Repetitive industrial work and neck and upper limb disorders in females

Sleep quality and sleep-related issues in industrial workers: a global meta-analysis

Objectives. Sleep-related issues are important health issues. This study aimed to investigate the global prevalence of sleep-related issues in industrial workers. Methods. A syntax of keywords was used to search the PubMed, Web of Science and Scopus databases. The search time was limited to articles published until September 2020, and the search range was in English. Events and samples were extracted for each study to calculate the prevalence. For all subgroups, events and samples were extracted to calculate the results of the subgroups. The random-effects method was used in the analysis. Heterogeneity was examined at the levels of all analyses. Results. Forty-eight articles were included in the analysis as eligible studies. Sleep-related issues have 30% prevalence in the 95% confidence interval (CI) [25, 35%]. The prevalence of sleep-related issues in men was 38%, 95% CI [31, 45%] and in women was 32%, 95% CI [14, 50%]. The prevalence of poor sleep quality, insomnia, sleep duration <7 h, snoring and sleepiness was 36, 22, 37, 29 and 10%, respectively. Conclusions. Sleep-related issues have a high prevalence in industrial workers, and the cause of these differences needs to be addressed and increasing insights provided to prevent and treat sleep disorders.

Three-Dimensional Video Microscopy: Potential for Improved Ergonomics without Increased Operative Time?

Three-dimensional (3D) video exoscopes are high-magnification stereo cameras that project onto monitors mounted in the operating room, viewable from different angles. Outside of plastic surgery, exoscopes have been shown to successfully improve the ergonomics of microsurgery, though sometimes with prolonged operating times. We compare a single surgeon's early experience performing free flap procedures from 2020 to 2021 using either a binocular microscope or a 3D video exoscope. Ten procedures were performed with the standard operating microscope and 8 procedures with the 3D exoscope. The microsurgeon, having minimal prior experience using an exoscope, reported less neck discomfort following the free flap procedures performed with the exoscope compared with the binocular surgical microscope. Total average operating time was comparable between the standard surgical microscope and the 3D exoscope (13.7 vs. 13.4 hours, p  = 0.34). Our early experience using a 3D exoscope in place of a standard optical microscope demonstrated that the exoscope shows promise, offering an ergonomic alternative during microvascular reconstruction without increasing overall operating times. Future studies will compare free flap ischemia time between cases performed using the exoscope and the conventional binocular microscope. Medical Subject Headings authorized following words: free tissue flaps; operating rooms; ergonomics; microsurgery.

Job-related stress associated with work-related upper extremity musculoskeletal disorders (UEMDs) in municipal waste collectors: the moderation and mediation effect of job support

Background

Since the policy of “keeping trash off of the ground” in Taiwan, long-term exposure to repetitive motion in waste collection process results in high risk of upper extremity musculoskeletal disorders (UEMDs). Thus, we assessed the moderation and mediation effects of job-related stress and job support on work-related UEMDs among municipal waste collectors.

Methods

A cross-sectional study was conducted in two cities located at northern Taiwan during 2018–2019. 626 municipal waste collectors voluntarily participated and anonymously filled out a structured questionnaire. The moderation and mediation effects of effort-reward imbalance (ERI) and social support on UEMDs were analyzed by Haye’s Process Macro Model.

Results

Prevalence of UEMDs in municipal waste collectors were 43.4% for neck, 56.0% for shoulder, 24.1% for upper back, and 33.1% for hand/wrist. There was high prevalence of shoulder (72.2%), neck (48%), and upper back (30%) in female workers compared to male, most significantly in shoulders. In univariate and multivariate analysis, high ERI and low job support were significantly associated with ORs of 3.11 (95% CI:1.58–6.13) for elbow, 2.79 (95% CI:1.39–5.56) for shoulder, 3.39 (95% CI:1.64–7.00) for upper back and 3.83 (95% CI:1.98–7.41) for hand/wrist. Prevalent UEMDs were positively associated with high ERI in municipal waste collectors but negatively with job support. The moderation effects of ERI and job support on UEMDs, of which the measured synergy index exceeded one, were 18.24 for shoulder, 3.32 for elbow, and 2.45 for hand/wrist, but mediation effects were not significant.

