Biomechanical and psychosocial risk factors for low back pain at work

Wearable Motion Analysis System for Thoracic Spine Mobility With Inertial Sensors

This study presents a wireless wearable portable system designed for the automatic quantitative spatio-temporal analysis of continuous thoracic spine motion across various planes and degrees of freedom (DOF). This includes automatic motion segmentation, computation of the range of motion (ROM) for six distinct thoracic spine movements across three planes, tracking of motion completion cycles, and visualization of both primary and coupled thoracic spine motions. To validate the system, this study employed an Inter-days experimental setting to conduct experiments involving a total of 957 thoracic spine movements, with participation from two representatives of varying age and gender. The reliability of the proposed system was assessed using the Intraclass Correlation Coefficient (ICC) and Standard Error of Measurement (SEM). The experimental results demonstrated strong ICC values for various thoracic spine movements across different planes, ranging from 0.774 to 0.918, with an average of 0.85. The SEM values ranged from 0.64° to 4.03°, with an average of 1.93°. Additionally, we successfully conducted an assessment of thoracic spine mobility in a stroke rehabilitation patient using the system. This illustrates the feasibility of the system for actively analyzing thoracic spine mobility, offering an effective technological means for non-invasive research on thoracic spine activity during continuous movement states.

Work as a social determinant of health in high-income countries: past, present, and future

This paper, the first in a three-part Series on work and health, provides a narrative review of research into work as a social determinant of health over the past 25 years, the key emerging challenges in this field, and the implications of these challenges for future research. By use of a conceptual framework for work as a social determinant of health, we identified six emerging challenges: (1) the influence of technology on the nature of work in high-income countries, culminating in the sudden shift to telework during the COVID-19 pandemic; (2) the intersectionality of work with gender, sexual orientation, age, race, ethnicity, migrant status, and socioeconomic status as codeterminants of health disparities; (3) the arrival in many Organisation for Economic Co-operation and Development countries of large migrant labour workforces, who are often subject to adverse working conditions and social exclusion; (4) the development of precarious employment as a feature of many national labour markets; (5) the phenomenon of working long and irregular hours with potential health consequences; and (6) the looming threat of climate change's effects on work. We conclude that profound changes in the nature and availability of work over the past few decades have led to widespread new psychosocial and physical exposures that are associated with adverse health outcomes and contribute to increasing disparities in health. These new exposures at work will require novel and creative methods of data collection for monitoring of their potential health impacts to protect the workforce, and for new research into better means of occupational health promotion and protection. There is also an urgent need for a better integration of occupational health within public health, medicine, the life sciences, and the social sciences, with the work environment explicitly conceptualised as a major social determinant of health.

Severity of slouched posture during smartphone use is associated with the musculoskeletal discomfort, daily usage, and school year among adolescents

Real-time measurement of the craniovertebral, thoracic kyphosis, and lumbar lordosis angles during natural and smartphone usage postures in sitting were analysed in a cohort of 560 adolescents using independent t-tests and Spearman's correlations between their reported musculoskeletal symptoms, daily device use and school year. Students with musculoskeletal symptoms (mean difference: 4.1-9.4°, p < .001) and in secondary schools (mean difference: 13.6-29.4°, p < .001) had a greater forward-head posture quantified by craniovertebral angle in both postures. Loss of lumbar lordosis was found in students spending ≥2 h/day on electronic devices (mean difference: 3.2°, p = .029) and those with musculoskeletal symptoms (mean difference: 5.4°, p = .001). Secondary school students exhibited a greater thoracic kyphosis when using smartphones (mean difference: 3.3°, p = .003). Findings suggest the urgent need for early and proactive intervention targeted to minimise the risk of developing musculoskeletal disorders related to intense device use for young adolescents.Practitioner Summary: Adolescents: (1) in higher school year had increased forward-head posture (FHP) and thoracic kyphosis; (2) with musculoskeletal symptoms had increased FHP and loss of lumbar lordosis, and; (3) with extended device use had a loss of lumbar lordosis. Early intervention targeting young adolescents promoting optimal posture and habit of device use is warranted.

Occupational factors and low back pain: a Mendelian randomization study

Background

Low back pain (LBP) is a common condition and a leading cause of health function loss worldwide. This study assessed the impact of occupational factors on LBP using Mendelian Randomization (MR) method, controlling for confounding variables.

Methods

Based on publicly available genome-wide association studies (GWAS), two-sample univariate and multivariate MR analyses were performed to assess the causal effect of occupational factors on LBP. We used the inverse variance weighted (IVW) method and sensitivity analyses to generate the total results for the univariate MR analysis. Furthermore, we performed multivariate MR analysis to assess the direct causal association between occupational factors and LBP after accounting for potential confounding variables.

Results

The total causal effect of genetically predicted job involves heavy manual or physical work on LBP was found to be significant (IVW OR, 2.117; 95% CI, 1,288-3.479; p = 0.003). Upon adjusting for potential confounding variables, the direct effect of job involves heavy manual or physical work on LBP remained statistically significant. Similarly, the total causal effect of genetically predicted job involves mainly walking or standing on LBP was also found to be significant (IVW OR, 1.429; 95% CI, 1,035-1.975; p = 0.030). However, upon adjusting for potential confounding variables, the direct effect of job involves mainly walking or standing on LBP became insignificant. In contrast, the findings from the MR analysis indicated a lack of association between work/job satisfaction and LBP. Sensitivity analysis consistently supported these trends.

Conclusion

Our results supported a causal link between job involves heavy manual or physical work and increased risk of LBP, while finding no significant associations between prolonged walking/standing at work, job satisfaction, and LBP, providing valuable insights for the development of targeted prevention and intervention strategies for LBP.

Influence of load knowledge on lifting biomechanics

Objectives. Findings from previous studies implied that appropriately controlling load knowledge might help improve the biomechanical performance during lifting tasks. However, only load weight knowledge was often discussed in previous studies. The current study aimed to complement the existing studies and provide improved knowledge about the influence of load knowledge on lifting biomechanics. Methods. Twenty-four healthy male participants were recruited and instructed to perform symmetric lifting tasks with different load weights under different load knowledge conditions. Load weights were set at three levels (40, 80 and 120%) of each participant's maximum acceptable lifting capacity. The examined load knowledge conditions included 'no knowledge' condition, 'weight known' condition, 'fragile material known' condition and 'weight and fragile material known' condition. Results. We found that when knowing fragility information about lifting materials, workers tended to be more cautious by adopting a less dynamic motion pattern during the landing phase, as evidenced by decreases of 6-8% in elbow joint acceleration. The 'cautious' lifting pattern when fragility load knowledge was presented could contribute to reduced risk of lower back disorder. Conclusion. This finding could help to develop lower back disorder prevention interventions to improve occupational safety and health.

