Biomechanical strains and low back disorders: quantifying the effects of the number of years of exposure on various types of pain

Moving Toward Individual-Specific Automotive Seat Design: How Individual Characteristics and Time Alter the Selected Lumbar Support Prominence

OBJECTIVE

To explore how individual characteristics influence selected lumbar support prominence (LSP), seated lumbar flexion, seatback average pressure, contact area, and center of pressure (CoP) location before and after 1 hr of driving.

BACKGROUND

An LSP can alter posture and may reduce low back pain during prolonged driving. Although LSP preference varies across individuals and may change over time, few investigations have explored the time-varying response to individually selected adjustable seat parameters.

METHOD

Forty individuals selected LSP settings in an automotive seat through a series of systematic adjustment trials. The average LSP setting was fixed for a 1-hr driving simulation, followed by one final adjustment trial. Regressions were performed between individual characteristics and selected LSP, lumbar posture, and measures of seatback pressure from the initial adjustment trials. ANOVAs were performed to determine the effect of time and sex on these dependent variables. Discomfort was also monitored throughout the protocol.

RESULTS

Individual's standing lumbar lordosis, selected LSP, and height and mass were significant predictors for seated lumbar flexion, seatback average pressure, and contact area, respectively. Discomfort levels remained low; however, following the driving protocol, individuals altered their posture to decrease lumbar flexion and increase seatback average pressure without significant adjustments to the LSP.

CONCLUSION

These findings highlight individual characteristics to consider in automotive seat design and that the method for determining LSP settings may facilitate appropriate LSP selection.

APPLICATION

A systematic method to determine LSP settings may reduce discomfort and automate seat adjustments, such that only short-term postural adjustments may be required.

Low back pain among professional bus drivers: a cross-sectional study from Bangladesh

BACKGROUND

Low back pain (LBP) is a common condition contributing to impaired quality of life among professional vehicle drivers. Our study aimed to assess LBP prevalence and associated factors among professional bus drivers in Bangladesh.

METHODS

A cross-sectional study was conducted among 368 professional bus drivers using a semi-structured questionnaire. A Nordic Musculoskeletal Questionnaire (NMQ) subscale was used to measure LBP. Multivariable logistic regression analysis was used to identify the factors associated with LBP.

RESULTS

In the last month, 127 (34.51%) participants reported experiencing pain or discomfort in the lower backside. Multivariable logistic regression analysis showed that age of more than 40 years (adjusted odds ratio (aOR): 2.07, 95% confidence interval (CI): 1.14 to 3.75), the income of more than 15,000 BDT per month (aOR: 1.91, 95% CI: 1.11 to 3.26), work duration more than ten years (aOR: 2.53, 95% CI: 1.12 to 5.70), working more than 15 days per month (aOR: 1.93, 95% CI: 1.02 to 3.65), working more than 10 h per day (aOR: 2.46, 95% CI: 1.05 to 5.75), poor condition of the driving seat (aOR: 1.80, 95% CI: 1.08 to 3.02), current smoking habit (aOR: 9.71, 95% CI: 1.25 to 75.15), illicit substances use (aOR: 1.97, 95% CI: 1.11 to 3.48), and four hours or less sleeping time per day (aOR: 1.83, 95% CI: 1.09 to 3.06) were positively associated with LBP.

CONCLUSION

The high burden of LBP among the participants calls for a focus on this vulnerable group's occupational health and safety, with particular emphasis on implementing standard measures.

Occupational lower back pain and associated factors among taxi drivers in Mekelle city, north Ethiopia: a cross-sectional study

Objectives. This study aimed to assess the prevalence and associated factors of lower back pain (LBP) among taxi drivers working in Mekelle city, Tigray, Ethiopia in 2018. Methods. A community-based cross-sectional study was conducted from April to May 2018 on a sample of 294 male taxi drivers in Mekelle city, Tigray, Ethiopia. A self-administered questionnaire adapted from the Nordic musculoskeletal questionnaire was used to collect data. Independent variables that had a significant association were identified using logistic regression models. Results were reported using texts and frequency distribution tables. Results. From a total sample of 304 male drivers, 294 taxi drivers participated; hence, the response rate was 96.7%. Prevalence of self-reported LBP in the past 12 months among taxi drivers was 27.9%. Average daily hours of driving (adjusted odds ratio [AOR] 2.296, 95% confidence interval [CI] [1.194, 4.416]), using lumbar support while driving (AOR 2.075, 95% CI [1.130, 3.808]) and lack of ergonomic awareness (AOR 2.478, 95% CI [1.343, 4.575]) were significantly associated (p < 0.05) with LBP among taxi drivers. Conclusion. Prevalence of LBP in this study was more than a quarter. Average daily hours driving, use of lumbar support and ergonomics awareness were significant determinants of LBP among taxi drivers.

A thorough investigation on pushing activities in industry: The impact of the variation in the speed of motion and load conditions on initial and sustained forces

Pushing and pulling wheeled objects represent a significant part of manual material handling activities in industry. Medical investigations and epidemiological studies proved the correlation between such activities and the occurrence of lumbago, low back pain and adverse effects on the shoulders. The ISO 11228-2:2007 provides the recommended limits for pushing and pulling. Such values are the results of psychophysical studies realized under prescribed speed conditions referring to a slow walk. However, observation of real industrial and service sector environments reveals that workers are required to perform pushing activities at higher speed of motion. The aim of this study was to investigate the impact of the variation in the speed of motion and load conditions on push forces. 96 subjects performed a total of 2592 trials consisting of pushing an industrial trolley for warehouse applications, at different speed values and load conditions. Results confirm the presence of correlation between the increasing speed of motion and push forces. The findings have practical value for researchers, occupational physicians and ergonomics practitioners.