Conclusions

This study found municipal waste collectors with work-related upper extremity disorders were significantly associated with work-related psychological risk factors. Therefore, waste collection cannot only to be improved by semi-automatic and automatic processes but immediate intervention programs for the reduction of psychological risk factors is needed promptly.

Occupational ergonomic assessment of MSDs among the artisans working in Bagh hand block printing industry in Madhya Pradesh, India

PURPOSE

Hand block printing technique practiced in Dhar District of Madhya Pradesh (M.P.) involves highly repetitive tasks with awkward posture, which contribute to the development of musculoskeletal disorders (MSDs) among the artisans, The aim of this study was to determine the prevalence of MSDs and the risks factors involved. Materials and methods: an observational study and a self-reported questionnaire study were conducted with a sample of 70 artisans. The working postures of the artisans were analyzed using Rapid upper limb assessment (RULA) and Occupational repetitive actions method (OCRA). p ≤ 0.05 was considered significant throughout the study.

RESULTS

MSDs in the neck, shoulders, elbows, wrist/forearm, Lower back, and Hips/Thighs were found to be highly prevalent among artisans of age greater than 31 and experience greater than 11. Most complaints were reported in the wrist, neck and lower back region.

CONCLUSION

From the findings, it was evident that artisans working in Bagh printing are at high risk of the development of MSDs; thus, an immediate intervention is needed to eliminate the ergonomic risks among the artisans.

Assessment of Joint Angle and Reach Envelope Demands Using a Video-Based Physical Demands Description Tool

BACKGROUND

Current methods for describing physical work demands often lack detail and format standardization, require technical training and expertise, and are time-consuming to complete. A video-based physical demands description (PDD) tool may improve time and accuracy concerns associated with current methods.

METHODS

Ten simulated occupational tasks were synchronously recorded using a motion capture system and digital video. The tasks included a variety of industrial tasks from lifting to drilling to overhead upper extremity tasks of different cycle times. The digital video was processed with a novel video-based assessment tool to produce 3D joint trajectories (PDAi), and joint angle and reach envelope measures were calculated and compared between both data sources.

RESULTS

Root mean squared error between video-based and motion capture posture estimated ranged from 89.0 mm to 118.6 mm for hand height and reach distance measures, and from 13.5° to 21.6° for trunk, shoulder, and elbow angle metrics. Continuous data were reduced to time-weighted bins, and video-based posture estimates showed 75% overall agreement and quadratic-weight Cohen's kappa scores ranging from 0.29 to 1.0 compared to motion capture data across all posture metrics.

CONCLUSION AND APPLICATION

The substantial level of agreement between time-weighted bins for video-based and motion capture measures suggest that video-based job task assessment may be a viable approach to improve accuracy and standardization of field physical demands descriptions and minimize error in joint posture and reach envelope estimates compared to traditional pen-and-paper methods.

Exploring the relationship between neck flexion and neck problems in occupational populations: a systematic review of the literature

A systematic review was conducted to evaluate the relationship between occupational neck flexion angles and neck problems. The synthesised findings were used to answer three research questions: (1) Is there a positive/negative relationship between neck flexion and neck problems? (2) What is the appropriate angular threshold for neck flexion as a risk factor for neck problems? (3) What are the gaps in our current knowledge? A review of 21 papers revealed (1) a consistent positive correlation between neck flexion and neck problems, and (2) a neck flexion angle of 20° as the most evidence-based (not necessarily the best) cut-off angle separating high- and low-risk neck flexion postures. Future research should focus on the (1) continuous collection of three-dimensional neck postures through longitudinal studies to quantify cumulative exposures of neck postures, and (2) development of standard descriptions of 'neck problems' and 'neck flexion' to facilitate the development of a dose-response relationship. Practitioner summary: Practitioners depend on thresholds for evaluating neck postural exposure using work assessment tools; however, the scientific basis for this is unclear. This systematic review investigated the angular threshold for neck flexion and found 20° of neck flexion with the greatest evidence-based support as the threshold for high-risk neck postural exposure.