Interaction between physical demands and job strain on musculoskeletal symptoms and work performance

This study investigated the interaction between physical demands and job strain on musculoskeletal symptoms in upper extremities (MSUE) and work performance. Two years of prospective data were analysed from 713 full-time workers from twelve manufacturing and healthcare facilities in Washington in the United States. Physical exposure was measured by the Strain Index and Threshold Limit Value for hand activity, giving rise to safe, action, and hazardous physical demand groups. Job strain was calculated as the ratio of psychological job demands to job control. Multilevel modelling analysis showed that job strain affected MSUE and limited work performance less in the high physical demand group than the safe group because the protective effect of job control was smaller in these groups. Findings may suggest that high physical demand jobs are structured such that workers have low job control or high physical demand groups experience job strain not adequately captured by psychosocial variables.Practitioner Summary: The effects of job strain and job control on musculoskeletal symptoms in upper extremities and work performance were smaller among workers with higher physical demands. This could imply that high physical demand jobs limit job control or psychosocial variables may not adequately capture job strain among high physical demand groups.

Sport and non-specific low back pain in athletes: a scoping review

BACKGROUND

The contribution of sport in non-specific low back pain (NS-LBP) remains unknown, due to a large heterogeneity in the methods applied in research. The aims of this scoping review (ScR) were to systematically map and summarize findings concerning studies reporting data on NS-LBP among athletes.

METHODS

This ScR was developed referring to the 2020 version of the "Joanna Briggs Institute Methodological Guidance" and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews. Five medical databases (Pubmed, Cochrane, Central, Embase, Pedro and Scopus) were searched up to November 2021. No limitations in terms of study design and language were applied. Results were presented numerically and thematically.

RESULTS

A total of 4061 records were identified through the initial search; 114 articles met the inclusion criteria. Publications have increased over the years, since 1990. Most of the studies were conducted in the USA (17.5%), even if most research was conducted in Europe (53.5%). Analytic observational (42%) and cross-sectional studies (37%) were the most used designs, followed by case reports (12%) and systematic reviews (9%). Boating (7%), football, soccer, volleyball, running and gymnastics (4.4% each) were the most investigated, although the majority of the studies considered sports in general (36.8%). The overall sample size median was 181, mean age 22 ± 10.2; 68% of athletes were professional and 32% amateur. Most of the studies (38%) did not detail the frequency of training. Sport was reported as a risk factor for developing NS-LBP in 67.5% of cases, especially in those studies which assessed activities implying high or repeated loading on the spine.

CONCLUSIONS

This is the first ScR to provide a comprehensive overview on this topic. The increased number of publications on the association between sport practice and NS-LBP demonstrates a growing interest over the years on this topic. Some sport activities seem to be more involved than others in LBP development; however, research methods are extremely varied, thus more standardized observational research may focus on specific disciplines to properly contribute to research and clinical practice.

The Validity and Inter-Rater Reliability of a Video-Based Posture-Matching Tool to Estimate Cumulative Loads on the Lower Back

BACKGROUND

Low back pain (LBP) is known as one of the most common work-related musculoskeletal disorders. Spinal cumulative loads (CLs) during manual material handling (MMH) tasks are the main risk factors for LBP. However, there is no valid and reliable quantitative lifting analysis tool available for quantifying CLs among Iranian workers performing MMH tasks.

OBJECTIVE

This study aimed to investigate the validity and inter-rater reliability of a posture-matching load assessment tool (PLAT) for estimating the L5-S1 static cumulative compression (CC) and shear (CS) loads based on predictive regression equations.

MATERIAL AND METHODS

This experimental study was conducted among six participants performing four lifting tasks, each comprised of five trials during which their posture was recorded via a motion capture (Vicon) and simultaneously a three-camera system located at three different angles (0°, 45°, and 90°) to the sagittal plane.

RESULTS

There were no significant differences between the two CLs estimated by PLAT from the three-camera system and the gold-standard Vicon. In addition, ten raters estimated CLs of the tasks using PLAT in three sessions. The calculated intra-class correlation coefficients for the estimated CLs within each task revealed excellent inter-rater reliability (> 0.75), except for CS in the first and third tasks, which were good (0.6 to 0.75).

CONCLUSION

The proposed posture-matching approach provides a valid and reliable ergonomic assessment tool suitable for assessing spinal CLs during various lifting activities.

Estimating Trunk Angle Kinematics During Lifting Using a Computationally Efficient Computer Vision Method

OBJECTIVE

A computer vision method was developed for estimating the trunk flexion angle, angular speed, and angular acceleration by extracting simple features from the moving image during lifting.

BACKGROUND

Trunk kinematics is an important risk factor for lower back pain, but is often difficult to measure by practitioners for lifting risk assessments.

METHODS

Mannequins representing a wide range of hand locations for different lifting postures were systematically generated using the University of Michigan 3DSSPP software. A bounding box was drawn tightly around each mannequin and regression models estimated trunk angles. The estimates were validated against human posture data for 216 lifts collected using a laboratory-grade motion capture system and synchronized video recordings. Trunk kinematics, based on bounding box dimensions drawn around the subjects in the video recordings of the lifts, were modeled for consecutive video frames.

RESULTS

The mean absolute difference between predicted and motion capture measured trunk angles was 14.7°, and there was a significant linear relationship between predicted and measured trunk angles (R² = .80, p < .001). The training error for the kinematics model was 2.3°.

CONCLUSION

Using simple computer vision-extracted features, the bounding box method indirectly estimated trunk angle and associated kinematics, albeit with limited precision.

APPLICATION

This computer vision method may be implemented on handheld devices such as smartphones to facilitate automatic lifting risk assessments in the workplace.

Influence of Load Knowledge on Biomechanics of Asymmetric Lifting

BACKGROUND

Load knowledge has been identified as a factor affecting the risk of low back pain (LBP) during symmetric lifting. However, the effects of load knowledge in asymmetric lifting tasks have not been reported yet. The purpose of this study was to investigate the load knowledge influence on lifting biomechanics in asymmetric lifting tasks; Methods: Twenty-four male adults were recruited to complete a psychophysical lifting capacity test and a simulated asymmetric lifting task. The lifting task was set with load knowledge of 'no knowledge' (NK), 'weight known' (WK), 'fragile material known' (FK), and 'weight and fragile material known' (WFK) for different lifting load weights. Trunk kinematics and kinetics were collected and analyzed; Results: When fragility information was presented, trunk sagittal flexion acceleration, lateral flexion velocity and acceleration, and average lateral bending moment were significantly lowered at the deposit phase. Lifting a high load weight was found to significantly increase low back sagittal bending moment at the lifting phase and low back moments of all three dimensions at the deposit phase; Conclusions: The decrease of trunk kinematic load suggests that providing material fragility information to workers in asymmetric lifting tasks would be effective in reducing their risk of LBP.

Application of Wearable Sensors Technology for Lumbar Spine Kinematic Measurements during Daily Activities following Microdiscectomy Due to Severe Sciatica

Simple Summary

The recurrence rate after lumbar spine disc surgeries is estimated to be 5–15%. Lumbar spine flexion of more than 10° is mentioned in the literature as the most harmful load to the operated disc level that could lead to recurrence during the first six postoperative weeks. The purpose of this study is to quantify flexions during daily living following such surgeries, for six weeks postoperatively, using wearable sensors technology. These data determine the patients’ kinematic pattern, reflecting a high-risk factor for pathology recurrence. The operated patients were measured to have 30% normal lumbar motion after the first postoperative week, while they were restored to almost 75% at the end of the sixth, respectively. Further in vitro studies should be carried out using these data to identify if such kinematic patterns could lead to pathology recurrence.

