Lower back problems and occupational risk factors in a South African steel industry

Traditional versus dynamic sitting: Lumbar spine kinematics and pain during computer work and activity guided tasks

Dynamic sitting may mitigate low back pain during prolonged seated work. The current study compared pelvis and lumbar spine kinematics, pain, and work productivity, in traditional and dynamic sitting. Sixteen participants completed three 20-min blocks of computer work and activity guided tasks in a traditional office chair or backless and multiaxial rotating seat pan while kinematics were measured from accelerometers on the low back. Pain ratings were recorded on a visual analogue scale every 10 min. Similar pelvis and lumbar kinematics emerged when performing computer work in traditional and dynamic sitting. Pelvis and lumbar sagittal and frontal plane shifts and fidgets were largest for dynamic sitting in the activity guided tasks. Buttocks pain was higher in dynamic sitting, but low back pain and work productivity were unaffected. Dynamic sitting increased spine movement during activity guided tasks, without negatively impacting lumbar kinematics, low back pain, or productivity during seated computer work.

Challenges of Measuring Self-Reported Exposure to Occupational Biomechanical Risk Factors Amongst People with Low Literacy Engaged in Manual Labour: Findings from a Cross-Cultural Adaptation and Psychometric Investigation in an African Population with Chronic Low Back Pain

PURPOSE

Occupational biomechanical factors are implicated in the aetiology and progression of low back pain (LBP). This study cross-culturally adapted and psychometrically investigated the Occupational Risk Factor Questionnaire (ORFQ) in a low literate Nigerian Igbo population with chronic LBP.

METHODS

Forward and back translation of the original ORFQ by clinical and non-clinical translators was followed by an expert committee review. The adapted ORFQ was pre-tested amongst rural Nigerian adults with chronic LBP using cognitive think-aloud interviewing. Internal consistency (Cronbach's alpha) and test-retest reliability (unweighted and linear weighted k statistic for item-by-item agreement, and intra-class correlation coefficient-ICC) were investigated amongst 50 rural and urban Nigerian dwellers with chronic LBP. Spearman's correlation and regression analyses were conducted with the Igbo-ORFQ, and measures of disability [World Health Organisation Disability Assessment Schedule (WHODAS 2.0), Roland Morris Disability Questionnaire (RMDQ), Back performance scale (BPS)], pain intensity [Eleven-point box scale (BS-11)] and social support [Multidimensional Scale of Perceived Social Support (MSPSS)], to test construct validity with 200 rural Nigerian dwellers with chronic LBP.

RESULTS

Cross-cultural adaptation highlighted difficulty conceptualising and concretising exposure to biomechanical risk factors. Item-by-item agreement, internal consistency (α = 0.84) and intraclass correlation coefficient (ICC = 0.83) were good. Some unexpected direction of associations between the biomechanical components of the Igbo-ORFQ, and disability, pain intensity, and social support prohibits establishment of construct validity.

CONCLUSION

Prospective studies comparing the Igbo-ORFQ to other measures of exposure to occupational biomechanical risk factors are required to establish the construct validity of the Igbo-ORFQ.

Biomechanical analysis of lifting on stable versus unstable surfaces-a laboratory-based proof-of-concept study

Background

Many workers performing manual handling tasks suffer from musculoskeletal disorders (MSD). Previous research has identified several loading aspects associated with manual handling, but it is still unknown if lifting on an unstable surface is associated with increased biomechanical loading of different body parts.

Aim

This proof-of-concept study aims to study what kinematic and kinetic movement parameters, such as movement time, joint angles, torque, and muscle activity are feasible and of importance when studying the effect of lifting on surfaces with varying degrees of stability in an experimental set-up.

Methods

Measurements were taken during three different surface conditions: stable, slightly unstable, and unstable. The participants were instructed to lift a box from the floor and place it on a table in front of them. The weight of the box varied from 0.5 to 15.5 kg. By using a motion capture system (VICON) with 28 reflective markers placed on the participants and one on the box, one Kistler force plate for measuring force levels and center of pressure movements (CoP), and four electromyographic transmitters (EMG), we analyzed the downward and upward phases of the lifting movement, using the Friedman’s test for repeated measures.

Results

Statistically significant results with less joint movements in the lower and upper back were seen with increased instability during both the downward and upward phases. The decrease in trunk movements with increased instability resulted in a somewhat more flexed knee position during the movement, a lower torque in the lower back, and a decrease in CoP movements, but no differences in movement time or muscle activity in back and knee muscles.

Conclusion

Lifting while standing on unstable surfaces resulted in an alteration of both kinematics and kinetics parameters; however, further studies regarding whether this is an additional risk factor for developing lower back pain are needed. Muscle activity levels were not altered due to instability and due to the complexity of the measurement, and we suggest not including EMG measures in future experiments of this type.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40814-022-01157-2.