Predictors for Clinical Outcomes Related to Upper Extremity Musculoskeletal Disorders in a Healthy Working Population

A wide range of endpoints and methods of analysis can be observed in occupational health studies in the context of work-related musculoskeletal disorders (WMSDs). Comparison of study results is therefore difficult. We investigated the association between different clinical endpoints and the presence of upper extremity WMSDs in a healthy working population. Furthermore, the influence of socio-demographic, work-related, and individual predictors on different endpoints was examined. Two self-administered questionnaires were distributed to 70 workers and employees. In addition, a standardized physical examination and an industry test were performed in this cross-sectional study. Correlations between WMSDs and clinical endpoints were analyzed with the Spearman method and prediction ellipses. Multiple regression models were used to study the strength of associations with a pre-defined set of potential influencing factors. The prevalence of WMSDs was 56% (39/70). Disabilities of Arm, Shoulder, and Hand (DASH) score/pain under strain showed the strongest correlations with WMSDs. When analyzing the correlation between WMSDs and pre-selected predictors, none of the predictors could be identified as a risk factor. The DASH score remains a close candidate for best surrogate endpoint for WMSDs detection. Standardized analysis methods could improve the methodological quality of future occupational health studies.

An investigation of an ergonomics intervention to affect neck biomechanics and pain associated with smartphone use

BACKGROUND

Neck discomfort and pronounced neck flexion have been associated with smartphone use.

OBJECTIVE

Eye glasses with a 90 deg prism in each lens were investigated as a potential intervention to reduce awkward head and neck postures during activities involving viewing the device.

METHODS

Sixteen smartphone users with neck pain and 9 asymptomatic users performed a texting task on a smartphone with and without the prism glasses, in sitting and standing postures in a laboratory setting.

RESULTS

Cervical erector spinae and upper trapezius muscle activity, head posture and motion, performance, discomfort and other subjective perceptions were assessed. Prism glasses reduced neck extensor muscle activity, neck flexion, and head tilt compared to the direct view. In the symptomatic group, the intervention produced less neck and shoulder discomfort compared to the direct view.

CONCLUSIONS

This intervention could offer an alternative way of interacting with a smartphone while texting in stationary postures, by reducing exposure to pronounced flexed neck and head posture commonly seen in users, and thereby could reduce neck discomfort associated with smartphone use.

The Dynamic Computer Workstation-A Pilot Study of Clinical and Biochemical Investigation during Work at Static Respectively Mobile Keyboards

A large and increasing number of the work force in the population spend their work hours at the keyboard. There is evidence that repetitive high levels of static work, or extreme working postures involving the neck-shoulder muscles are an increased risk for chronic neck-shoulder pain. The aim of this study was to investigate the effect of dynamic computer working (DCW), using a mobile application to the desk surface, on pain characteristics and biomarkers in office workers. We included 10 female subjects. All subjects answered questionnaires about general health, pain intensity and characteristics. The pressure pain threshold (PPT), neck range and motion, neck and shoulder strength were measured. Microdialysis was conducted in trapezius muscle. Measurements were performed before and 4 weeks after DCW. Multivariate analysis, orthogonal partial least square discriminate analysis (OPLS-DA) and univariate analysis paired test, Wilcoxon, was performed. There was significant improvement in reported neck pain, quality of life, and psychological distress after 4 weeks DCW. The PPT and strength in neck and shoulder were significantly increased after DCW. A significant OPLS-DA model showed clear separation between the samples collected before and after 4 weeks DCW. In conclusion, these results show that keyboard work at a movable desk application might decrease the risk of repetitive strain injuries in the neck and shoulder muscles.