Abstract

Background: The recurrence rate of lumbar spine microdiscectomies (rLSMs) is estimated to be 5–15%. Lumbar spine flexion (LSF) of more than 10° is mentioned as the most harmful load to the intervertebral disc that could lead to recurrence during the first six postoperative weeks. The purpose of this study is to quantify LSFs, following LSM, at the period of six weeks postoperatively. Methods: LSFs were recorded during the daily activities of 69 subjects for 24 h twice per week, using Inertial Measurement Units (IMU). Results: The mean number of more than 10 degrees of LSFs per hour were: 41.3/h during the 1st postoperative week (P.W.) (29.9% healthy subjects-H.S.), 2nd P.W. 60.1/h (43.5% H.S.), 3rd P.W. 74.2/h (53.7% H.S.), 4th P.W. 82.9/h (60% H.S.), 5th P.W. 97.3/h (70.4% H.S.) and 6th P.W. 105.5/h (76.4% H.S.). Conclusions: LSFs constitute important risk factors for rLDH. Our study records the lumbar spine kinematic pattern of such patients for the first time during their daily activities. Patients’ data report less sagittal plane movements than healthy subjects. In vitro studies should be carried out, replicating our results to identify if such a kinematic pattern could cause rLDH. Furthermore, IMU biofeedback capabilities could protect patients from such harmful movements.

Prevalence of Low Back Pain and Associated Risk Factors among Farmers in Jeju

Background

We aimed to investigate the prevalence of low back pain (LBP) and its associated agricultural work-related, biomechanical factors among this population.

Methods

We analyzed initial survey data from the Safety for Agricultural Injury of Farmers cohort study involving adult farmers in Jeju Island. The prevalence of LBP was calculated with associated factors.

Results

In total, 1,209 participants were included in the analysis. The overall prevalence of LBP was 23.7%. Significant associations for LBP were the type of farming activity, length of farming career, prior agricultural injury within 1 year, and stress levels. Multivariate logistic regression analysis revealed three biomechanical factors significantly related to LBP: repetitive use of particular body parts; the inappropriate posture of the lower back and neck.

Conclusions

Some occupational, and biomechanical risk factors contribute to LBP. Therefore, postural education, injury prevention education, and psychological support will be needed to prevent LBP.

A pilot study to assess a risk of a high-risk group of low back pain membership in workers who perform the manual material handling tasks

BACKGROUND

We conducted this experimental study to estimate a risk of a high-risk group of low back pain (LBP) membership in workers who perform the manual material handling (MMH) tasks in an actual workplace setting.

METHODS

The subjects include healthy workers who were engaged in 12 MMH tasks at 6 manufacturing companies. We assessed the dynamic motion of trunk or lumbar spine using an industrial lumbar motion monitor (BioDynamics Laboratory of Ohio State University). The subjects were evaluated for the age, gender, years of working and anthropometric measurements (e.g., height, weight, shoulder height, elbow height, iliac height, leg length, trunk length, trunk circumference, iliac width, iliac depth, xiphoid width and xiphoid depth). Moreover, they were also evaluated for a risk of a high-risk group of LBP membership based on lift frequency, average twisting velocity, maximum moment, maximum sagittal flexion and maximum lateral velocity.

RESULTS

The subjects who were engaged in a packaging at a detergent manufacturing company are at the greatest risk of LBP (63.76%). This was followed by packaging at a leather product manufacturing company (57.06%), packaging at a non-metallic casting material manufacturing company (57.03%), manual injection at a non-metallic casting material manufacturing company (52.00%), toggling at a leather product manufacturing company (46.09%), non-metallic casting material manufacturing company (42.88%), rolling at a non-metallic mineral product manufacturing company (42.12%), shooting at a non-metallic casting material manufacturing company (40.99%), vacuum processes at a leather product manufacturing company (35.00%), looping at a general industrial machinery manufacturing company (33.93%), setting at a leather product manufacturing company (30.22%) and packaging at a general metal product manufacturing company (22.02%).

CONCLUSIONS

Our approach indicates that there is a risk of a high-risk group of LBP membership in workers who perform the MMH tasks.

Contributions of Ergonomics, Psychological Factors, and Sleep Disturbances to Lower Back Pain Among Taiwanese Workers

OBJECTIVE

We investigated the contributions of ergonomics, psychological factors, and sleep disturbances to lower back pain (LBP).

METHODS

A nationwide survey of sampled 27,508 (2.6‰) Taiwanese workers was conducted in 2010. Definition of outcome was LBP affecting work performance in the past year. Predictor variables included age, body mass index, ergonomic factors, job control, psychological demands, and sleep disturbances. Mutually adjusted relative risks were examined using general linear models, followed by aPAR.

RESULTS

18,353 workers were included in the multivariate regression model. The three first significant risk factors to LBP included heavy lifting or awkward posture, sleep disturbances, and high psychological demands (aPAR = 13.5%, 8.7%, 5.7% respectively in men and 6.1%, 11.8%, 5.9% in women).

CONCLUSIONS

In addition to ergonomic exposure, sleep disturbances and high psychological demands significantly contributed to LBP.

Spinal and Pelvic Alignment of Sitting Posture Associated with Smartphone Use in Adolescents with Low Back Pain

This study aimed to assess the association between smartphone use in the sitting posture and changes in thoracolumbar kyphosis, lumbar lordosis, and pelvic asymmetry in adolescents with low back pain (LBP). Twenty-five adolescents with LBP and 25 healthy adolescents participated in this study. They were instructed to sit on a height-adjustable chair with their hips and knees bent at 90° for 30 min in their usual sitting postures. Thoracolumbar kyphosis, lumbar lordosis, and pelvic asymmetry were measured using a three-dimensional motion capture system. Thoracolumbar kyphosis and lumbar lordosis increased after 30 min of sitting compared to the baseline. In both groups, thoracic kyphosis and lumbar lordosis angle increased with increasing sitting time. Compared to healthy adolescents, adolescents with LBP presented greater thoracolumbar kyphosis and lumbar lordosis after prolonged sitting. Pelvic asymmetry showed no significant difference between the sitting time and groups. Using a smartphone during prolonged sitting may lead to a slumped posture; these associations were more pronounced in adolescents with LBP.

Minimizing Low Back Cumulative Loading during Design of Manual Material Handling Tasks: An Optimization Approach

OCCUPATIONAL APPLICATIONSWe present a practical method for minimizing low-back cumulative loading that leverages digital human modeling capabilities and optimization using an evolutionary algorithm. We demonstrate use of the method in a simulated lifting task. Our results show that this method is robust to different routines for calculating cumulative loading. The proposed method can aid ergonomics engineers in addressing a potential risk factor early in the design stage, even in the absence of an established threshold limit value, and it provides a time saving by eliminating the need to adjust workplace parameters across many design possibilities.