Musculoskeletal pain and sedentary behaviour in occupational and non-occupational settings: a systematic review with meta-analysis

BACKGROUND

Sedentary behaviour (SB; time spent sitting) is associated with musculoskeletal pain (MSP) conditions; however, no prior systematic review has examined these associations according to SB domains. We synthesised evidence on occupational and non-occupational SB and MSP conditions.

METHODS

Guided by a PRISMA protocol, eight databases (MEDLINE, CINAHL, PsycINFO, Web of Science, Scopus, Cochrane Library, SPORTDiscus, and AMED) and three grey literature sources (Google Scholar, WorldChat, and Trove) were searched (January 1, 2000, to March 17, 2021) for original quantitative studies of adults ≥ 18 years. Clinical-condition studies were excluded. Studies' risk of bias was assessed using the QualSyst checklist. For meta-analyses, random effect inverse-variance pooled effect size was estimated; otherwise, best-evidence synthesis was used for narrative review.

RESULTS

Of 178 potentially-eligible studies, 79 were included [24 general population; 55 occupational (incuding15 experimental/intervention)]; 56 studies were of high quality, with scores > 0.75. Data for 26 were meta-synthesised. For cross-sectional studies of non-occupational SB, meta-analysis showed full-day SB to be associated with low back pain [LBP - OR = 1.19(1.03 - 1.38)]. Narrative synthesis found full-day SB associations with knee pain, arthritis, and general MSP, but the evidence was insufficient on associations with neck/shoulder pain, hip pain, and upper extremities pain. Evidence of prospective associations of full-day SB with MSP conditions was insufficient. Also, there was insufficient evidence on both cross-sectional and prospective associations between leisure-time SB and MSP conditions. For occupational SB, cross-sectional studies meta-analysed indicated associations of self-reported workplace sitting with LBP [OR = 1.47(1.12 - 1.92)] and neck/shoulder pain [OR = 1.73(1.46 - 2.03)], but not with extremities pain [OR = 1.17(0.65 - 2.11)]. Best-evidence synthesis identified inconsistent findings on cross-sectional association and a probable negative prospective association of device-measured workplace sitting with LBP-intensity in tradespeople. There was cross-sectional evidence on the association of computer time with neck/shoulder pain, but insufficient evidence for LBP and general MSP. Experimental/intervention evidence indicated reduced LBP, neck/shoulder pain, and general MSP with reducing workplace sitting.

CONCLUSIONS

We found cross-sectional associations of occupational and non-occupational SB with MSP conditions, with occupational SB associations being occupation dependent, however, reverse causality bias cannot be ruled out. While prospective evidence was inconclusive, reducing workplace sitting was associated with reduced MSP conditions. Future studies should emphasise prospective analyses and examining potential interactions with chronic diseases.

PROTOCOL REGISTRATION

PROSPERO ID # CRD42020166412 (Amended to limit the scope).

The Prevalence of Musculoskeletal Disorders among Miners around the World: A Systematic Review and Meta-Analysis

Background

Musculoskeletal disorders are responsible for significant problem for workers' health. The present study aimed to investigate the prevalence of musculoskeletal disorders among mining workers.

Methods

This systematic review and meta-analysis study were designed in 2020 (from Jan to Mar). The researchers searched five international databases Medline/PubMed, ProQuest, Scopus, Embase and Web of Science. All analyzes were performed using STATA statistical software.

Results

The search results were 447 articles and after screening stage finally 50 studies were included in review. The highest number of studies (26 studies) reported the prevalence of musculoskeletal disorders of upper back and 4 studies reported the prevalence of musculoskeletal disorders of the arms and ankles & feet. The results of meta-analysis based on prevalence in different organs showed that the highest prevalence of musculoskeletal disorders was in the upper back and the lowest in the knees with a prevalence of 50.39% (CI 95%: 31.23-54.73%) and 16.03% (CI 95%: 11.78-20.28%), respectively.

Conclusion

The prevalence of musculoskeletal disorders among miners is relatively high. Therefore, supervisors and mine managers should pay more attention to reducing musculoskeletal disorders and increasing the ergonomic level of mines in order to increase workers' health.

Measuring Effects of Two-Handed Side and Anterior Load Carriage on Thoracic-Pelvic Coordination Using Wearable Gyroscopes