Comparative Assessment of Ergonomic Experience with Heads-Up Display and Conventional Surgical Microscope in the Operating Room

PURPOSE

Musculoskeletal pain issues are prevalent in ophthalmic surgeons and can impact surgeon well-being and productivity. Heads-up displays (HUD) can improve upon conventional microscopes by reducing ergonomic stress. This study compared ergonomic outcomes between HUD and a conventional optical microscope in the operating room, as reported by ophthalmic surgeons in the US.

METHODS

An online questionnaire was distributed to a sample of surgeons who had experience operating with HUD. The questionnaire captured surgeon-specific variables, the validated Nordic Musculoskeletal Questionnaire, and custom questions to compare HUD and conventional microscope. A multivariable model was built to identify variables that were likely to predict improvement in pain-related issues.

RESULTS

Analysis was conducted on 64 surgeons (37 posterior-segment, 25 anterior-segment, and two mixed) with a mean 14.9 years of practice and 2.3 years using HUD. Most surgeons agreed or strongly agreed that HUD reduced the severity (64%) and frequency (63%) of pain and discomfort, improved posture (73%), and improved overall comfort (77%). Of respondents who experienced headaches, or pain and discomfort during operation, 12 (44%) reported their headaches improved and 45 (82%) reported feeling less pain and discomfort since they started using HUD. The multivariable model indicated the odds of reporting an improvement in pain since introducing the HUD in the operating room were 5.12-times greater for those who used HUD in >50% of their cases (P=0.029).

CONCLUSION

This study indicates that heads-up display may be an important tool for wellness in the operating room as it can benefit ophthalmic surgeons across several ergonomic measures.

Stretching and Strength Training to Improve Postural Ergonomics and Endurance in the Operating Room

Plastic surgeons report the highest prevalence of chronic musculoskeletal pain and fatigue among surgical subspecialties. Musculoskeletal pain impacts daily life, career longevity, and economic burden secondary to occupational injury. Poor postural awareness and ergonomic set up in the operating room represent the most common etiology.

Methods

A literature review was performed to highlight the ergonomic set-up, postural pitfalls, occupational injuries, and musculoskeletal pain in the operating room. An institutional survey was administered among resident and attending surgeons regarding musculoskeletal pain, posture, ergonomic education, and future improvements. Literature results, survey data, and intraoperative photographs were analyzed in collaboration with physical therapists and personal trainers.

Results

Survey results demonstrated that 97% of resident and attending respondents experienced musculoskeletal pain and 83% reported a lack of education in posture and ergonomics. The main postural pitfalls included head forward and flexed positioning, abduction and internal arm rotation, and kyphosis of the thoracic spine. The collaborators developed instructional videos to assess posture and biomechanics and demonstrate targeted stretching and strength exercises to address specific neck, back, and shoulder pain.

Conclusions

Poor posture is unavoidable in the operating room at times. These educational videos should be utilized for self-motivated and prophylactic conditioning outside of the operating room to maintain physical well-being throughout a career in plastic surgery. Future focus should be aimed at implementing dedicated ergonomic education and physical wellness programs early in surgical resident training.

An Objective Ergonomic Risk Assessment of Surgeons in Real Time While Performing Endoscopic Sinus Surgery

There are increased reports of high prevalence of work related musculoskeletal symptoms in surgeons performing otolaryngology procedures. However, real time ergonomic risk assessment in the OR is difficult due to issues related to sterility, cooperation and acceptance from surgeons. Although such analyses can provide valid risk estimate and guide corrective actions, they are scarce. Hence, this study was undertaken to assess the postural ergonomic risk on RULA in otolaryngologists while performing Functional Endoscopic Sinus Surgery in OR, in real time. A cross sectional, observational multi-centric study was conducted in tertiary referral hospitals. Spinal, shoulder and elbow movements of 10 surgeons performing FESS were measured intraoperatively using orientation sensor-based, motion-analysis system (Noraxon myomotion). Postural ergonomic risk on RULA was computed using the motion analysis data. RULA is a method of quantifying the physical postural risk of the trunk and upper limb based on the postures adopted by an individual during work. 10 surgeons (9 males and 1 female) with the mean (± SD) age of 38 ± 7.5 years participated in the study. The motion analysis data results indicate that the surgeons often adopt awkward spinal and upper extremity postures during the surgery. All the surgeons scored higher than the acceptable RULA score (1 or 2) with the mean RULA scores being in the range of 6-7. The physical ergonomic risk in surgeons performing FESS is high (> 6 on RULA). There is a need for urgent ergonomic attention to the working environment of FESS surgeon.