Biomechanically determined hand force limits protecting the low back during occupational pushing and pulling tasks

Though biomechanically determined guidelines exist for lifting, existing recommendations for pushing and pulling were developed using a psychophysical approach. The current study aimed to establish objective hand force limits based on the results of a biomechanical assessment of the forces on the lumbar spine during occupational pushing and pulling activities. Sixty-two subjects performed pushing and pulling tasks in a laboratory setting. An electromyography-assisted biomechanical model estimated spinal loads, while hand force and turning torque were measured via hand transducers. Mixed modelling techniques correlated spinal load with hand force or torque throughout a wide range of exposures in order to develop biomechanically determined hand force and torque limits. Exertion type, exertion direction, handle height and their interactions significantly influenced dependent measures of spinal load, hand force and turning torque. The biomechanically determined guidelines presented herein are up to 30% lower than comparable psychophysically derived limits and particularly more protective for straight pushing. Practitioner Summary: This study utilises a biomechanical model to develop objective biomechanically determined push/pull risk limits assessed via hand forces and turning torque. These limits can be up to 30% lower than existing psychophysically determined pushing and pulling recommendations. Practitioners should consider implementing these guidelines in both risk assessment and workplace design moving forward.

In the quest for degenerative lumbar spinal stenosis etiology: the Schmorl's nodes model

BACKGROUND

Degenerative lumbar spinal stenosis (DLSS) is a common health problem in the elderly and usually associated with three-joint complex degeneration. Schmorl's nodes (SNs) are described as vertical herniation of the disc into the vertebral body through a weakened part of the end plate that can lead to disc degeneration. Since SNs can harm the spine unit stability, the association between DLSS and SNs is expected. The aim of this study is to shed light on the relationship between degenerative lumbar spinal stenosis and SNs.

METHODS

Two groups of individuals were studied: the first included 165 individuals with DLSS (age range: 40-88, sex ratio: 80 M/85 F) and the second 180 individuals without spinal stenosis related symptoms (age range: 40-99, sex ratio: 90 M/90 F). The presence or absence of SNs on the cranial and caudal end plate surfaces at the lumbosacral region (from L1 to S1 vertebra) was recorded, using CT images (Brilliance 64 Philips Medical System, Cleveland Ohio, thickness of the sections was 1-3 mm and MAS, 80-250). Chi-Square test was taken to compare the prevalence of SNs between the study groups (control and stenosis) by lumbar disc level, for each gender separately. Multivariable logistic regression analysis was also used to determine the association between DLSS and SNs.

RESULTS

The prevalence rate of SNs was significantly greater in the stenosis males (L1-2 to L5-S1) and females (L4-5 and L4-S1) compared to their counterparts in the control (P < 0.001). In addition, the presence of SNs in both males and females was found to increase the likelihood for DLSS.

CONCLUSIONS

Our results indicate that SNs prevalence is significantly greater in the DLSS group compared to the control. Furthermore, SNs are strongly associated with DLSS.

Lower back pain and level of disability amongst construction workers

Abstract Introduction: Lower back pain is a symptom that significantly affects people's lives, especially workers whose professional achievements can be limited by this pain. Objective: Estimate prevalence of lower back pain and describe the levels of disability amongst construction workers. Methods: 84 construction workers participated in this study. Each of them was given three questionnaires. The first questionnaire was aimed at identifying sociodemographic variables such as work and lifestyle habits. The second questionnaire was created by Monnerat and Pereira to measure the intensity of lower back pain. The last questionnaire was created by Roland-Morris to measure functional incapacity. The SPSS 18.0 program was used for data analysis. Lower back pain was described with the Mann Whitney U test using the variables of both labor and time. Furthermore, a correlation between lower back pain intensity and functional incapacity was found by Spearman. Results: A higher prevalence of lower back pain was found (71.4%) amongst the construction workers especially during laborious activity. Time worked did not affect the prevalence of lower back pain nor did it lead to functional incapacity in workers. Conclusion: Based on all observed data, it was concluded that strenuous labor activity amongst the populace drove lower back pain prevalence.

Prevalence and risk factors of musculoskeletal disorders among Myanmar migrant workers in Thai seafood industries

A cross-sectional descriptive study was conducted with self-administered questionnaires among 368 Myanmar migrant workers to investigate the prevalence of and to determine the risk factors for musculoskeletal disorders (MSDs) in the Thai seafood industry. The results showed the prevalence of MSDs was 45.1% occurring in the last 7 days. Marital status, number of dependents, other health problems, working hours, repetitive hand movements, awkward posture of wrists, prolonged standing, and manual handling of heavy loads were found to be associated with MSDs. Multiple logistic regression indicated that the workers who were married, had more than two dependents, and had more exposure to awkward wrist postures were at significantly increased risk of MSDs. The study findings suggest the need for adequate knowledge of ergonomics and for awareness campaign programs focusing on prevention of MSDs, especially low back pain, to be initiated in industries for earlier detection of symptoms among seafood processing workers.

Is physically arduous work associated with limitations after retirement? Findings from the GAZEL cohort

INTRODUCTION

In the context of delayed retirement age, we aimed to study the association between a score for global evaluation of perceived physical strain (PPS) at work and limitations after retirement in the GAZEL cohort.

METHODS

At baseline in 1989 and every year since then, the PPS question, 'Do you find that your work is physically strenuous?' was used as a proxy measure of general occupational physical exertion or load; it was coded into a score, and divided into four categories for men and three for women. The self-report question about limitations was asked in 1989 and 2012 (difficulties performing some daily life activities). Among men and women without limitations at baseline, relationships were studied between reported limitations in 2012 and a cumulative score based on PPS since 1989, allowing examination of the dose-effect relationship, and adjusted for age and perceived state of health at baseline.

RESULTS

From 1989 to 2012, 9326 participants without limitations at baseline were followed and filled out the 2012 questionnaire. In 2012, 12.1% of men (n=845) and 12.9% of women (n=302) reported limitations. Limitations in 2012 were associated with very high categorical PPS in men (OR 1.7 (1.4 to 2.2)) and high/very high categorical PPS in women (OR 1.6 (1.2 to 2.2)), with a significant trend.

