after the intervention, low back pain was evaluated using the Visual Analog Scale. Pain-related disability was evaluated with the Oswestry Disability Index, and health-related quality of life was evaluated with the SF-36. Telephone-supported ergonomic education was more effective than standard ergonomic education and can be used as an effective solution for pregnancy-related low back pain.     

The effect of workplace based strengthening on low back injury rates: A case study in the strip mining industry

The purpose of this study was to demonstrate the effect of a once a week exercise program focused specially at lumbar extensor strengthening. This is a comparative study where workers volunteered to exercise were compared to workers who did not exercise. Low back claims for one year were noted to document efficacy of the training program. Change in strength was also noted. There was a 54% to 104% increase in strength during a 20 week program. The incidence of back injuries in the exercise group was 52 injuries per 200,000 employee hours versus the industry average of 1.09 back injuries per 200,000 employee hours. The average incidence of injury for the previous nine years at the company participating in the program was 2.94 injuries per 200,000 employee hours. The injury incidence in the workers not exercising was 2.55 injuries for 200,000 employee hours. The average workers' compensation liability dropped from $14, 430.00 per month to $380.00 per month for the study year. The significant increase in strength associated with the exercise program correlated with the greatly reduced incidence of back claims.     

Measuring low back injury risk factors in challenging work environments: an evaluation of cost and feasibility

BACKGROUND: Measuring low back injury risk factors in field research presents challenges not encountered in laboratory environments. METHODS: We compared the practical application of five measurement methods (observations, interviews, electromyography (EMG), inclinometry, and vibration monitoring) for 223 worker days in 50 heavy-industry worksites in western Canada. Data collection successes, challenges, costs, and data detail were documented for each method. RESULTS: Measurement success rates varied from 42.2% (seatpan accelerometer) to 99.6% (post-shift interview) of worker days assessed. Missed days for direct monitoring equipment were primarily due to explosive environments, workplace conditions likely to damage the equipment, and malfunctions. Costs per successful measurement day were lowest for interviews (approximately 23 dollars), about 10-fold higher for observations and inclinometry, and more than 20-fold higher for EMG and vibration monitoring. CONCLUSIONS: Costs and successful field performance need to be weighed against the added data detail gained from monitoring equipment when making choices about exposure assessment techniques for epidemiological studies.     

Barriers to patient information provision in primary care: patients' and general practitioners' experiences and expectations of information for low back pain

Background As patient involvement in health‐care increases, the role of information is crucial, especially in conditions where self‐management is considered an integral part of care. However, the suitability and applicability of much patient information has not been appraised in terms of how far it meets patients' information needs. Aims To ascertain patients' and clinicians' experiences and expectations of information in low back pain in order to suggest a suitable ‘patient‐centred’ content for a patient information pack to be used in a primary care setting. Methods A qualitative study using semi‐structured interviews with General Practitioners (GPs) (n = 15) and focus groups comprising patients with low back pain (n = 37). Results Barriers to information‐giving for low back pain in primary care exist. Patients are dissatisfied with the information they receive from their GPs, especially regarding diagnosis and treatment. Patients tend to access information from a variety of other sources, which is often contradictory, conflicts with research evidence and leads to unreasonable expectations. GPs have varying views regarding the value of patient information and are equivocal about their roles as information providers. Although The Back Book is generally acceptable as a patient information leaflet for low back pain, attention to the tone of the text is required. Conclusions Barriers exist to patient information provision, both generally and for low back pain, which need to be addressed in order to close the gap between strategy and implementation. Improving clinician communication skills and involving patients in developing information materials which meet their needs are crucial to this process.     

The social tariff of EQ-5D is not adequate to assess quality of life in patients with low back pain

Background

We compared the quality of life perceived by patients with non-specific low back pain with that predicted by the social tariff of the Spanish version of EQ-5D questionnaire.

Methods

For each health state of the EQ-5D, an adjusted tariff for patients with back pain was obtained using a linear regression model in which the linear effect of the three levels of response for each of the five domains of the EQ-5D was assumed. These coefficients were compared with those obtained for the general Spanish population. In another model, equal in structure to the standard “Dolan N” model, the linear effect of the five domains was not assumed.

Results

In 633 patients, 93 health states were recorded. Significant differences in the coefficients of self-care (p = 0.003) and the maximum level of severity in any dimension (p < 0.0001) were observed. The social tariff of the healthy population is different from the tariff of low back pain patients, with general population values being lower than those of patients, particularly in the 211 health states in which any dimension is at level 3. Weights of the different EQ-5D dimensions showed a non-linear effect on the patients’ quality of life.

Conclusion

Methods used to develop the social tariff for the Spanish version of EQ-5D were inadequate. In addition, this study shows that values given by the general population are different from those of low back pain patients, further confirming that the social tariff of EQ-5D should not be used with actual patients.     

腰腿痛患者中腰椎间盘磁共振成像局限性高信号区的分布特点及相关因素分析

目的 探讨腰腿痛患者中腰椎间盘磁共振成像(MRI)局限性高信号区(HIZ)的分布特点,并分析发生HIZ的相关因素.方法 选取2009年6月至2010年8月因腰腿痛行腰椎MRI检查的患者628例.分析HIZ在年龄、椎间盘节段和椎间盘退变中的分布特点及其相关因素.结果 628例患者3140个椎间盘中,172例(27.39％,172/628 )206个椎间盘(6.56％,206/3140)存在HIZ.其中男性患者和女性患者HIZ的发生率分别为26.38％(86/326)和28.48％( 86/302),差异无统计学意义(P=0.556).40～49岁是HIZ发生率最高的年龄段[40.22％(72/179)].椎间盘节段存在HIZ的发生率:L1～2 0.80％(5/628)、L2～3 2.07％ (13/628)、L3～42.07％(13/628)、L4～5 14.01％(88/628)、L5～S113.85％(87/628).有和无HIZ时椎间盘退变程度≥Ⅳ级者的发生率分别为49.03％( 101/206)及23.76％(697/2934),差异有统计学意义(P＜0.01).年龄、椎间盘退变程度、椎间盘节段与HIZ均具有相关性(r=-0.040,P=0.025;r=0.217,P＜0.01;r=0.179,P＜0.01).结论 腰腿痛患者中腰椎间盘MRI发生HIZ与年龄、椎间盘节段、椎间盘退变程度之间存在相关性,椎间盘退变程度是最重要的影响因素.HIZ最常发生于L4～5和L5～S1节段,40～ 49岁是高发年龄段.