[Neck pain among tobacco farm workers in Southern Brazil]

This study aims to assess neck pain prevalence and associated factors among tobacco farm workers. This is a cross-sectional study of 2,469 tobacco farm workers in southern Brazil. An adapted version of the Nordic Questionnaire of Musculoskeletal Symptoms was used to characterize neck pain. Multivariate analysis was performed using Poisson regression, following a hierarchical theoretical model. Neck pain prevalence in the last year among the population studied was 7.4%. Worker age, tobacco smoking, tobacco bundling, use of heavy chainsaws, working at an intense or accelerated pace and green tobacco sickness were variables associated with neck pain in females. Among males, age, use of heavy chainsaws, working in a sitting position on the ground, pesticide poisoning, and green tobacco sickness were associated with the outcome. The study reinforces the importance of ergonomic and physiological workloads in the determination of neck pain. Future studies are needed to understand the role of pesticides and nicotine exposures on musculoskeletal problems. The mechanization of tobacco harvesting could reduce ergonomic and chemical exposure, thereby improving farmers' health.

Is Repetitive Workload a Risk Factor for Upper Extremity Musculoskeletal Disorders in Surgical Device Mechanics? A Cross-Sectional Analysis

To assess the prevalence of upper extremity work-related musculoskeletal disorders (WMSDs) among surgical device mechanics compared to a control group, a total of 70 employees were included and assigned to three occupational groups (grinders, packers, and control). Personal factors, work exposure, manual skill, and complaints were assessed by two self-administered questionnaires and an industry test. WMSDs were diagnosed in a standardised clinical examination. The two-one-sided t-tests (TOST) procedure was used to test the clinical equivalence of the respective grinding and packaging groups vs. the control group in terms of the Disabilities of the Arm, Shoulder and Hand (DASH) score. Thirty-nine study participants (56%) experienced at least one WMSD at the elbow, forearm, and/or wrist, mainly with signs of epicondylitis and nerve entrapment at the medial elbow. The risk of grinders developing upper extremity WMSD was about 2.5-times higher and packers had an 8.6-fold higher risk of a clinically relevant DASH > 29 compared to the control group. However, these differences were not statistically significant. The groups were also proven to be clinically equivalent in terms of DASH score. Surgical device mechanics do not seem to have worse DASH values or be at higher risk of upper limb WMSDs compared to a control group. This is the first study to analyse and compare different workplaces in this industry that are also common in other industries.

The Impact of Cervical Musculoskeletal Disorders on UK Consultant Plastic Surgeons: Can We Reduce Morbidity With Applied Ergonomics?

BACKGROUND

Based on anecdotal and observational evidence, we hypothesized that the prevalence of cervical musculoskeletal disorder (C-MSD) would be high among plastic surgeons. A questionnaire review was undertaken to test this hypothesis. Ergonomic assessment was undertaken to assess causal factors of C-MSD.

METHOD

An anonymous questionnaire recording demographics, physical symptoms and behavioral responses to C-MSD was distributed to UK Plastic Surgery consultants. The postural impact of wearing loupes was assessed using motion capture techniques and recording cervical muscular activity.

RESULTS

The questionnaire response rate was 81%. The prevalence of cervical spine morbidity was recorded as 32%. Employment implications included 28% of the cohort requiring sick leave. The professional impact was 7% permanently modifying their practice. There were 2 factors significant for C-MSD, the surgeons' age and the duration in hours of wearing loupes per week. Ergonomic assessment of surgeons operating in loupes demonstrated: 1. increased forward and lateral cervical flexion; 2. increased cervical muscular activity to maintain the protracted "head forward" posture; and 3. prolonged static posturing to maintain head position for visual focus. Table height adjustment and variation of loupe working distance can reduce neck flexion.