Manual carrying of heavy weight poses a major risk for work-related low back injury. Body-worn inertial sensors present opportunities to study the effects of ambulatory work tasks such as load carriage in more realistic conditions. An immediate effect of load carriage is reflected in altered gait kinematics. To determine the effects of load carriage mode and magnitude on gait parameters using body-worn angular rate gyroscopes, two laboratory experiments (n = 9 and n = 10, respectively) were conducted. Participants performed walk trials at self-selected speeds while carrying hand loads in two modes (two-handed side vs. anterior) at four load levels (empty-handed, 4.5 kg, 9.1 kg, and 13.6 kg). Six measures of postural sway and three measures of thoracic-pelvic coordination were calculated from data recorded by four body-worn gyroscopes for 1517 gait cycles. Results demonstrated that, after adjusting for relative walking speed, thoracic-pelvic sway, and movement coordination particularly in the coronal and transverse planes, characterized by gyroscope-based kinematic gait parameters, are systematically altered by the mode of load carriage and load magnitude. Similar trends were obtained for an anthropometrically homogenous (Expt-1) and diverse (Expt-2) sample after adjusting for individual differences in relative walking speed. Measures of thoracic-pelvic coordination and sway showed trends of significant practical relevance and may provide sufficient information to typify alterations in gait across two-handed side vs. anterior load carriage of different load magnitudes. This study contributes to understanding the effects of manual load carriage on thoracic-pelvic movement and the potential application of body-worn gyroscopes to measuring these gait adaptations in naturalistic work settings.

The Impact of Heavy Load Carrying on Musculoskeletal Pain and Disability Among Women in Shinyanga Region, Tanzania

Background

Heavy load carrying has been associated with musculoskeletal discomfort (MSD) and disability. However, there is a lack of research investigating this association in resource-constrained settings where heavy load carrying by women is common.

Objectives

We assessed the impact of heavy load carrying on musculoskeletal pain and disability among women in Shinyanga Region, Tanzania, in an exploratory cross-sectional study.

Methods

Eligible participants were a convenience sample of women, at least 18 years of age, who passed a study recruitment site carrying a load. We collected information on load-carrying practices, including frequency and time spent carrying water, wood, agricultural products, coal, sand, or rocks, and measured the weight of the load carried at the time. Outcomes included self-reported MSDs, defined as experiencing pain lasting >3 days in the neck, head, back, knees, feet and/or ankles within the last 1 year, and related disability. Using multivariable logistic regression we assessed for associations between load carrying exposures and MSDs and disability.

Findings

Results showed a high prevalence of MSDs across the body regions assessed and evidence to suggest a relationship of back pain and related disability with several measures of load-carrying, including duration, frequency, and weight. Multivariable analyses revealed associations of increased load carrying exposures with low back pain (LBP) and related disability, including statistically significant increases in odds of LBP with increasing weight, total duration of load carrying/week and cumulative loads/week.

Conclusions

Findings indicate a substantial burden of MSDs and disability in this population of women who carry heavy loads daily. The extent of discomfort and disability increased with increasing exposure to various load-carrying measures, especially for LBP. Larger epidemiologic studies that definitively assess relationships of load carrying with MSDs and disability are warranted.

Development and Investigation of a Wearable Aid for a Load Carriage Task

Anterior load carriage tasks are common and can lead to musculoskeletal disorders such as lower back pain. The objectives of this study were to develop a wearable carriage aid and examine its effectiveness on physical demands while considering the potential moderating influence of the carried load. The study consisted of two within-subject factors: device and load. For the former, two levels were tested: with and without the device worn. For the latter, two loads were examined: 15 and 30% of each individual’s body mass. Sixteen participants walked on a treadmill for five minutes at a constant speed for each condition. Physical demands were quantified using objective (EMG-based) and subjective (discomfort) measures. Wearing the device reduced static and median anterior deltoid, trapezius, and biceps brachii muscle activations. Increasing the carried load increased most physical demand measures. Two significant Device×Load interactions were observed; for the anterior deltoid and trapezius median activation measures, the influence of increasing load was lower when the device was worn. While slightly increasing perceived discomfort in the lower back, wearing the device reduced shoulder, neck, and hand/wrist discomfort. While the study demonstrated a potential for the device, future work is required under more realistic and diverse testing conditions.

Ergonomic Principles as an Adjunct to the Profession of Biokinetics

Work-related injuries date back to antiquity. Attempts to resolve these work-related challenges have, inter alia, led to the establishment of the professions of Ergonomics, Occupational Therapy, Physiotherapy, Occupational Hygiene, and Biokinetics. The objective of this article is to illustrate the value of Ergonomic principles as an adjunct to the profession of Biokinetics. Insofar as Ergonomics addresses the physical and environmental risks which predispose and precipitate injuries, the profession of Ergonomics is primarily concerned with the practice of eradicating work-related challenges that impede human-machine interfacing, and which adversely influence work productivity and employee health. While Occupational Therapy and Biokinetics, by rehabilitating work-related injuries, assist in improving working conditions, little is known about the exact interface between the professions of Ergonomics and Biokinetics. The Google Scholar database was consulted in order to determine the relationship between Ergonomics and Biokinetics. The key words used were ergonomics and biokinetics and lead to the identification of 545 records, none of which pertained to the aforementioned subject. A subsequent search was conducted using the key words work-related musculoskeletal injuries and biokinetics. This search identified 925 records, the number of which were reduced to 42 (4.76%) after the exclusion of patents (n = 24), citations (n = 3), and nonbiokinetic work-related injury research (n = 856). Given that many work-related injuries are managed through the use of biokinetic rehabilitation, knowledge of the physical ergonomic risk factors at play will afford biokineticists an enhanced understanding of the etiology of work-related injuries, thereby helping to improve the vigor of the rehabilitation.