Low Back Pain and Associated Factors among Hairdressers in Northern Ethiopia: A Cross-Sectional Study

Low back pain is one of the major occupational health problems ranked the highest in terms of years lived with disability, and it has an economic burden on individuals and society in general. Hairdressers are high-risk professionals, but they are usually getting less attention in research and policy actions. The objective of this study is to assess the magnitude and associated factors of low back pain among hairdressers working in female beauty salons of Mekelle, Northern Ethiopia. A cross-sectional study was employed from January up to March 2018. A simple random sampling was applied to select 344 participants. Interviewer-administered, pretested, and structured questionnaire was used. Bivariate and multivariate binary logistic regression analyses were performed using SPSS version 23. A p value of <0.05 was used to declare statistical significance. A total of 314 hairdressers participated, with a 91.3% response rate. The study found that the prevalence of low back pain was 47.5% with 95% CI (41.8-53.1). Marital status (AOR: 0.40, 95% CI (0.23-0.71)), awkward posture (AOR: 2.59, 95%CI (1.45-4.63)), working greater than 4 days in a week (AOR: 5.12, 95% CI (1.94-13.70)), the task of washing the client's hair (AOR: 4.45, 95% CI (1.93-10.26)), having adjustable washing basin (AOR: 0.35, 95% CI (0.18-0.69)), job stress (AOR: 0.45, 95% CI (0.27-0.77)), and job satisfaction (AOR: 0.58, 95% CI (0.34-0.98)) were factors that show a statistically significant association with low back pain. This study found that low back pain is a major health problem among hairdressers. Marital status, awkward postures, working days per week, the task of washing the client's hair, adjustable washing basin, job stress, and job satisfaction show a strong association with low back pain. The result suggests that effective intervention strategies for low back pain need to include ergonomic improvements and psychosocial and behavioral aspects of the participants.

Feature Detection and Biomechanical Analysis to Objectively Identify High Exposure Movement Strategies When Performing the EPIC Lift Capacity test

Purpose The Epic Lift Capacity (ELC) test is used to determine a worker's maximum lifting capacity. In the ELC test, maximum lifting capacity is often determined as the maximum weight lifted without exhibiting a visually appraised "high-risk workstyle." However, the criteria for evaluating lifting mechanics have limited justification. This study applies feature detection and biomechanical analysis to motion capture data obtained while participants performed the ELC test to objectively identify aspects of movement that may help define "high-risk workstyle". Method In this cross-sectional study, 24 participants completed the ELC test. We applied Principal Component Analysis, as a feature detection approach, and biomechanical analysis to motion capture data to objectively identify movement features related to biomechanical exposure on the low back and shoulders. Principal component scores were compared between high and low exposure trials (relative to median exposure) to determine if features of movement differed. Features were interpreted using single component reconstructions of principal components. Results Statistical testing showed that low exposure lifts and lowers maintained the body closer to the load, exhibited squat-like movement (greater knee flexion, wider base of support), and remained closer to neutral posture at the low back (less forward flexion and axial twist) and shoulder (less flexion and abduction). Conclusions Use of feature detection and biomechanical analyses revealed movement features related to biomechanical exposure at the low back and shoulders. The objectively identified criteria could augment the existing scoring criteria for ELC test technique assessment. In the future, such features can inform the design of classifiers to objectively identify "high-risk workstyle" in real-time.

Low Back Pain (LBP), work and absenteeism

BACKGROUND

Occupational physical demands are commonly assumed the cause of work-related Low Back Pain (LBP) and absenteeism.

OBJECTIVES

To analyse relationships between LBP at work, physical demands and absenteeism.

METHODS

Workers filled out a questionnaire on socio-demographic and work-related factors, general health, LBP (number of episodes in a 12-month period, pain severity and intensity), and occupational hazards related with physical demands.

RESULTS

735 workers completed the questionnaire (male n = 359). A high proportion of workers n = 507 (69%), from different occupational backgrounds, reported at least one LBP episode in the previous 12-month period. The highest ratio of subjects with more than 6 episodes of LBP per year was found among public services employees (31.8%) and the lowest ratio among administrative workers (10.3%). The highest ratio of workers (39%) were classified as sedentary workers, 34% of workers having a low or moderate level of physical demands in their work, and 27% reported high levels of physical demands in their work. There was a 4 % absenteeism rate in a 12-month period, which was significantly higher in the group with physically demanding work. Those subjects with higher physical requirements at work have increased odds of having more than 3 episodes of LBP during the previous year (p < 0.05) in comparison with subjects with more sedentary jobs and those with low or moderate physical demands. High intensity work, compared to sedentary work, is associated with an increased probability of being absent of work because of LBP in a previous 12-month period (OR = 3.12; CI 1.23-7.89; p = 0.016).

CONCLUSIONS

Our findings suggest there is an association between highly physically demanding jobs, LBP and absenteeism. These results may contribute to the improvement of LBP assessment and prevention programs in Occupational Health Services.

Analysis of Motor Control in Patients With Low Back Pain: A Key to Personalized Care?

Motor control exercise has been shown to be effective in the management of low back pain (LBP). However, the effect sizes for motor control exercise are modest, possibly because studies have used a one-size-fits-all approach, while the literature suggests that patients may differ in presence or type of motor control issues. In this commentary, we address the question of whether consideration of such variation in motor control issues might contribute to more personalized motor control exercise for patients with LBP. Such an approach is plausible, because motor control changes may play a role in persistence of pain through effects on tissue loading that may cause nociceptive afference, particularly in the case of peripheral sensitization. Subgrouping systems used in clinical practice, which comprise motor control aspects, allow reliable classification that is, in part, aligned with findings in studies on motor control in patients with LBP. Motor control issues may have heuristic value for treatment allocation, as the different presentations observed suggest different targets for motor control exercise, but this remains to be proven. Finally, clinical assessment of patients with LBP should take into account more aspects than motor control alone, including pain mechanisms, musculoskeletal health, and psychosocial factors, and may need to be embedded in a stratification approach based on prognosis to avoid undue diagnostic procedures. J Orthop Sports Phys Ther 2019;49(6):380-388. Epub 12 Jun 2018. doi:10.2519/jospt.2019.7916.

Prevalence and Work-Related Factors Associated with Lower Back Musculoskeletal Disorders in Female Shellfish Gatherers in Saubara, Bahia-Brazil

Lower back musculoskeletal disorders (MSDs) are an important public health problem and the leading cause of disability worldwide, but with yet unknown prevalence among shellfish gatherers. To investigate the prevalence and work-related factors associated with lower back MSD in a population of female shellfish gatherers, an epidemiological cross-sectional study was carried out in Saubara, Bahia-Brazil, in 2013. The Brazilian version of the Job Content Questionnaire (JCQ) and the Nordic Musculoskeletal Questionnaire (NMQ), in addition to a questionnaire containing the physical demands adapted to the artisanal work, were applied to a random sample of 209 female shellfish gatherers. The prevalence of lower back MSD was 72.7%. Using multivariate logistic regression, the shellfish gatherers who had worked for more than 26 years in the activity showed a prevalence of 1.22 (95% CI: 1.04–1.44) times higher compared to those unexposed. Lower back MSD was 1.24 (95% CI: 1.08–1.42) times higher among those more exposed to work sitting with trunk flexion. Those performed manual handling and muscle force with the arms had a prevalence ratio of 1.18 (95% CI: 1.01–1.39). These results show the need for greater awareness of health and social welfare factors impacting workers in small-scale fisheries and will promote the elaboration of health care policies for this occupational class.