CONCLUSIONS

Cervical morbidity is a prevalent problem among plastic surgeons. Long procedures, static postures and neck flexion result in the "head forward" posture. This posture exaggerates when operating with loupe magnification. Early-middle-aged consultants are more prone to cervical morbidity hence afflicted when at the top of their game. The work force is diminished for a potentially avoidable morbidity. Rather than accept this morbidity, co-operation between plastic surgeons and ergonomist may help to reduce injury.

Development and evaluation of a soft wearable weight support device for reducing muscle fatigue on shoulder

Compensating the weight of human limbs is important in reducing muscle fatigue experienced by manual laborers. In this study, a compact and lightweight soft wearable weight support device was developed and evaluated. The device supports gravitational force on the shoulder at any arm posture, although there are some limitations in its assistive performance. The device actuator consists of a cam-rod structure, a tendon-driven mechanism, and a rubber band. The desired assistive torque is translated to the shoulder joint along a tendon routing structure. Device performance was evaluated by measuring muscle activation in with-assist and without-assist conditions. Muscle activation on the deltoid was measured by surface electromyography. An experimental protocol consisting of a series of exercises was executed with six healthy subjects. The subjects raised and lowered their arm from 0 to 100 degrees for 30 times under eight conditions, which were combined with-assist and without-assist conditions, and holding the horizontal angle of the arm at 0, 30, 60, or 90 degrees against the sagittal plane. Surface electromyography data were pre-processed and analyzed using a root mean square method. When muscle fatigue occurs, the root mean square of the surface electromyography increases nonlinearly. This was calculated using the standard deviation of the root mean square. Three of six subjects showed decreased variation of the root mean square between the exercises in the with-assist condition. One subject’s result was significantly reduced (by about 57.6%) in the with-assist condition. In contrast, two subjects did not show significant difference between measurements taken in the with-assist and without-assist conditions. One subject was dropped from the experiment because the device did not fit the subject’s body. In conclusion, the effectiveness of the soft wearable weight support device in supporting shoulder movements was verified through the decreased variation of muscle activation.

Exposure-response relationships for work-related neck and shoulder musculoskeletal disorders--Analyses of pooled uniform data sets

There is a lack of quantitative data regarding exposure-response relationships between occupational risk factors and musculoskeletal disorders in the neck and shoulders. We explored such relationships in pooled data from a series of our cross-sectional studies. We recorded the prevalence of complaints/discomfort (Nordic Questionnaire) and diagnoses (physical examination) in 33 groups (24 female and 9 male) within which the workers had similar work tasks (3141 workers, of which 817 were males). In representative sub-groups, we recorded postures and velocities of the head (N = 299) and right upper arm (inclinometry; N = 306), right wrist postures and velocities (electrogoniometry; N = 499), and muscular activity (electromyography) in the right trapezius muscle (N = 431) and forearm extensors (N = 206). We also assessed the psychosocial work environment (Job Content Questionnaire). Uni- and multivariate linear meta-regression analysis revealed several statistically significant group-wise associations. Neck disorders were associated with head inclination, upper arm elevation, muscle activity of the trapezius and forearm extensors and wrist posture and angular velocity. Right-side shoulder disorders were associated with head and upper arm velocity, activity in the trapezius and forearm extensor muscles and wrist posture and angular velocity. The psychosocial work environment (low job control, job strain and isostrain) was also associated with disorders. Women exhibited a higher prevalence of neck and shoulder complaints and tension neck syndrome than men, when adjusting for postures, velocities, muscular activity or psychosocial exposure. In conclusion, the analyses established quantitative exposure-response relationships between neck and shoulder disorders and objective measures of the physical workload on the arm. Such information can be used for risk assessment in different occupations/work tasks, to establish quantitative exposure limits, and for the evaluation of preventive measures.