An update on the prevalence of low back pain in Africa: a systematic review and meta-analyses

BACKGROUND

Low back pain (LBP) remains a common health problem and one of the most prevalent musculoskeletal conditions found among developed and developing nations. The following paper reports on an updated search of the current literature into the prevalence of LBP among African nations and highlights the specific challenges faced in retrieving epidemiological information in Africa.

METHODS

A comprehensive search of all accessible bibliographic databases was conducted. Population-based studies into the prevalence of LBP among children/adolescents and adults living in Africa were included. Methodological quality of included studies was appraised using an adapted tool. Meta-analyses, subgroup analyses, sensitivity analyses and publication bias were also conducted.

RESULTS

Sixty-five studies were included in this review. The majority of the studies were conducted in Nigeria (n = 31;47%) and South Africa (n = 16;25%). Forty-three included studies (66.2%) were found to be of higher methodological quality. The pooled lifetime, annual and point prevalence of LBP in Africa was 47% (95% CI 37;58); 57% (95% CI 51;63) and 39% (95% CI 30;47), respectively.

CONCLUSION

This review found that the lifetime, annual and point prevalence of LBP among African nations was considerably higher than or comparable to global LBP prevalence estimates reported. Due to the poor methodological quality found among many of the included studies, the over-representation of affluent countries and the difficulty in sourcing and retrieving potential African studies, it is recommended that future African LBP researchers conduct methodologically robust studies and report their findings in accessible resources.

TRIAL REGISTRATION

The original protocol of this systematic review was initially registered on PROSPERO with registration number CRD42014010417 on 09 July 2014.

Changes in Lumbopelvic Movement and Muscle Recruitment Associated with Prolonged Deep Squatting: A Pilot Study

This study examined the changes in spinal kinematics and muscle recruitment of the lumbopelvic region associated with prolonged squatting. Eight subjects with chronic nonspecific low back pain (LBP) and eight asymptomatic subjects (AS) performed squat-to-stand and reverse movements, before and immediately after 15 min deep-squatting. Within-group and between-group differences in lumbopelvic kinematics and electromyographic activity acquired in lumbar erector spinae (ES), gluteus maximus (GM), and vastus lateralis (VL) were analyzed. During squat-to-stand after squatting, the LBP group showed slower then faster lumbar movement in the second and third quartiles, respectively. In the second quartile, the AS group moved with a significantly greater lumbar angle. However, significantly greater bilateral GM activity (+4–4.5%) was found in the LBP group only. A more profound decrease in bilateral ES activity (−10%) was also shown in the LBP group, yet this was nonsignificant compared to the AS group (−4%). In the third quartile, only the LBP group moved with a significantly greater lumbar angle, together with a significant increase in bilateral ES (+6–8%) and GM muscle (+2–3%) activity. The findings of the altered pattern of joint kinematics and recruitment of the key lumbopelvic muscles displayed in the LBP group inform on the possible mechanisms that may contribute to the increased risk of developing lumbar dysfunctions for people who work in prolonged squatting postures.

Influence of anterior load carriage on lumbar muscle activation while walking in stable and unstable shoes

Load carriage can be harmful for workers, and alternative interventions to reduce back pain while walking and carrying loads are necessary. Unstable shoes have been used to improve balance and reduce back pain, but it is unknown whether walking wearing unstable shoes while carrying loads anteriorly causes excessive trunk extensors muscle activation. The aim of this study was to investigate the effects of different shoe types and anterior load carriage on gait kinematics and lumbar electromyographic (EMG) activity. Fourteen adults that predominantly walk or stand during the work day were asked to walk with and without carrying 10% of body mass anteriorly while wearing regular walking shoes (REG) and unstable shoes (MBT). The effects of shoe type, load carriage, and shoe × load interactions on the longissimus thoracis (LT) and iliocostalis lumborum (IC) EMG, stride duration, and stride frequency were assessed. MBT shoes induced a significant increase in LT (44.4 ± 35%) and IC EMG (33.0 ± 32%, p < .005), while load carriage increased LT (58.5 ± 41%) and IC EMG (55.1 ± 32%, p < .001). No significant shoe × load interaction was found (p>.05). However, walking wearing MBT shoes while carrying loads induced a 46 ± 40% higher EMG activity compared to walking wearing MBT shoes without load carriage. No effects of shoes or load carriage were found on stride duration and stride frequency. It was concluded that walking wearing MBT shoes and carrying 10% of total body mass induced greater activation of trunk extensors muscle compared to these factors in isolation, such a combination may not influence gait patterns.