CONCLUSIONS

A positive association was found between preretirement physically arduous working conditions and limitations in daily activities after retirement. Findings offer a new insight for global evaluation of physical exposures during working life.

Biomechanical constraints remain major risk factors for low back pain. Results from a prospective cohort study in French male employees

BACKGROUND CONTEXT

Low back pain (LBP) is a major public health problem, with a considerable impact on workers.

PURPOSE

To model the risk of LBP in the male general working population.

STUDY DESIGN/SETTING

Repeated cross-sectional surveys in a wide occupational setting.

PATIENT SAMPLE

A random sample of 2,161 men working in various occupations in a French region participated in a first survey in 2002, and 1,313 of these (60.8%) participated in a second survey in 2007.

OUTCOME MEASURE

The self-reported prevalence of LBP during the previous week in the second survey.

METHODS

Twenty-one biomechanical, organizational, psychosocial, and individual factors were assessed in the first survey. The association between these potential risk factors and the prevalence of later LBP (in the second survey) was studied, using multistep logistic regression models.

RESULTS

Three hundred ninety-four men reported LBP in the second survey (prevalence 30.0%). The final multivariate model highlighted four risk factors: frequent bending (odds ratio [OR], 1.45, 95% confidence interval [CI], 1.07-1.97 for bending forward only; and OR, 2.13, 95% CI, 1.52-3.00 for bending both forward and sideways), driving industrial vehicles (OR, 1.35; 95% CI, 1.00-1.81), working more hours than officially planned (OR, 1.38; 95% CI, 1.05-1.81), and reported low support from supervisors (OR, 1.35; 95% CI, 1.02-1.79).

CONCLUSIONS

These results emphasize that biomechanical factors remain worth considering, even when psychosocial factors are taken into account, and provide a significant contribution to preventive strategies.

Cohort Profile Update: The GAZEL Cohort Study

The original GAZEL cohort was composed of 20 625 employees of the French national gas and electricity companies (15 011 male employees then aged 40 to 50 years and 5614 women between 35 and 50 years old) at its inception in 1989. A Cohort Profile article was published in 2007. By the end of 2013, participants were aged 60-75, and almost all of them retired during follow-up. Accordingly, the main focus of research in the past decade was devoted to the study of the persistent, long-term effects of occupational exposures after retirement; of the transition between professionally active life and retirement; and on determinants of early ageing. Accordingly, in addition to the health, behavioural and social data collected yearly since the beginning of the follow-up, new data were thus collected on cognitive complaints, cognitive and physical functioning, limitations in daily activities, time use and social relationships of retirees. This update presents the main findings of research within the GAZEL Cohort Study during the past 7 years. Any research group, in France or elsewhere, can submit a research proposal to work on the GAZEL cohort. To do this, interested researchers should contact one of the principal investigators of the GAZEL Cohort Study.

Occupational biomechanical exposure predicts low back pain in older age among men in the Gazel Cohort

PURPOSE

Occupational biomechanical exposures are considered as risk factors for low back pain in the working population. It has also been suggested that their effects persist after retirement. Our objectives were to assess the role of past biomechanical occupational exposure on low back pain in early old age among male participants of the Gazel Cohort.

METHODS

Low back pain for more than 30 days in the past 12 months (LBP30) was assessed in 1996 and 2006 using a French version of the Nordic questionnaire in a subsample of the Gazel Cohort. Logistic regression models were used to study associations between LBP30 in 2006 and past occupational biomechanical exposure, self-reported in 1996, taking into account personal and psychosocial work factors self-reported in 1996, and the date of retirement provided by the company. A multinomial model served to study persistent and new cases, according to LBP30 in 1996.

RESULTS

We studied 1,520 men aged 58-67 in 2006, most of them retired. Low back pain for more than 30 days in the past 12 months reported in 2006 was related to occupational biomechanical exposure encountered many years earlier (OR 1.55, 95% CI 1.05-2.27 for 10-20 years of exposure to bending/twisting, OR 1.71, 95% CI 1.17-2.49 for >20 years). These associations appeared specific to low back pain for more than 30 days in the past 12 months which persisted between 1996 and 2006.

CONCLUSION

These results suggest that occupational biomechanical exposure during active life has persistent effects among men in early old age, even for people who left the workforce. They point out the importance of preventive measures at work for better health later and appear relevant for policy-making decisions concerning age at retirement.

Effects of transfer distance on spine kinematics for de-palletizing tasks

One approach to reducing lateral bending and twisting in manual lifting tasks is to separate the lift's origin and destination, thereby encouraging lifters to step and turn their entire bodies. The objective of the current study was to determine how the degree to which one laterally bends and twists changes with transfer distance and initial lift height. Eighteen males lifted 10.9 kg boxes from a conveyor 0.5 m, 0.9 m, and 1.3 m above the floor and placed the boxes on a conveyor .50, .75, 1.00, 1.25, 1.50, or 1.75 m away at a height of .9 m. During picking, lateral bending and trunk extension velocities increased with increasing transfer distances. When placing the box, the degree of twisting decreased with increased transfer distance. In sum, when attempting to control the twisting and lateral bending during de-palletizing, the lift origin and destination should be separated by between 1 and 1.25 meters.

Biomechanical and psychosocial occupational exposures: joint predictors of post-retirement functional health in the French GAZEL cohort

OBJECTIVES

Biomechanical and psychosocial occupational exposures are seldom considered simultaneously and over extended follow-up in occupational epidemiologic studies, although there is some evidence that combined exposures have interactive effects on workers' health during working life. Given high prevalence of functional disability among retirees, research on earlier-life determinants of subsequent functional outcomes can help shape workplace policies and practices. This study investigates whether health effects of combined occupational exposures during working life are observed after individuals retire and are no longer exposed.