Predicting Sagittal Plane Lifting Postures From Image Bounding Box Dimensions

OBJECTIVE

A method for automatically classifying lifting postures from simple features in video recordings was developed and tested. We explored if an "elastic" rectangular bounding box, drawn tightly around the subject, can be used for classifying standing, stooping, and squatting at the lift origin and destination.

BACKGROUND

Current marker-less video tracking methods depend on a priori skeletal human models, which are prone to error from poor illumination, obstructions, and difficulty placing cameras in the field. Robust computer vision algorithms based on spatiotemporal features were previously applied for evaluating repetitive motion tasks, exertion frequency, and duty cycle.

METHODS

Mannequin poses were systematically generated using the Michigan 3DSSPP software for a wide range of hand locations and lifting postures. The stature-normalized height and width of a bounding box were measured in the sagittal plane and when rotated horizontally by 30°. After randomly ordering the data, a classification and regression tree algorithm was trained to classify the lifting postures.

RESULTS

The resulting tree had four levels and four splits, misclassifying 0.36% training-set cases. The algorithm was tested using 30 video clips of industrial lifting tasks, misclassifying 3.33% test-set cases. The sensitivity and specificity, respectively, were 100.0% and 100.0% for squatting, 90.0% and 100.0% for stooping, and 100.0% and 95.0% for standing.

CONCLUSIONS

The tree classification algorithm is capable of classifying lifting postures based only on dimensions of bounding boxes.

APPLICATIONS

It is anticipated that this practical algorithm can be implemented on handheld devices such as a smartphone, making it readily accessible to practitioners.

The effect of sitting posture on the loads at cervico-thoracic and lumbosacral joints

BACKGROUND:

The sitting in an awkward posture for a prolonged time may lead to spinal or musculoskeletal disease. It is important to investigate the joint loads at spine while sitting.

OBJECTIVE:

The purpose of this study was to investigate the joint moment and antero-posterior (AP) reaction force at cervico-thoracic and lumbosacral joint for various sitting postures.

METHODS:

Twenty healthy males participated in this study. Six sitting postures were defined from three spinal curvatures (slump, flat, and lordosis) and two arm postures (arms-on-chest and arms-forward). Kinematic and kinetic data were measured in six sitting postures from which joint moment and AP reaction force were calculated by inverse dynamics.

RESULTS:

In the cervico-thoracic joint, joint moment and AP reaction force were greater in slump than the flat and lordosis postures (p< 0.001) and also in arms-forward posture compared to arms-on-chest posture. In the lumbosacral joint, joint moment and AP reaction force were greater in slump than flat and lordotic posture (p< 0.001) but there was no difference between different arm postures. The joint loads (moment and AP reaction force) at the cervico-thoriacic joint were closely related to the head flexion angle (r> 0.86) while those at the lumbosacral joint were correlated to the trunk flexion angle (r> 0.77). In slump posture, the joint moments were close to or over the extreme of the daily life such as sit-to-stand and walking. Consequently, if the slump is continued for a long time, it may cause pain and diseases at the cervico-thoracic and lumbosacral joints.

CONCLUSIONS:

The results of the study indicated that the lordosis or flat would be better spinal postures. Also, keeping arms close to body would be desirable to reduce joint loads.

Effects of the weight configuration of hand load on trunk musculature during static weight holding

The performance of manual material handling tasks is one major cause of lower back injuries. In the current study, we investigated the influence of the weight configuration of hand loads on trunk muscle activities and the associated spinal stability. Thirteen volunteers each performed static weight-holding tasks using two different 9 kg weight bars (with medial and lateral weight configurations) at two levels of height (low and high) and one fixed horizontal distance (which resulted in constant spinal joint moment across conditions). Results of the current study demonstrated that holding the laterally distributed load significantly reduced activation levels of lumbar and abdominal muscles by 9-13% as compared with holding the medially distributed load. We believe such an effect is due to an elevated rotational moment of inertia when the weight of the load is laterally distributed. These findings suggest that during the design and assessment of manual material handling tasks, such as lifting and carrying, the weight configuration of the hand load should be considered. Practitioner summary: Elevated trunk muscle activities were found when holding a medially distributed load vs. a laterally distributed load (with an equivalent external moment to the spine), indicating a reduced spinal stability due to the reduced rotational moment of inertia. The configuration of the hand load should be considered when evaluating manual material handling tasks.

Older females in the workforce - the effects of age on psychophysical estimates of maximum acceptable lifting loads

The number of older workers in the workforce is increasing substantially, and advanced age is associated with factors that could influence musculoskeletal injury risk and work capacity. This study's goals were to test whether psychophysical estimates of maximum acceptable weight of lift (lift_max) differed between younger and older workers, and to examine potential explanatory factors. Twenty-four female workers (half 50 + years; half 20-32 years) self-adjusted a box's mass to their perceived lift_max during four lifting tasks. Older workers' lift_max values were significantly lower (by approximately 24%) than their younger counterparts. There were no age-related differences in resting heart rate, or peak joint angles and final heart rate during the lifting trials. However, the older group demonstrated lower grip strength (by 24%), and lower heart rate reserve during the trials (by 18%). These results question whether current maximum acceptable lifting weights based on psychophysical information are appropriately protective for female workers greater than 50 years of age. Practitioner Summary: This psychophysical study demonstrated that older female workers (aged 50-63 years) selected maximum acceptable lift masses that were (on average) 24% lower than younger workers (aged 20-32 years), which corresponded with lower grip strength and heart rate reserve. Current maximum acceptable lifting weights based on psychophysical information may not protect female workers greater than 50 years of age.

Knowledge, attitudes and beliefs on contributing factors among low back pain patients attending outpatient physiotherapy treatment in Malawi

BACKGROUND

Low back pain (LBP) affects many people globally. Its aetiology is not clear. Patients lack knowledge of its contributing factors and have negative perception about their LBP. This study aimed to identify knowledge, attitudes and beliefs regarding the perceived contributing factors to LBP among patients attending physiotherapy outpatient departments in Malawi. This information can possibly facilitate planning of a LBP education programme in Malawi.

METHODS

A quantitative cross-sectional survey was conducted, using a six-part self-administered questionnaire with questions on demographic information, participants' attitudes and beliefs regarding their LBP, knowledge about the course and causes of LBP, beliefs regarding nine contributing factors to LBP (identified in a Delphi study) and the sources of the participants' knowledge. Data were analysed descriptively using the Statistical Package for Social Sciences (version 19.0). A Chi-square test was used to determine any association between variables (alpha 0.05). All ethical procedures were strictly followed.

RESULTS

Most participants (186, 91.2 %) did not manage to answer all six questions regarding knowledge correctly and were regarded as 'partially knowledgeable' about the course and causes of LBP. More than half (67%) portrayed negative attitudes and beliefs about LBP in general. The findings also showed a statistically significant relationship between knowledge, attitudes and beliefs (p = 0.04).