Simulating ideal assistive devices to reduce the metabolic cost of walking with heavy loads

Wearable robotic devices can restore and enhance mobility. There is growing interest in designing devices that reduce the metabolic cost of walking; however, designers lack guidelines for which joints to assist and when to provide the assistance. To help address this problem, we used musculoskeletal simulation to predict how hypothetical devices affect muscle activity and metabolic cost when walking with heavy loads. We explored 7 massless devices, each providing unrestricted torque at one degree of freedom in one direction (hip abduction, hip flexion, hip extension, knee flexion, knee extension, ankle plantarflexion, or ankle dorsiflexion). We used the Computed Muscle Control algorithm in OpenSim to find device torque profiles that minimized the sum of squared muscle activations while tracking measured kinematics of loaded walking without assistance. We then examined the metabolic savings provided by each device, the corresponding device torque profiles, and the resulting changes in muscle activity. We found that the hip flexion, knee flexion, and hip abduction devices provided greater metabolic savings than the ankle plantarflexion device. The hip abduction device had the greatest ratio of metabolic savings to peak instantaneous positive device power, suggesting that frontal-plane hip assistance may be an efficient way to reduce metabolic cost. Overall, the device torque profiles generally differed from the corresponding net joint moment generated by muscles without assistance, and occasionally exceeded the net joint moment to reduce muscle activity at other degrees of freedom. Many devices affected the activity of muscles elsewhere in the limb; for example, the hip flexion device affected muscles that span the ankle joint. Our results may help experimentalists decide which joint motions to target when building devices and can provide intuition for how devices may interact with the musculoskeletal system. The simulations are freely available online, allowing others to reproduce and extend our work.

Modelling the spine as a deformable body: Feasibility of reconstruction using an optoelectronic system

The aims of this study were to develop a kinematic model of the spine, seen as a continuous deformable body and to identify the smallest set of surface markers allowing adequate measurements of spine motion. The spine is widely considered as a rigid body or as a kinematic chain made up of a smaller number of segments, thereby introducing an approximation. It would be useful to have at our disposal a technique ensuring accurate and repeatable measurement of the shape of the whole spine. Ten healthy subjects underwent a whole-spine radiographic assessment and, simultaneously, an optoelectronic recording. Polynomial interpolations of the vertebral centroids, of the whole set of markers were performed. The similarity of the resulting curves was assessed. Our findings indicate that spine shape can be reproduced by 5th order polynomial interpolation. The best approximating curves are obtained from either 10- or 9-marker sets. Sagittal angles are systematically underestimated.

Effect of a specific exercise program on the strength and resistance levels of lumbar muscles in warehouse workers

OBJECTIVE

The aim of this study was to verify the influence of a specific exercise program on the strength and resistance levels of lumbar flexors and extensors in warehouse workers.

MATERIALS AND METHODS

The population used in this randomized controlled trial included 557 warehouse male workers from a food distribution company in Oporto/Portugal. Upon the application of the selection criteria, 98 workers deemed eligible were randomized in two groups: 57 were assigned to the intervention group and 41 to the control group. The intervention included 9 easily-executed exercises to promote stretching and strengthening of the lumbar region, to be executed daily, at the beginning of the working time, at the company facilities and lasting 8'. Trunk muscles' voluntary strength and resistance were measured using an isometric electronic dynamometer (Globus Ergometer, Globus, Codigné, Italy) at baseline and eleven months after implementing the exercise program. The data was analyzed using SPSS®, version 17.0.

RESULTS

After implementation of the exercise program, in the intervention group, all variables increased, significant differences were observed as for the muscle strength and resistance values (p = 0.014 and p = 0.006, respectively), as well as in the ratio extensors/flexors (p = 0.037). In the control group, all variables decreased, with a statistically significant decrease of the trunk flexors strength level (p = 0.009).

CONCLUSION

The results of this study suggest that a specific exercise intervention program can increase trunk extensors strength and resistance.

Causal assessment of workplace manual handling or assisting patients and low back pain: results of a systematic review

BACKGROUND CONTEXT

Low back pain (LBP) is a common musculoskeletal disorder associated with a considerable social and economic burden within the working-age population. Despite an unclear etiology, numerous physical activities are suspected of leading to LBP. Declaring a causal relationship between occupational activities and LBP remains challenging and requires a methodologically rigorous approach.

PURPOSE

To conduct a systematic review focused on assessing the potentially causal relationship between workplace manual handling or assisting patients and LBP.

STUDY DESIGN

Systematic review of the literature.

SAMPLES

Studies reporting an association between workplace manual handling or assisting patients and LBP.

OUTCOME MEASURES

Numerical association between different levels of exposure to manual handling or assisting patients, and the presence or severity of LBP.