METHODS

Analyses were conducted among retirees in the French GAZEL occupational cohort (n=9168). Cumulative exposure during working life to eight biomechanical strains and to one or more reports of psychosocial job strain (high-demand, low-control work) were assessed as predictors of three outcomes: difficulty with physical functioning, role limitations due to physical difficulties, and bodily pain. Individuals were classified by joint exposure to both biomechanical and psychosocial constraints. We modeled risk ratios (RR) between exposure to biomechanical and psychosocial factors at work (separately and in combination) and disability after retirement, and we calculated the relative excess risk due to interaction (RERI) to test whether combined effects departed from additivity.

RESULTS

Both psychosocial and biomechanical exposures during working life were independent predictors of the three functional health outcomes. Compared with individuals who had neither biomechanical nor psychosocial exposures, in fully adjusted log-binomial models of the combined effects of biomechanical and psychosocial exposure, among those with low biomechanical exposures, the RR for physical functioning difficulties associated with psychosocial exposures was 1.18 (95% CI 1.01, 1.37). Among those with the highest levels of biomechanical exposures, RR was 1.42 (95% CI 1.21, 1.65) among those with low psychosocial exposures and 1.91 (95% CI 1.61, 2.26) among those with high psychosocial exposures. The two exposure types were modestly super-additive, with an RERI of 0.32 (95% CI 0.00, 0.62) between those with the highest and lowest levels of biomechanical exposures; if the effects were strictly additive, we would have expected an RERI of 0. For the other two outcomes results were similar, although there was no significant departure from additivity. Some effects varied in magnitude by gender.

CONCLUSION

Across the sample, combined biomechanical and psychosocial occupational exposures during working life appear to have additive or perhaps interactive effects on functional health in retirement. However, the relationship is less straightforward among women. Improving overall working conditions may lessen future disability among retirees.

Role of environmental factors and history of low back pain in sciatica symptoms among Finnish adolescents

STUDY DESIGN

Cross-sectional study in a subcohort of the 1986 Northern Finland Birth Cohort (n = 1987).

OBJECTIVE

To investigate the role of environmental factors and LBP history in sciatica symptoms among Finnish young adults.

SUMMARY OF BACKGROUND DATA

History of low back pain (LBP), smoking, and male sex are associated with sciatica in adult populations. The role of the environmental determinants of sciatica has not been evaluated in populations consisting of only adolescents.

METHODS

Sciatic symptoms and environmental exposures were elicited by a mailed questionnaire and the associations were analyzed using multinomial logistic regression.

RESULTS

Female sex was associated with severe sciatica at 18 years (OR, 3.9; 95% confidence interval (CI), 1.6-9.3). Both reported LBP at 16 years and LBP requiring consultation of a health care professional were associated with mild sciatica at 18 years (OR, 2.5; 95% CI, 1.3-4.9; and OR, 3.8; 95% CI, 1.2-11.9). In addition, LBP at 16 years requiring consultation of a health care professional was associated with severe sciatica at 18 years (OR, 5.0; 95% CI, 1.7-15.3). Smoking, obesity, physical workload, and level of physical activity were not associated with sciatica.

CONCLUSION

Females reported sciatic pain more often than males. LBP at 16 years predicted sciatica at 18 years.

LEVEL OF EVIDENCE

2.

Three components of postural control associated with pushing in symmetrical and asymmetrical stance

A number of occupational and leisure activities that involve pushing are performed in symmetrical or asymmetrical stance. The goal of this study was to investigate early postural adjustments (EPAs), anticipatory postural adjustments (APAs), and compensatory postural adjustments (CPAs) during pushing performed while standing. Ten healthy volunteers stood in symmetrical stance (with feet parallel) or in asymmetrical stance (staggered stance with one foot forward) and were instructed to use both hands to push forward the handle of a pendulum attached to the ceiling. Bilateral EMG activity of the trunk and leg muscles and the center of pressure (COP) displacements in the anterior-posterior (AP) and medial-lateral (ML) directions were recorded and analyzed during the EPAs, APAs, and CPAs. The EMG activity and the COP displacement were different between the symmetrical and asymmetrical stance conditions. The COP displacements in the ML direction were significantly larger in staggered stance than in symmetrical stance. In staggered stance, the EPAs and APAs in the thigh muscles of the backward leg were significantly larger, and the CPAs were smaller than in the forward leg. There was no difference in the EMG activity of the trunk muscles between the stance conditions. The study outcome confirmed the existence of the three components of postural control (EPAs, APAs, and CPAs) in pushing. Moreover, standing asymmetrically was associated with asymmetrical patterns of EMG activity in the lower extremities reflecting the stance-related postural control during pushing. The study outcome provides a basis for studying postural control during other daily activities involving pushing.

Effect of Handle Design on Pallet Jack Operations

Pallet jacks used in manual material handling jobs are commonly pulled behind the operator to allow full visibility, resulting in awkward shoulder extension and trunk rotation. In this laboratory study, we compared an alternative handle with a standard handle during use when traveling with the pallet jack behind the operator. Total oxygen consumption, usability, comfort, and preference were compared between the two handles. The results showed different advantages associated with each handle design, leading to the conclusion that a secondary handle, used in conjunction with a primary standard handle, may be a beneficial intervention for pallet jack use.

Socioeconomic and physical characteristics of individuals with degenerative lumbar spinal stenosis

STUDY DESIGN

A descriptive study of the association between demographic factors, and physical characteristics, and degenerative lumbar spinal stenosis (DLSS).

OBJECTIVE

To shed light on the association between socioeconomic parameters, physical characteristics, and DLSS.

SUMMARY OF BACKGROUND DATA

Lumbar spinal stenosis is a prevalent and disabling condition in the aging population. DLSS is considered to be the most common type and is essentially associated with disc disease, facet joint arthrosis, ligamentum flavum thickening, and osteophyte formation. Although there is ample information regarding the association between body mass index, cardiovascular disorders, smoking habits, and disc disease, very little is known about their association with DLSS. Data on the association of body physique (e.g., height and weight) and DLSS are limited.