CONCLUSION

This study highlighted that many patients with LBP in Malawi are not adequately knowledgeable about LBP and hold negative attitudes and beliefs regarding their LBP. Therefore, LBP management programmes in Malawi should include education programmes aimed at empowering patients with knowledge regarding LBP, as well as changing their negative attitudes and beliefs about their pain. Patients' understanding of the cause and nature of their pain may enhance the achievement of treatment goals.

Wearable technology for spine movement assessment: A systematic review

Continuous monitoring of spine movement function could enhance our understanding of low back pain development. Wearable technologies have gained popularity as promising alternative to laboratory systems in allowing ambulatory movement analysis. This paper aims to review the state of art of current use of wearable technology to assess spine kinematics and kinetics. Four electronic databases and reference lists of relevant articles were searched to find studies employing wearable technologies to assess the spine in adults performing dynamic movements. Two reviewers independently identified relevant papers. Customised data extraction and quality appraisal form were developed to extrapolate key details and identify risk of biases of each study. Twenty-two articles were retrieved that met the inclusion criteria: 12 were deemed of medium quality (score 33.4-66.7%), and 10 of high quality (score >66.8%). The majority of articles (19/22) reported validation type studies. Only 6 reported data collection in real-life environments. Multiple sensors type were used: electrogoniometers (3/22), strain gauges based sensors (3/22), textile piezoresistive sensor (1/22) and accelerometers often used with gyroscopes and magnetometers (15/22). Two sensors units were mainly used and placing was commonly reported on the spine lumbar and sacral regions. The sensors were often wired to data transmitter/logger resulting in cumbersome systems. Outcomes were mostly reported relative to the lumbar segment and in the sagittal plane, including angles, range of motion, angular velocity, joint moments and forces. This review demonstrates the applicability of wearable technology to assess the spine, although this technique is still at an early stage of development.

Lumbar muscle structure and function in chronic versus recurrent low back pain: a cross-sectional study

BACKGROUND CONTEXT

Heterogeneity exists within the low back pain (LBP) population. Some patients recover after every pain episode, whereas others suffer daily from LBP complaints. Until now, studies rarely make a distinction between recurrent low back pain (RLBP) and chronic low back pain (CLBP), although both are characterized by a different clinical picture. Clinical experiences also indicate that heterogeneity exists within the CLBP population. Muscle degeneration, like atrophy, fat infiltration, alterations in muscle fiber type, and altered muscle activity, compromises proper biomechanics and motion of the spinal units in LBP patients. The amount of alterations in muscle structure and muscle function of the paraspinal muscles might be related to the recurrence or chronicity of LBP.

PURPOSE

The aim of this experimental study is to evaluate differences in muscle structure (cross-sectional area and lean muscle fat index) and muscle activity of the multifidus (MF) and erector spinae (ES) during trunk extension, in patients with RLBP, non-continuous CLBP, and continuous CLBP.

STUDY DESIGN AND SETTING

This cross-sectional study took place in the university hospital of Ghent, Belgium. Muscle structure characteristics and muscle activity were assessed by magnetic resonance imaging (MRI).

PATIENT SAMPLE

Fifty-five adults with non-specific LBP (24 RLBP in remission, 15 non-continuous CLBP, 16 continuous CLBP) participated in this study.

OUTCOME MEASURES

Total cross-sectional area, muscle cross-sectional area, fat cross-sectional area, lean muscle fat index, T2-rest and T2-shift were assessed.

METHODS

A T1-weighted Dixon MRI scan was used to evaluate spinal muscle cross-sectional area and fat infiltration in the lumbar MF and ES. Muscle functional MRI was used to evaluate the muscle activity of the lumbar MF and ES during a lumbar extension exercise. Before and after the exercise, a pain assessment was performed. This study was supported by grants from the Special Research Fund of Ghent University (DEF12/AOP/022) without potential conflict of interest-associated biases in the text of the paper.

RESULTS

Fat cross-sectional area and lean muscle fat index were significantly higher in MF and ES in continuous CLBP compared with non-continuous CLBP and RLBP (p<.05). No differencesbetween groups were found for total cross-sectional area and muscle cross-sectional area in MF or ES (p>.05). Also, no significant differences between groups for T2-rest were established. T2-shift, however, was significantly lower in MF and ES in RLBP compared with, respectively, non-continuous CLBP and continuous CLBP (p<.05).

CONCLUSIONS

These results indicate a higher amount of fat infiltration in the lumbar muscles, in the absence of clear atrophy, in continuous CLBP compared with RLBP. A lower metabolic activity of the lumbar muscles was seen in RLBP replicating a relative lower intensity in contractions performed by the lumbar muscles in RLBP compared with non-continuous and continuous CLBP. In conclusion, RLBP differs from continuous CLBP for both muscle structure and muscle function, whereas non-continuous CLBP seems comparable with RLBP for lumbar muscle structure and with continuous CLBP for lumbar muscle function. These results underline the differences in muscle structure and muscle function between different LBP populations.

The Composite Strain Index (COSI) and Cumulative Strain Index (CUSI): methodologies for quantifying biomechanical stressors for complex tasks and job rotation using the Revised Strain Index

The Composite Strain Index (COSI) quantifies biomechanical stressors for complex tasks consisting of exertions at different force levels and/or with different exertion times. The Cumulative Strain Index (CUSI) further integrates biomechanical stressors from different tasks to quantify exposure for the entire work shift. The paper provides methodologies to compute COSI and CUSI along with examples. Complex task simulation produced 169,214 distinct tasks. Use of average, time-weighted average (TWA) and peak force and COSI classified 66.9, 28.2, 100 and 38.9% of tasks as hazardous, respectively. For job rotation the simulation produced 10,920 distinct jobs. TWA COSI, peak task COSI and CUSI classified 36.5, 78.1 and 66.6% jobs as hazardous, respectively. The results suggest that the TWA approach systematically underestimates the biomechanical stressors and peak approach overestimates biomechanical stressors, both at the task and job level. It is believed that the COSI and CUSI partially address these underestimations and overestimations of biomechanical stressors. Practitioner Summary: COSI quantifies exposure when applied hand force and/or duration of that force changes during a task cycle. CUSI integrates physical exposures from job rotation. These should be valuable tools for designing and analysing tasks and job rotation to determine risk of musculoskeletal injuries.

An EMG-assisted modeling approach to assess passive lumbar tissue loading in vivo during trunk bending

Lower back pain (LBP) is a condition with high prevalence and high cost both in the United States and around the world. The magnitude of mechanical loading on spine is strongly associated with the occurrence of LBP. Previously, to assess spinal loading, biologically assisted biomechanical models were developed to estimate trunk muscle contraction forces. Loadings on lumbar passive tissues are estimated using anatomical models. However, despite the substantial individual variability in lumbar ligament geometry and viscoelastic properties, the existing anatomical models do not account for these differences. As such, the accuracy of model prediction is compromised especially when mid to full range of trunk motions are involved. This paper describes a new modeling approach to assess lumbar passive tissue loading with the consideration of individual differences in lumbar passive tissue properties. A data set that has trunk bending data from 13 human participants was analyzed; on average, lumbar passive tissue contributes to ∼89% of the total spinal compression force at fully flexed trunk postures; the estimated spinal tissue loadings were in feasible ranges as reported from previous cadaver studies; the estimated spinal loadings were also mostly in agreement with results from previous in vivo studies.