Secretory leukocyte protease inhibitor (SLPI), a multifunctional protein in the host defense response

Secretory leukocyte protease inhibitor (SLPI), a ∼12kDa nonglycosylated cationic protein, is emerging as an important regulator of innate and adaptive immunity and as a component of tissue regenerative programs. First described as an inhibitor of serine proteases such as neutrophil elastase, this protein is increasingly recognized as a molecule that benefits the host via its anti-proteolytic, anti-microbial and immunomodulatory activities. Here, we discuss the diverse functions of SLPI. Moreover, we review several novel layers of SLPI-mediated control that protect the host from excessive/dysregulated inflammation typical of infectious, allergic and autoinflammatory diseases and that support healing responses through affecting cell proliferation, differentiation and apoptosis.

Electrophysiological characteristics according to activity level of myofascial trigger points

[Purpose] This study compared the differences in electrophysiological characteristics of normal muscles versus muscles with latent or active myofascial trigger points, and identified the neuromuscular physiological characteristics of muscles with active myofascial trigger points, thereby providing a quantitative evaluation of myofascial pain syndrome and clinical foundational data for its diagnosis. [Subjects] Ninety adults in their 20s participated in this study. Subjects were equally divided into three groups: the active myofascial trigger point group, the latent myofascial trigger point group, and the control group. [Methods] Maximum voluntary isometric contraction (MVIC), endurance, median frequency (MDF), and muscle fatigue index were measured in all subjects. [Results] No significant differences in MVIC or endurance were revealed among the three groups. However, the active trigger point group had significantly different MDF and muscle fatigue index compared with the control group. [Conclusion] Given that muscles with active myofascial trigger points had an increased MDF and suffered muscle fatigue more easily, increased recruitment of motor unit action potential of type II fibers was evident. Therefore, electrophysiological analysis of these myofascial trigger points can be applied to evaluate the effect of physical therapy and provide a quantitative diagnosis of myofascial pain syndrome.

Reliability and Limits of Agreement of the Supraspinatus Muscle Anatomical Cross-Sectional Area Assessment by Ultrasonography

The purpose of this study was to evaluate the reliability and limits of agreement for assessment of the anatomical cross-sectional area (ACSA) of the supraspinatus muscle using B-mode ultrasonography. Sixteen participants were examined with two different protocols, on two different days. There were no statistically significant differences (p > 0.05) in ACSA values between days 1 and 2 or between protocols 1 and 2; the average intra-class correlation coefficient ranged from 0.93 to 0.96. The limits of agreement for supraspinatus ACSA were, in both protocols, about ± 1 cm(2). Our findings revealed that both protocols had high reliability in distinguishing differences of about 1 cm(2) between groups or after interventions and that ultrasonography can be used for experimental designs in which the expected changes in ACSA would be higher than 14%.

Shoulder disorders and occupation

Shoulder pain is very common, and it causes substantial morbidity. Standardised classification systems based upon presumed patho-anatomical origins have proved poorly reproducible and hampered epidemiological research. Despite this, there is evidence that exposure to combinations of physical workplace strains such as overhead working, heavy lifting and forceful work as well as working in an awkward posture increases the risk of shoulder disorders. Psychosocial risk factors are also associated. There is currently little evidence to suggest that either primary prevention or treatment strategies in the workplace are very effective, and more research is required, particularly around the cost-effectiveness of different strategies.

Brachial plexopathy: a case-control study of the relation to physical exposures at work

BACKGROUND

Work-related upper limb disorders constitute a diagnostic challenge. However, patterns of neurological abnormalities that reflect brachial plexus dysfunction are frequent in limbs with pain, weakness and/or numbness/tingling. There is limited evidence about the association between occupational physical exposures and brachial plexopathy.

METHODS

80 patients with brachial plexopathy according to defined criteria and 65 controls of similar age and sex without upper limb complaints were recruited by general practitioners. Patients and controls completed a questionnaire on physical and psychosocial work-exposures and provided psychophysical ratings of their perceived exposures. The exposures of cases and controls were compared by a Wilcoxon rank sum test. Odds ratios and dose-response relationships were studied by logistic regression.