METHODS

Two sample populations were studied. The first included 165 individuals with DLSS (mean age, 64 ± 9.9 yr) and the second 180 individuals without spinal stenosis related symptoms (mean age, 62.5 ± 12.6 yr). An evaluation of the cross-sectional area of the dural sac and degenerative listhesis for all participants was performed using computed tomographic lumbar spine images, obtained by Philips EBW station (Brilliance 64, Philips Medical System, Cleveland, OH). All participants were interviewed to obtain demographic, physical, and health data. Independent t test, Mann-Whitney and χ tests were used to determine the association between parametric and nonparametric variables and DLSS. Logistic regression analysis was carried out to reveal predicting variables for DLSS.

RESULTS

Females with stenosis were significantly heavier and shorter than their counterparts in the control group. We also noticed that they delivered babies more often than those in the control group. Prevalence of individuals experiencing diabetes mellitus was significantly higher in the males with stenosis than control group. In the stenosis group, the frequencies of individuals engaged in heavy manual labor (males) and housekeeping (females) were significantly higher than that of their counterparts in the control group.

CONCLUSION

Heavy manual labor and diabetes mellitus in males and housekeeping (females) play major roles in the genesis of DLSS.

Physical occupational exposures during working life and quality of life after labour market exit: results from the GAZEL study

OBJECTIVE

To investigate variations in quality of life at older ages, we take a life course perspective to analyse long-term effects of physical working conditions upon quality of life after retirement. In doing so, we study to what extent these associations are explained by individuals' health at older ages.

METHOD

We use administrative data and self-administered questionnaire responses from the French GAZEL cohort. Quality of life was assessed with CASP-19 in 2009 and related to three types of physical working conditions during previous working life: (1) ergonomic strain, (2) physical danger and (3) exposures to chemicals. Health was assessed in 2007 with the SF-36 Health Survey. Multiple regressions were calculated in retired men only, controlling for important confounders including social position.

RESULTS

In contrast to men, few women were exposed to strenuous and dangerous working conditions in this cohort and were not included in subsequent analyses. Negative effects on retired men's quality of life were found for the physical occupational exposures of ergonomic strain and physical danger, but not for chemical exposures. Effects were attenuated after the introduction of physical and mental health to the models, indicating an indirect effect of physical working conditions upon quality of life via health.

CONCLUSION

Adverse physical working conditions have long-term consequences for health and quality of life at older ages. Improvements to physical working conditions may improve individuals' quality of life over the long term.

Collaborative Care for Older Adults with low back pain by family medicine physicians and doctors of chiropractic (COCOA): study protocol for a randomized controlled trial

Background

Low back pain is a prevalent and debilitating condition that affects the health and quality of life of older adults. Older people often consult primary care physicians about back pain, with many also receiving concurrent care from complementary and alternative medicine providers, most commonly doctors of chiropractic. However, a collaborative model of treatment coordination between these two provider groups has yet to be tested. The primary aim of the Collaborative Care for Older Adults Clinical Trial is to develop and evaluate the clinical effectiveness and feasibility of a patient-centered, collaborative care model with family medicine physicians and doctors of chiropractic for the treatment of low back pain in older adults.

Methods/design

This pragmatic, pilot randomized controlled trial will enroll 120 participants, age 65 years or older with subacute or chronic low back pain lasting at least one month, from a community-based sample in the Quad-Cities, Iowa/Illinois, USA. Eligible participants are allocated in a 1:1:1 ratio to receive 12 weeks of medical care, concurrent medical and chiropractic care, or collaborative medical and chiropractic care. Primary outcomes are self-rated back pain and disability. Secondary outcomes include general and functional health status, symptom bothersomeness, expectations for treatment effectiveness and improvement, fear avoidance behaviors, depression, anxiety, satisfaction, medication use and health care utilization. Treatment safety and adverse events also are monitored. Participant-rated outcome measures are collected via self-reported questionnaires and computer-assisted telephone interviews at baseline, and at 4, 8, 12, 24, 36 and 52 weeks post-randomization. Provider-rated expectations for treatment effectiveness and participant improvement also are evaluated. Process outcomes are assessed through qualitative interviews with study participants and research clinicians, chart audits of progress notes and content analysis of clinical trial notes.

Discussion

This pragmatic, pilot randomized controlled trial uses a mixed method approach to evaluate the clinical effectiveness, feasibility, and participant and provider perceptions of collaborative care between medical doctors and doctors of chiropractic in the treatment of older adults with low back pain.

Trial registration

This trial registered in ClinicalTrials.gov on 04 March 2011 with the ID number of NCT01312233.

Effectiveness of preventive back educational interventions for low back pain: a critical review of randomized controlled clinical trials

PURPOSE

A systematic search was conducted to study the efficiency of preventive educational interventions mainly focused on a biomechanical/biomedical model.

METHODS

The PubMed electronic database and the Cochrane Library were searched based on a combination of keywords related to low back pain (LBP) and posture education. Only randomized controlled trial (RCT) studying the efficiency on outcomes directly related to LBP of a preventive intervention programme mainly based on education of proper care of the back for subjects not seeking treatment were included. References of the articles meeting these inclusion criteria were also checked to identify other potential citations. Besides, a methodological study assessment of the included RCTs was performed.

RESULTS

Nine studies, all conducted at the workplace were included in this review. Their mean quality level was low (5.1/12) and among the four studies with a huge sample size (n > 400 subjects), only one had an acceptable methodological quality score (6/12). The education interventions differed widely from one study to another. No significant differences between the control and education groups were found at the follow-up in eight out of the nine studies on the incidence of back pain, disability and sick leave.

CONCLUSIONS

The results of the RCTs included in this review suggest that educational interventions mainly focused on a biomechanical/biomedical model are not effective in preventing LBP. However, taking into account the methodological quality level of the RCTs as well as the very short and heterogeneous interventions often proposed, additional high-quality studies with a longer education period are needed to conclude that such interventions are inefficient.