METHODS

A systematic review was conducted 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 content experts. The methodological quality of each study was assessed using a modified Newcastle-Ottawa Scale (NOS) for observational studies. The overall level of evidence supporting various Bradford-Hill criteria for causality for each category of manual handling or assisting patients and type of LBP was then evaluated. Studies were deemed of higher quality if they received a score of five or more on the modified NOS and used appropriate statistical analysis methods.

RESULTS

This search yielded 2,766 citations, and 32 studies met the eligibility criteria. Three high-quality studies reported on manual handling and LBP, including two prospective cohorts and one cross-sectional design. None demonstrated a significant association in most of their multivariate risk estimates. One study was able to assess dose-response and temporality, but its results did not support these criteria. Only one study discussed the biological plausibility of this association. Four high-quality studies evaluated assisting patients and LBP, including two case-controls, one cross-sectional, and one prospective cohort design. These studies were consistent in reporting no significant association. Two studies demonstrated a nonsignificant dose-response trend, and two studies discussed the biological plausibility of this association. No studies were able to demonstrate the temporality or experiment criteria.

CONCLUSIONS

The studies reviewed did not support a causal association between workplace manual handling or assisting patients and LBP in a Bradford-Hill framework. Conflicting evidence in specific subcategories of assisting patients was identified, suggesting that tasks such as assisting patients with ambulation may possibly contribute to LBP. It appears unlikely that workplace manual handling or assisting patients is independently causative of LBP in the populations of workers studied.

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 lifting and low back pain: results of a systematic review

BACKGROUND CONTEXT

Low back pain (LBP) is a disorder that commonly affects the working population, resulting in disability, health-care utilization, and a heavy socioeconomic burden. Although the etiology of LBP remains uncertain, occupational activities have been implicated. Evaluating these potentially causal relationships requires a methodologically rigorous approach. Occupational repetitive and/or heavy lifting is widely thought to be a risk factor for the development of LBP.

PURPOSE

To conduct a systematic review of the scientific literature to evaluate the causal relationship between occupational lifting and LBP.

STUDY DESIGN

Systematic review of the literature.

SAMPLE

Studies reporting an association between occupational lifting and LBP.

OUTCOME MEASURES

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

METHODS

A search was conducted using Medline, EMBASE, CINAHL, Cochrane Library, OSH-ROM, gray literature (eg, reports not published in scientific journals), hand-searching occupational health journals, reference lists of included studies, and content experts. Evaluation of study quality was performed using a modified version of the Newcastle-Ottawa Scale. Levels of evidence were evaluated for specific Bradford-Hill criteria (association, dose-response, temporality, experiment, and biological plausibility).

RESULTS

This search yielded 2,766 citations, of which 35 studies met eligibility criteria and 9 were considered high methodological quality studies, including four case-controls and five prospective cohorts. Among the high-quality studies, there was conflicting evidence for association with four studies reporting significant associations and five studies reporting nonsignificant results. Two of the three studies that assessed dose-response demonstrated a nonsignificant trend. There were no significant risk estimates that demonstrated temporality. No studies were identified that satisfied the experiment criterion. Subgroup analyses identified certain types of lifting and LBP that had statistically significant results, but there were none that satisfied more than two of the Bradford-Hill criteria.

CONCLUSIONS

This review uncovered several high-quality studies examining a relationship between occupational lifting and LBP, but these studies did not consistently support any of the Bradford-Hill criteria for causality. There was moderate evidence of an association for specific types of lifting and LBP. Based on these results, it is unlikely that occupational lifting is independently causative of LBP in the populations of workers studied. Further research in specific subcategories of lifting would further clarify the presence or absence of a causal relationship.

Causal assessment of occupational pushing or pulling and low back pain: results of a systematic review

BACKGROUND CONTEXT

Low back pain (LBP) is a prevalent and expensive musculoskeletal condition that predominantly occurs in working-age individuals of industrialized nations. Although numerous occupational physical activities have been implicated in its etiology, determining the causation of occupational LBP still remains a challenge.

PURPOSE

To conduct a systematic review evaluating the causal relationship between occupational pushing or pulling and LBP.

STUDY DESIGN

Systematic review of the literature.

SAMPLE

Studies reporting an association between occupational pushing or pulling and LBP.

OUTCOME MEASURES

Numerical association between exposure to pushing or pulling and the presence 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 for causation for occupational pushing or pulling and LBP. A search was conducted using Medline, EMBASE, CINAHL, Cochrane Library, and OSH-ROM, gray literature, hand-searching occupational health journals, reference lists of included studies, and expert knowledge. Methodological quality was assessed using a modified Newcastle-Ottawa Scale.

RESULTS

This search yielded 2,766 citations. Thirteen studies met the inclusion criteria. Eight were high-quality studies and five were low-quality studies. There was conflicting evidence with one high-quality study demonstrating a positive association between occupational pushing or pulling and LBP and five studies showing no relationship. One study reported a nonstatistically significant dose-response trend, four studies discussed temporality of which one indicated a positive finding, two studies discussed the biological plausibility of a causal link between occupational pushing or pulling and LBP, and no evidence was uncovered to assess the experiment criterion.