Assisting Frail Seniors With Toileting in a Home Bathroom: Approaches Used by Home Care Providers

Home care providers experience high occupational injury rates. Improving safety is becoming increasingly urgent as this sector expands to support the aging population. Caregivers identify assisting with toileting as a particularly frequent and difficult activity. This mixed-methods observational study identified and analyzed the toileting subactivities that place care providers at the greatest risk of musculoskeletal injury. Eight personal support workers (home care aides) assisted a frail older adult (actor) in a simulated home bathroom. Overall technique and body postures were analyzed. Exposure to musculoskeletal injury risk factors (low back loads and time in extreme trunk postures) was greatest when removing/replacing clothing and providing posterior perineal care; high loads were also possible during transfers. Exposures can be reduced by lowering the pants only to knee level or squatting to raise them. A bidet seat or attachment can perform perineal cleaning, which accounted for 32% of time in severe trunk flexion.

Work Characteristics Associated with Physical Functioning in Women

Women make up almost half of the labor force with older women becoming a growing segment of the population. Work characteristics influence physical functioning and women are at particular risk for physical limitations. However, little research has explored the effects of work characteristics on women’s physical functioning. U.S. women between the ages of 50 and 79 were enrolled in the Women’s Health Initiative Observational Study between 1993 and 1998. Women provided job titles and years worked at their three longest-held jobs (n = 79,147). Jobs were linked to characteristics in the Occupational Information Network. Three categories of job characteristics related to substantive complexity, physical demand, and social collaboration emerged. The association between job characteristics and physical limitations in later life, measured using a SF-36 Physical Functioning score <25th percentile, was examined using modified Poisson regression. After controlling for confounding variables, high physical demand was positively associated with physical limitations (RR = 1.09 CI: 1.06–1.12) and substantively complex work was negatively associated (RR = 0.94, CI: 0.91–0.96). Jobs requiring complex problem solving, active learning, and critical thinking were associated with better physical functioning. Employers should explore opportunities to reduce strain from physically demanding jobs and incorporate substantively complex tasks into women’s work to improve long-term health.

Do Personal Factors or Types of Physical Tasks Predict Workplace Injury?

Occupational health research has shown that certain worker and job characteristics are risk factors for workplace injuries. Workers who engage in physically demanding jobs, especially those jobs that involve repetitive motion, are at greater risk for work-related musculoskeletal disorders (WMSD). These risks are particularly prevalent in the health care sector. It is often reported that nurses are at higher risk of workplace musculoskeletal injury than other health care workers due to frequent lifting and transfer of patients and the prevalence of workplace violence. However, many analyses of the physical requirements of jobs do not consider the modifying effect of time spent on a physical task and the risk of WMSD. This study compared the risks of WMSD among workers in health care facilities based on the type of physical tasks and amount of time workers spent on such tasks. Workers who worked longer on a physical task reported more WMSD than those who spent less time on the same physical task. The risk of WMSD was twice as high (odds ratio [OR] = 2.3) among workers who sit less than 2 hours each day compared with those who sit longer. This study found that physical tasks associated with health care jobs and the amount of time spent on these tasks constitutes serious risk factors for WMSD.

Pathways between under/unemployment and health among racialized immigrant women in Toronto

OBJECTIVE

We sought to document pathways between under/unemployment and health among racialized immigrant women in Toronto while exploring the ways in which gender, class, migration and racialization, as interlocking systems of social relations, structure these relationships.

DESIGN

We conducted 30 interviews with racialized immigrant women who were struggling to get stable employment that matched their education and/or experience. Participants were recruited through flyers, partner agencies and peer researcher networks. Most interviews (21) were conducted in a language other than English. Interviews were transcribed, translated as appropriate and analyzed using NVivo software. The project followed a community-based participatory action research model.

RESULTS

Under/unemployment negatively impacted the physical and mental health of participants and their families. It did so directly, for example through social isolation, as well as indirectly through representation in poor quality jobs. Under/unemployment additionally led to the intensification of job search strategies and of the household/caregiving workload which also negatively impacted health. Health problems, in turn, contributed to pushing participants into long-term substandard employment trajectories. Participants' experiences were heavily structured by their social location as low income racialized immigrant women.

CONCLUSIONS

Our study provides needed qualitative evidence on the gendered and racialized dimensions of under/unemployment, and adverse health impacts resulting from this. Drawing on intersectional analysis, we unpack the role that social location plays in creating highly uneven patterns of under/unemployment and negative health pathways for racialized immigrant women. We discuss equity informed strategies to help racialized immigrant women overcome barriers to stable work that match their education and/or experience.

Hip and knee net joint moments that correlate with success in lateral load transfers over a low friction surface

We previously described two different preferred strategies used to perform a lateral load transfer. The wide stance strategy was not used successfully on a low-friction surface, while the narrow stance strategy was successful. Here, we retrospectively examined lower extremity net joint moments between successful and unsuccessful strategies to determine if there is a kinetic benefit consideration that may go into choosing the preferred strategy. Success vs. failure over a novel slippery surface was used to dichotomise 35 healthy working-age individuals into the two groups (successful and unsuccessful). Participants performed lateral load transfers over three sequential surface conditions: high friction, novel low friction and practised low friction. The unsuccessful strategy required larger start torques, but lower dynamic moments during transfer compared to the successful strategy. These results indicate that the periodically unsuccessful strategy may be preferred because it requires less muscle recruitment and lower stresses on lower extremity soft tissues. Practitioner Summary: The reason for this paper is to retrospectively examine the joint moment in two different load transfer strategies that are used in a lateral load transfer. We found that periodically unsuccessful strategies that we previously reported may be a beneficial toward reduced lower extremity joint stresses.

Loading of the lumbar spine during backpack carriage

Backpack carriage is significantly associated with a higher prevalence of low back pain. Elevated compression and shear forces in the lumbar intervertebral discs are known risk factors. A novel method of calculating the loads in the lumbar spine during backpack carriage is presented by combining physical and numerical modelling. The results revealed that to predict realistic lumbar compression forces, subject-specific lumbar curvature data were not necessary for loads up to 40 kg. In contrast, regarding shear forces, using subject-specific lumbar curvature data from upright MRI measurements as input for the rigid body model significantly altered lumbar joint force estimates.