Influence of automobile seat lumbar support prominence on spine and pelvic postures: a radiological investigation

BACKGROUND

The use of lumbar supports has been associated with decreased reports of low back pain during driving exposures. However, there has been limited work investigating whether lumbar supports actually change spine and pelvic postures at the level of the vertebrae.

PURPOSE

To investigate the effectiveness of a lumbar support in changing radiological measures of lumbar spine and pelvic postures and to examine the impact of support excursion magnitudes on these postures.

METHODS

Eight male subjects were recruited with no history of back injury, pathologies or low back pain within the past 6 months. Radiographs were taken in four postures: standing, and sitting with 0 cm, 2 cm and 4 cm lumbar support prominence (LSP).

RESULTS

Lumbar lordosis angle increased from 20° with no support to 25° with 2 cm support and 30° with 4 cm support. Lumbar lordosis angles were significantly different between 0 cm support and 4 cm support (p < 0.0001) and between 2 cm support and 4 cm support (p = 0.0256). Increasing lumbar support reduced the flexion at intervertebral disc joints throughout the lumbar spine, however, these remained significantly different from upright standing (p > 0.001) with the exception of L1/L2 in 4 cm support (p = 0.1381) and L5/S1 for all seated postures (p = 0.0687). All measures of pelvic posture were significantly different in sitting compared to standing (p < 0.0001), however, the lumbar support had no significant impact on seated pelvic posture.

CONCLUSIONS

Lumbar supports were shown to impact the vertebral rotations of the lumbar spine yet had no effect on pelvis postures. Increasing support from the current maximum of 2 cm-4 cm resulted in increased lumbar lordosis. The changes were mostly imparted at the upper lumbar spine joints with the most marked change being exhibited at the approximate level of the lumbar support apex: in the L2/L3 joint.

Does occupational lifting and carrying among female health care workers contribute to an escalation of pain-day frequency?

BACKGROUND

The aim of the study was to investigate if different frequencies, loads and trunk postures of occupational lifting and carrying increases the risk of sub-chronic (1-30 days last 12 months) low back pain (LBP) to become persistent (>30 days last 12 months) among female health care workers.

METHODS

Female health care workers answered a questionnaire about occupational lifting or carrying frequency (rarely, occasionally and frequently), load (low: 1-7 kg, moderate: 8-30 kg and heavy: >30 kg) and trunk posture (upright or forward bent back), and days with LBP in 2005 and 2006.

RESULTS

The odds ratio (OR) for developing persistent LBP in 2006 from these characteristics of occupational lifting and carrying was investigated with multi-adjusted logistic regressions among female health care workers with sub-chronic LBP (n = 2381) in 2005. Among health care workers with sub-chronic LBP, increased risk of persistent LBP was found from frequently lifting or carrying with forward bent back of moderate loads (OR: 1.63; 95% CI: 1.15-2.33) and heavy loads (OR: 1.56; 95% CI: 1.04-2.34). No increased risk for LBP to develop into a persistent condition was found for frequent lifting with upright back, frequent lifting or carrying of light loads, or occasionally lifting or carrying of any loads.

CONCLUSIONS

Preventive initiatives for sub-chronic LBP to develop into a persistent condition ought to focus on reducing frequent lifting and carrying of moderate and heavy loads with forward bent back.

Longitudinal associations between physical load and chronic low back pain in the general population: the Doetinchem Cohort Study

STUDY DESIGN

Prospective cohort study.

OBJECTIVE

We explored long-term associations between physical load exposure and chronic low back pain (LBP) using data from an ongoing population-based cohort study.

SUMMARY OF BACKGROUND DATA

Physical load in work or daily life is often studied in relation to LBP. Most studies are cross-sectional or have a limited follow-up.

METHODS

Between 1993 and 2007, 4738 men and women aged 25 to 64 years were measured maximal 3 times with 5-year intervals. Physical load in daily activities (9 items, e.g., awkward postures, mechanical vibration) was assessed by questionnaire at 2 measurements and chronic LBP 3 times. Physical load exposure at both measurements was described. Multivariable logistic regression analyses were adjusted for sex, age, education, work status, body mass index, physical activity, and smoking.

RESULTS

Despite stable prevalence rates of physical load exposure, about 50% of the participants exposed changed their exposure during a 5-year period. 7.2% of the participants reported awkward postures at 2 measurements, 8.4% at the first measurement only, and 6.8% at the second measurement only. Among all physical load variables, associations with chronic LBP were found only for awkward postures. An increased risk for incident chronic LBP was found in participants exposed twice to awkward postures. In contrast, only single exposure to awkward postures was associated with persistence of chronic LBP.

CONCLUSION

Awkward postures were associated with chronic LBP in the general population. Exposure to awkward postures at 2 measurements with 5 years in between did increase the risk for incident chronic LBP, but not for persistence of chronic LBP.

Low back pain around retirement age and physical occupational exposure during working life

BACKGROUND

Physical occupational exposure is a risk factor for low back pain in workers but the long term effects of exposure remain unclear. As several countries consider increasing the retirement age, further information on this topic is relevant. This study aimed to describe the prevalence of low back pain among middle aged and aging individuals in the general French population according to physical occupational exposure and retirement status.

METHODS

The study population originated from the French national survey 'Enquête décennale santé 2002'. Low back pain for more than 30 days within the previous twelve months (LBP) was assessed using a French version of the Nordic questionnaire. Occupational exposure was self assessed. Subjects were classified as "exposed" if they were currently or had previously been exposed to handling of heavy loads and/or to tiring postures. The weighted prevalence of LBP was computed separately for men and women, for active (aged 45-59) and retiree (aged 55-74), according to 5-year age group and past/present occupational exposure.

RESULTS

For active men, the prevalence of LBP was significantly higher in those currently or previously exposed (n = 1051) compared with those never exposed (n = 1183), respectively over 20% versus less than 11%. Among retired men, the prevalence of LBP tended towards equivalence with increasing age among those previously exposed (n = 748) and those unexposed (n = 599).Patterns were quite similar for women with a higher prevalence in exposed active women (n = 741) compared to unexposed (n = 1260): around 25% versus 15%. Similarly, differences between previously exposed (n = 430) and unexposed (n = 489) retired women tended to reduce with age.