CONCLUSIONS

A qualitative summary of existing studies was not able to find any high-quality studies that fully satisfied any of the Bradford-Hill causation criteria for occupational pushing or pulling and LBP. Based on the evidence reviewed, it is unlikely that occupational pushing or pulling is independently causative of LBP in the populations of workers studied.

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

BACKGROUND CONTEXT

Low back pain (LBP) is a common and disabling musculoskeletal disorder that often occurs in a working-age population. Determining the precise causation of LBP remains difficult. Any attempt to implicate a specific occupational activity in the genesis of LBP requires a methodologically rigorous approach.

PURPOSE

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

STUDY DESIGN

Systematic review of the literature using Medline, EMBASE, CINAHL, Cochrane Library, Occupational Safety and Health database, grey literature, hand-searching occupational health journals, reference lists of included studies, and content experts. Evaluation of study quality using a modified version of the Newcastle-Ottawa Scale. Summary levels of evidence supporting Bradford-Hill criteria for different categories of sitting and types of LBP.

SAMPLES

Studies reporting an association between occupational sitting and LBP.

OUTCOME MEASURES

Numerical association between different levels of exposure to occupational sitting 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 sitting and LBP.

RESULTS

This search yielded 2,766 citations. Twenty-four studies met the inclusion/exclusion criteria and five were high-quality studies, including two case-controls and three prospective cohorts. Strong, consistent evidence was found for no association between occupational sitting and LBP. A moderate level of evidence was found for the absence of any dose-response trend. Risk estimates evaluating temporality were not statistically significant. Biological plausibility was not discussed in these studies. No evidence was available to assess the experiment criterion.

CONCLUSIONS

This review failed to uncover high-quality studies to support any of the Bradford-Hill criteria to establish causality between occupational sitting and LBP. Strong and consistent evidence did not support criteria for association, temporality, and dose response. Based on these results, it is unlikely that occupational sitting is independently causative of LBP in the populations of workers studied.

Causal assessment of occupational standing or walking and low back pain: results of a systematic review

BACKGROUND CONTEXT

Low back pain (LBP) is a widespread musculoskeletal condition that frequently occurs in the working-age population. Numerous occupational physical activities have been implicated in its etiology.

PURPOSE

To conduct a systematic review establishing a causal relationship between occupational standing or walking and LBP.

STUDY DESIGN

Systematic review of the literature.

SAMPLE

Studies reporting an association between occupational standing or walking and LBP.

OUTCOME MEASURES

Numerical association between exposure to standing or walking and the presence 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 for causality, between occupational standing or walking and LBP. A search was conducted 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 expert knowledge. Evaluation of methodological quality was performed using a modified Newcastle-Ottawa Scale.

RESULTS

This search yielded 2,766 citations. Eighteen studies met the inclusion criteria. Five were high-quality studies related to standing, and two were high-quality studies related to walking. For occupational standing and LBP, there was moderate to strong evidence against the association criterion, the only study examining dose response did not support this criterion, four studies examining temporality failed to support this criterion, and only one study discussed the biological plausibility criterion. For occupational walking and LBP, there was moderate evidence against a causal relationship with respect to the association, temporality, dose response, and biological plausibility criteria. No studies assessed the experiment criterion for these activities.

CONCLUSIONS

A summary of existing studies was not able to find any high-quality studies that satisfied more than two of the Bradford-Hill causation criteria for occupational standing or walking and LBP. Based on the evidence reviewed, it is unlikely that occupational standing or walking is independently causative of LBP in the populations of workers studied.

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

BACKGROUND CONTEXT

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

PURPOSE

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

STUDY DESIGN

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 awkward occupational posture and type of LBP.

SAMPLE

Studies reporting an association between awkward occupational postures and LBP.

OUTCOME MEASURES

Numerical association between different levels of exposure to awkward occupational postures 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 awkward occupational postures and LBP.

RESULTS

This search yielded 2,766 citations. Eight high-quality studies reported on awkward occupational postures and LBP. Three were case-control studies, one was cross-sectional, and four were prospective cohort studies. There was strong evidence for consistency of no association between awkward occupational postures and LBP, with only two studies demonstrating significant associations in most of their risk estimates compared with six studies reported mainly nonsignificant associations. Two studies assessed dose response, with one study demonstrating a nonsignificant dose-response trend. Three studies were able to assess temporality, but all demonstrated nonsignificant risk estimates. Biological plausibility was discussed by two studies. There was no available evidence to assess the experiment criterion for causality.

CONCLUSIONS

There was strong evidence from six high-quality studies that there was no association between awkward postures and LBP. Similarly, there was strong evidence from three high-quality studies that there was no temporal relationship. Moreover, subgroup analyses identified only a handful of studies that demonstrated only weak associations and no evidence for other aspects of causality in certain specific subcategories. It is therefore unlikely that awkward occupational postures are 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.