The Impact of an Ergonomics Intervention on Psychosocial Factors and Musculoskeletal Symptoms among Thai Hospital Orderlies

(1) Background: Musculoskeletal disorders have a multifactorial etiology that is not only associated with physical risk factors, but also psychosocial risk factors; (2) Objective: This study evaluated the effects of an ergonomic intervention on musculoskeletal disorders and psychosocial risk factors; (3) Material and Methods: This study took a participatory ergonomic (PE) approach with a randomized controlled trial (RCT) conducted at tertiary care hospitals during July to December 2014. A group of hospital orderlies in Thailand were randomly selected for examination. Fifty orderlies were placed in a case group and another 50 orderlies were placed in the control group. The Nordic Musculoskeletal Disorders Questionnaire (NMQ) and the Copenhagen Psychosocial Questionnaire (COPSOQ) were used for data collection before and after the intervention program; (4) Results: The most commonly reported problem among hospital orderlies was found to be lower back symptoms (82%). The study found significant differences in prevalence rates of reported musculoskeletal conditions in the arm, upper back, and lower back regions before and after intervention. Findings showed that psychosocial risk factors were affected by the intervention. COPSOQ psychosocial risk factors were significantly different pre/post intervention. These variables included: work pace, influence at work, meaning of work, predictability, rewards, role conflicts, and social support from supervisors. No other psychosocial risk factors were found to be significant; (5) Conclusions: Positive results were observed following the intervention in the work environment, particularly in terms of reducing physical work environment risk factors for musculoskeletal disorders and increasing promotion factors of the psychosocial work environment.

Differences in lumbopelvic rhythm between trunk flexion and extension

BACKGROUND

Trunk flexion and extension have already been found to have different characteristics, such as those in lumbopelvic rhythm. Although a more advanced method of quantifying such rhythm, lumbopelvic continuous relative phase and phase variability have not been used to explore the differences between trunk flexion and extension motions. This information is important since abnormal lumbopelvic coordination patterns increase the risk of low back pain. The current study investigated the differences in lumbopelvic rhythm between trunk flexion and extension, and how the rhythm changed within each of the two motions.

METHODS

Thirteen subjects performed pace-controlled trunk flexion/extension motions in the sagittal plane while lumbar and pelvis kinematics data were recorded, such that the lumbopelvic continuous relative phase and phase variability could be calculated to quantify lumbopelvic rhythm.

FINDINGS

Trunk extension motion had significantly smaller lumbopelvic continuous relative phase and phase variability than flexion motion, which indicated a more in-phase and stable rhythm. Additionally, the lumbopelvic rhythm within trunk extension motion changed from a more in-phase and stable pattern to a more out-of-phase and unstable pattern; by contrast, the opposite change (from out-of-phase and unstable to in-phase and stable) was observed in trunk flexion.

INTERPRETATION

Findings of the current study provided important information about the differences in lumbopelvic rhythm between trunk flexion and extension motions. Quantifying these patterns provides the means for identifying abnormal patterns in a clinical setting, and could serve as normative benchmarks during low back pain rehabilitation plans.

What Challenges Manual Workers' Ability to Cope with Back Pain at Work, and What Influences Their Decision to Call in Sick?

INTRODUCTION

Although back pain (BP) is a very common cause for sickness absence, most people stay at work during BP episodes. Existing knowledge on the factors influencing the decision to stay at work despite pain is limited. The aim of this study was to explore challenges for coping with BP at work and decisive factors for work attendance among workers with high physical work demands.

METHODS

Three focus groups (n = 20) were conducted using an explorative inductive method. Participants were public-employed manual workers with high physical work demands. All had personal BP experience. Thematic analysis was used for interpretation. Results were matched with the Flags system framework to guide future recommendations.

RESULTS

Workers with BP were challenged by poor physical work conditions and a lack of supervisor support/trust (i.e. lack of adjustment latitude). Organization of workers into teams created close co-worker relationships, which positively affected BP coping. Workers responded to BP by applying helpful individual adjustments to reduce or prevent pain. Traditional ergonomics was considered inconvenient, but nonetheless ideal. When pain was not decisive, the decision to call in sick was mainly governed by workplace factors (i.e. sick absence policies, job strain, and close co-workers relationships) and to a less degree by personal factors.

CONCLUSION

Factors influencing BP coping at work and the decision to report sick was mainly governed by factors concerning general working conditions. Creating a flexible and inclusive working environment guided by the senior management and overall work environment regulations seems favourable.

Epidemiology of low back pain in adults

OBJECTIVE

Low back pain affects many individuals. It has profound effects on well-being and is often the cause of significant physical and psychological health impairments. Low back pain also affects work performance and social responsibilities, such as family life, and is increasingly a major factor in escalating health-care costs. A global review of the prevalence of low back pain in the adult general population has shown its point prevalence to be approximately 12%, with a one-month prevalence of 23%, a one-year prevalence of 38%, and a lifetime prevalence of approximately 40%. Furthermore, as the population ages over the coming decades, the number of individuals with low back pain is likely to increase substantially. This comprehensive review is undertaken to assess the increasing prevalence of low back pain and the influence of comorbid factors, along with escalating costs.

MATERIALS AND METHODS

A narrative review with literature assessment.

RESULTS

In the USA, low back pain and related costs are escalating. Based on the available literature, it appears that the prevalence of low back pain continues to increase, along with numerous modalities and their application in managing low back pain. Comorbid factors with psychological disorders and multiple medical problems, including obesity, smoking, lack of exercise, increasing age, and lifestyle factors, are considered as risk factors for low back pain.

CONCLUSION

Although it has been alleged that low back pain resolves in approximately 80% to 90% of patients in about six weeks, irrespective of the administration or type of treatment, with only 5% to 10% of patients developing persistent back pain, this concept has been frequently questioned as the condition tends to relapse and most patients experience multiple episodes years after the initial attack.

Psychosocial Work Environment and Musculoskeletal Symptoms among 21-Year-Old Workers: A Population-Based Investigation (2011-2013)

Background

The current labour market is becoming more flexible and informal, with job insecurity selectively affecting young workers. However, the role of these increasing adverse psychosocial working conditions on health outcomes remains little known among newly employed workers.

Objective

To estimate the associations between psychosocial work environment and musculoskeletal outcomes (widespread pain syndrome features and regional pain) in a population-based sample of young workers.

Methods

Cross-sectional data from workers aged 21 years were collected during the third wave of the EPITeen cohort study (2011-2013; n=650). The Job Content Questionnaire was used to characterize the psychosocial work environment according to the demand-control-support model. Data on pain and non-pain dimensions of the widespread pain syndrome (Fibromyalgia Survey Questionnaire) as well as on regional musculoskeletal pain (Nordic Musculoskeletal Questionnaire) were also collected. Crude and adjusted odds ratios (OR) with 95% confidence intervals (95% CI) were computed using logistic regression and all estimates were adjusted for sex, education and occupational biomechanical demands.

Results

Job insecurity was significantly associated to the non-pain dimension of the widespread pain syndrome (adjusted OR [95% CI]=1.51 [1.08, 2.12]). Young workers with strain jobs were significantly more likely to report high levels of non-pain symptoms when compared with those with no-strain jobs and this effect was even stronger when social support was added to the main exposure: workers with strain jobs and low social support had twice the odds of reporting high levels of non-pain features than those with high strain but high social support jobs (adjusted OR=1.86, 95% CI: 1.04, 3.31). These significant associations were not observed when widespread pain or multisite regional pain were the outcomes.

Conclusion

In the beginning of professional life, high strain jobs were associated to non-pain complaints, especially when the work environment provided also low social support.

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.