CONCLUSION

The prevalence of LBP in active workers was associated with occupational exposure. The link with past exposure among retirees decreased with age. These results should be considered for policies dealing with prevention at the workplace and retirement.

Risk factors of sciatic pain: a prospective study among middle-aged employees

OBJECTIVE

To study the effects of occupational class, physical and psychosocial working conditions, health behaviours, and pain in the low back and the neck on sciatic pain among middle-aged employees.

METHODS

The participants were municipal employees without previous sciatica, aged 40, 45, 50, 55, and 60 years at baseline (n=5261, 80% women). Sciatica was defined as low back pain radiating to the calf or the foot. Data on occupational class, physical and psychosocial working conditions, body mass index, smoking, leisure-time physical activity, neck pain, local low back pain, and sciatica were obtained from baseline questionnaire surveys in 2000-2002. The question on sciatica was repeated in a follow-up survey in 2007. Logistic regression analysis was used.

RESULTS

In women, manual occupational class (OR 1.3; 95% CI 1.0-1.6 compared with managers/professionals), overweight (1.3; 1.1-1.5), obesity (1.4; 1.1-1.7), smoking (1.5; 1.2-1.7), low leisure-time physical activity (1.3; 1.0-1.7), previous acute (1.5; 1.3-1.7) and chronic (1.5; 1.1-2.0) local low back pain, and acute (1.20; 1.0-1.4) and chronic (1.5;1.2-1.9) neck pain predicted the onset of sciatica in a multivariable model. In men, semi-professionals (1.5; 1.1-2.1) and manual workers (2.0; 1.4-2.8) had an increased risk compared with managers/professionals; also acute (1.5; 1.2-2.0) and chronic (2.1; 1.2-3.9) local low back pain predicted sciatica.

CONCLUSIONS

Manual occupational class in both genders and semi-professional occupations in men, unhealthy behaviours and previous pain both in the neck and the lower back predicted sciatica, while physical and psychosocial working conditions had no independent effect.

The relationship between lumbar spine kinematics during gait and low-back pain in transfemoral amputees

OBJECTIVE

Low-back pain is an important cause of secondary disability in transfemoral amputees. The primary aim of our study is to assess the differences in lumbar spine kinematics during gait between transfemoral amputees with and without low-back pain.

DESIGN

Lumbar spine kinematics in three planes were measured when the subjects walked in a motion analysis laboratory. Nine transfemoral amputees with low-back pain, eight transfemoral amputees without low-back pain, and six healthy, nonamputee subjects participated.

RESULTS

The Amputee Pain and Amputee No Pain groups were essentially the same in terms of all demographic and potentially confounding variable measures. Transfemoral amputees with low-back pain showed greater transverse plane rotational excursion in their lumbar spine during walking when compared with transfemoral amputees without low-back pain (P = 0.029; effect size = 1.03). There were no significant differences in sagittal or coronal plane lumbar spine excursions during walking between these two groups.

CONCLUSIONS

Although our study design does not allow for proving causation, increased transverse plane rotation has been associated with intervertebral disc degeneration, suggesting that increased transverse plane rotation secondary to walking with a prosthetic limb may be a causative factor in the etiology of low-back pain in transfemoral amputees. Identifying differences in lumbar motion can lead to potential preventative and therapeutic intervention strategies.

Causal assessment of occupational carrying and low back pain: results of a systematic review

BACKGROUND CONTEXT

Occupational low back pain (LBP) is a common musculoskeletal disorder that results in high healthcare use and a heavy societal burden from morbidity and medical costs. The etiology of LBP is unclear, although numerous physical activities in the workplace have been implicated in its development. Determining the causal relationship between LBP and specific occupational activities requires a rigorous methodological approach.

PURPOSE

To conduct a systematic review of the scientific literature focused on establishing a causal relationship between occupational carrying and LBP.

STUDY DESIGN

Systematic review of the literature was performed.

SAMPLE

Studies reporting an association between occupational carrying and LBP.

OUTCOME MEASURES

Numerical association between different levels of exposure to occupational carrying and the presence or severity of LBP.

METHODS

A systematic review was performed to identify, evaluate, and summarize the literature related to establishing a causal relationship between occupational carrying and LBP by using the commonly used Bradford-Hill framework. The literature was searched using Medline, Embase, CINAHL, Cochrane Library, the Occupational Safety and Health (OSH-ROM) database, gray literature (eg, studies not published in peer-reviewed journals), hand-searching occupational health journals, reference lists of included studies, and content experts. Study quality was evaluated using a modified version of the Newcastle-Ottawa Scale. Levels of evidence supporting specific Bradford-Hill criteria were evaluated for different categories of carrying and types of LBP outcomes.

RESULTS

This search yielded 2,766 citations. A total of nine high-quality studies reported on occupational carrying and LBP, including four case-control studies and five prospective cohort studies. These nine studies reported strong and consistent evidence against a statistical association between carrying and LBP. Three studies assessed dose-response, of which only one reported a dose-response trend that was not statistically significant. Five studies were able to assess temporality, but none reported results fulfilling this aspect of causality. The biological plausibility of carrying and LBP was not discussed in any of the nine studies. None of these studies attempted to evaluate the experiment criterion by devising studies in which the exposure to carrying and level of LBP could be measured before and after implementing a strategy aimed at reducing carrying in the workplace to determine its effect on LBP.

CONCLUSIONS

This review failed to identify high-quality studies that supported any of the Bradford-Hill criteria to establish causality between occupational carrying and LBP. Based on these results, it is unlikely that occupational carrying is independently causative of LBP in the populations of workers studied.

Causal assessment of occupational bending or twisting and low back pain: results of a systematic review

BACKGROUND CONTEXT

Low back pain (LBP) is a common musculoskeletal disorder that often occurs in the working-age population. Although numerous physical activities have been implicated in its etiology, determining causation remains challenging and requires a methodologically rigorous approach.