Does physical activity change predict functional recovery in low back pain? Protocol for a prospective cohort study

BACKGROUND

Activity advice and prescription are commonly used in the management of low back pain (LBP). Although there is evidence for advising patients with LBP to remain active, facilitating both recovery and return to work, to date no research has assessed whether objective measurements of free living physical activity (PA) can predict outcome, recovery and course of LBP.

METHODS

An observational longitudinal study will investigate PA levels in a cohort of community-dwelling working age adults with acute and sub-acute LBP. Each participant's PA level, functional status, mood, fear avoidance behaviours, and levels of pain, psychological distress and occupational activity will be measured on three occasions during for 1 week periods at baseline, 3 months, and 1 year. Physical activity levels will be measured by self report, RT3 triaxial accelerometer, and activity recall questionnaires. The primary outcome measure of functional recovery will be the Roland Morris Disability Questionnaire (RMDQ). Free living PA levels and changes in functional status will be quantified in order to look at predictive relationships between levels and changes in free living PA and functional recovery in a LBP population.

DISCUSSION

This research will investigate levels and changes in activity levels of an acute LBP cohort and the predictive relationship to LBP recovery. The results will assess whether occupational, psychological and behavioural factors affect the relationship between free living PA and LBP recovery. Results from this research will help to determine the strength of evidence supporting international guidelines that recommend restoration of normal activity in managing LBP.

TRIAL REGISTRATION

[Clinical Trial Registration Number, ACTRN12609000282280].

A biomechanical analysis of anterior load carriage

Front load carriage is a common occupational task in some industries (e.g. agriculture, construction), but, as compared to lifting tasks, relatively little research has been conducted on the biomechanical loading during these activities. The focus of this study was to explore the low back biomechanics during these activities and, specifically, to examine the effects of load height and walking speed on trunk muscle activity and trunk posture. Eleven male participants participated in two separate front load-carriage experiments. The first experiment called for carrying a barbell (with weight corresponding to 20% of elbow flexion strength) at three heights (knuckle height, elbow height and shoulder height) at a constant horizontal distance from the spine. The second experiment called for participants to carry a bucket of potatoes weighing 14 kg at the same three heights, but with no further restrictions in technique. In both experiments, the participants performed this task while either standing still or walking at a self-selected speed. As they performed these tasks, the activity levels of the right-side muscle of the rectus abdominis, external oblique, biceps brachii, anterior deltoid and three levels (T9, T12 and L3) of the erector spinae were sampled. Mid-sagittal plane trunk posture was also quantified using three magnetic field-based motion sensors at T9, T12 and L3. The results showed a significant effect of both walking speed and load height on trunk posture and trunk muscle activity levels in both the barbell and bucket experiments. In the barbell experiment, the walking trials generated 43% more trunk muscle activity than the standing trials. Trials at shoulder height produced 11% more muscle activity than trials at elbow height in the T9 erector spinae muscles and 71% more muscle activity in the anterior deltoid. In the bucket experiment, trunk muscle activity responded in a similar fashion, but the key result here was the quantification of the natural hyperextension posture of the spine used to balance the bucket of potatoes. These results provide insight into muscle activation patterns in dynamic settings, especially (load) carrying biomechanics, and have implications in industrial settings that require workers to carry loads in front of their bodies.

The prevalence of low back pain in Africa: a systematic review

Background

Low back pain (LBP) is the most prevalent musculoskeletal condition and one the most common causes of disability in the developed nations. Anecdotally, there is a general assumption that LBP prevalence in Africa is comparatively lower than in developed countries. The aim of this review was to systematically appraise the published prevalence studies conducted on the African continent to establish the prevalence of LBP in Africa.

Methods

A comprehensive search was conducted in April 2006. The following databases PEDro, Psychinfo, Science Direct, SportsDiscus, PubMed, CINAHL, Biblioline Pro-African Wide NiPAD and SA ePublications were individually searched using specifically developed search strategies for epidemiological research conducted on LBP amongst the African population. Two reviewers independently evaluated the methodological quality of the studies reviewed.

Results

A total of 27 eligible epidemiological studies were included in this review. The majority of the studies (63%) were conducted in South Africa (37%) and Nigeria (26%). The most common population group involved workers (48%), while scholars comprised 15% of the population. 67% of the studies were found to be methodologically sound, and the LBP prevalence of these were analyzed. The mean LBP point prevalence among the adolescents was 12% and among adults was 32%. The average one year prevalence of LBP among adolescents was 33% and among adults was 50%. The average lifetime prevalence of LBP among the adolescents was 36% and among adults was 62%.

Conclusion

The findings support the global burden of disease of LBP, in addition to suggesting that LBP prevalence among Africans is rising and is of concern. Further research into the most effective strategies to prevent and manage LBP in Africa is warranted.