PURPOSE

To conduct a systematic review focused on establishing a causal relationship between occupational bending or twisting and LBP.

STUDY DESIGN

A systematic review of the literature using Medline, Embase, CINAHL, Cochrane Library, and Occupational Safety and Health database, gray literature, hand-searching occupational health journals, reference lists of included studies, and experts. Evaluation of methodological quality using a modified Newcastle-Ottawa Scale for observational studies. Summary levels of evidence for each of the Bradford-Hill criteria for causality for each category of bending or twisting and type of LBP.

SAMPLE

Studies reporting an association between occupational bending or twisting and LBP.

OUTCOME MEASURES

Numerical association between different levels of exposure to bending or twisting and the presence or severity of LBP.

METHODS

A systematic review was performed to identify, evaluate, and summarize the literature related to establishing a causal relationship, according to Bradford-Hill criteria, between occupational bending or twisting and LBP.

RESULTS

This search yielded 2,766 citations. Ten high-quality studies reported on bending and LBP. Five were case-control studies and five were prospective cohort studies. There was conflicting evidence for association, with five studies demonstrating significant associations in the majority of their risk estimates, but no evidence for consistency. Seven studies assessed dose response, with four studies demonstrating a nonsignificant dose-response trend. Four studies were able to assess temporality, but only one demonstrated significant risk estimates. Biological plausibility was discussed by two studies. There was no available evidence for experiment. Seven high-quality studies reported on twisting and LBP. Two were case-control studies and five were prospective cohort studies. Three studies reported significant associations in the majority of their risk estimates, with no evidence for consistency. Three studies demonstrated a nonsignificant dose-response trend. Two studies were able to assess temporality, but only one study was able to demonstrate significant risk estimates. Two studies discussed biological plausibility. There was no available evidence for experiment.

CONCLUSIONS

A summary of existing studies was not able to find high-quality studies that satisfied more than three of the Bradford-Hill criteria for causation for either occupational bending or twisting and LBP. Conflicting evidence in multiple criteria was identified. This suggests that specific subcategories could contribute to LBP. However, the evidence suggests that occupational bending or twisting in general is unlikely to be independently causative of LBP.

Prevalence and risk factors of low back pain among Thai and Myanmar migrant seafood processing factory workers in Samut Sakorn Province, Thailand

This study assessed the prevalence of low back pain (LBP) and investigated risk factors for LBP among seafood processing factory workers in Thailand including migrant workers. The subjects were Thai and Myanmar workers in the typical seafood processing factory. A cross-sectional study was carried out with a self-administered questionnaire. Prevalence of LBP, general characteristics, life style, and working condition were investigated. The associations between LBP and risk factors were estimated by multiple logistic regression models. Of 254 workers, 165 completed the questionnaire. Half of these workers were Thai, the others were from Myanmar. The point prevalence of LBP was 28.5%. Risk factors for LBP were age over 40 yr, poor health status, history of back injury, twisting posture at work, and slipping on wet floors. The results suggest that health promotion should focus on working conditions rather than individual life style in order to prevent LBP. Furthermore, greater attention to other risk factors such as history of back injury and perception of health status after regular health check up, especially in older age groups may be needed.

Socioeconomic position and low-back pain--the role of biomechanical strains and psychosocial work factors in the GAZEL cohort

OBJECTIVE

To analyze the role that biomechanical strains and psychosocial work factors play in occupational class disparities in low-back pain in the GAZEL cohort.

METHODS

Recruited in 1989, the GAZEL cohort members were employees of the French national company in charge of energy who volunteered to enroll in an annual follow-up survey. The study population comprised 1487 men who completed questionnaires in 1996 (past occupational exposure to manual material handling, bending/twisting, and driving), 1997 (psychosocial work factors), and 2001 (low-back pain using a French version of the Nordic questionnaire for the assessment of low-back pain). Associations between low-back pain for >30 days in the preceding 12 months and social position at baseline (four categories) were described with a Cox model to determine prevalence ratios for each category. We compared adjusted and unadjusted ratios to quantify the contribution of occupational exposures.

RESULTS

The prevalence of low-back pain for >30 days was 13.6%. The prevalence of low-back pain adjusted for age was significantly higher for blue-collar workers and clerks than for managers. The number of socioeconomic disparities observed was significantly reduced when biomechanical strains were taken into account; adjusting for psychosocial factors had little impact.

CONCLUSION

In this population, occupational exposures--especially biomechanical strains--played an important role in occupational class disparities for persistent or recurrent low-back pain.

Loading along the lumbar spine as influence by speed, control, load magnitude, and handle height during pushing

BACKGROUND

Low back loading and risk associated with pushing activities have been poorly understood. Previous studies have demonstrated that increases in anterior/posterior shear forces are primarily initiated by antagonistic coactivity within the torso. Yet, few studies have considered the range of activities that might contribute to the antagonistic coactivation and subsequent spine loading.

METHODS

Twenty subjects were tested to examine how various physical factors might influence spine loads during pushing tasks that workers might experience in industrial settings. Load magnitude, speed of push, required control, and handle height were varied while pushing both carts and overhead suspended loads. A biologically-assisted biomechanical model was used to assess compression, anterior/posterior shear, and lateral shear over the various levels of the lumbar spine.

FINDINGS

Anterior/posterior shear loads were greatest at the upper levels of the lumbar spine and of a magnitude that would be of concern. Anterior/posterior shear was influenced by all experimental factors to varying degrees except for the nature of the load (cart vs. suspended).

INTERPRETATION

This study confirms the notion that pushing and pulling is not as simple a task as once believed since it entails a complex biomechanical activity. Spine shear forces result from a complex coactivation of trunk muscle activities and spine orientations that are influenced by several occupational factors. This study may help explain why low back pain rates in some work environments associated with lifting may not be reduced even when lifting interventions (that change the task from lifting to pushing) are employed.