RESULTS

Whether assessed as the extent during the workday or days/week, most physical exposures, in particular upper limb posture and repetition, were significant risk indicators with clear dose-response relationships. These findings were supported by psychophysical responses that also identified perceived work pace and the use of force as risk indicators. The identified psychosocial relations were limited to measures reflecting physical exposures.

CONCLUSIONS

While the identified risk indicators have previously been associated to upper limb symptoms as well as to diagnosed disorders other than brachial plexopathy, this study indicates an association between physical and work-exposures and brachial plexopathy. Longitudinal studies should be conducted in order to exclude bias from information and selection, both of which may occur with the applied case-control design.

Work with prolonged arm elevation as a risk factor for shoulder pain: a longitudinal study among young adults

This prospective study aimed at examining if work with prolonged arm elevation predicts shoulder pain among 41 young adults in their first years of working life. Fifteen hairdressers, 15 electricians, 5 students and 6 with various work were followed over a 2.5-year period (2006/7-2009). Arm elevation was measured with inclinometers during a full working day at baseline. Shoulder pain was reported at baseline and twice in the follow-up period. Data were analyzed by generalized estimating equations (GEE-analysis), stratified by gender and adjusted for time, mechanical workload, work demand, physical activity, tobacco use and prior shoulder pain. Work with prolonged arm elevation with angles >60° and >90° were associated with shoulder pain among women. Even though the shoulder pain levels are low the study suggests work with arms elevated as an early work-related risk factor among women, and indicates the importance of early prevention strategies.

National survey of back & neck pain amongst consultant ophthalmologists in the United Kingdom

Repetitive tasks, awkward or prolonged working postures, and high cognitive load are risk factors for occupational musculoskeletal disorders. Ophthalmologists may be vulnerable given that they are exposed to a combination of these factors. This national study assesses the prevalence, severity and associations of back and neck pain amongst UK consultant ophthalmologists. A postal survey was conducted using addresses supplied by the Royal College of Ophthalmologists. Statistical analysis was performed using Pearson correlation coefficient, two-tailed probability testing, analysis of variance (ANOVA) and Dunn's multiple comparison test. 518 responses were received (50.3 % response rate). Back and neck pain were reported by 50.6 % (262/518) and 31.8 % (165/518) of respondents, respectively, with 62.4 % (323/518) reporting one or both. 33.6 % (174/518) reported pain whilst operating, of whom 78.7 % (137/174) found operating exacerbated their pain. 31.7 % (164/518) reported pain when using the slit lamp, of whom 71.3 % (117/164) found it exacerbated their pain. Individual subspecialties showed a significant relative risk of back or neck pain in some circumstances, when compared to ophthalmologists as a whole. Occupational back and neck pain remains a problem amongst ophthalmologists. Recommendations are made for modifications to the working environment, and consideration should be given to improving education for trainees.

Mechanical stress

This chapter discusses mechanical stressors that are believed to be associated with work-related musculoskeletal disorders. It starts with an introduction to work-related musculoskeletal disorders (particularly those with high incidences in workplaces, such as disorders of low back, neck/shoulder, hand/wrist, elbow, and knee) in high-risk industries, and those mechanical stressors (such as high forces, awkward postures, high repetitions, excessive contact stress, and harmful human vibrations) in workplaces that are responsible for these disorders. Quantification methods of these mechanical stressors are then discussed. Although various quantification methods such as self-report, observational technique, and direct measurement are discussed, details are focused on many of those well-published observational techniques used by practitioners to assess risk levels of these mechanical stressors in jobs. These methods can quantify job mechanical stressors and provide risk level indications that can be used by practitioners to facilitate their decision making. These methods can also be used to evaluate the improvements of ergonomics interventions by comparing the risk levels quantitatively before and after the interventions.

Comparative study of upper limb load assessment and occurrence of musculoskeletal disorders at repetitive task workstations

This study explored the relationship between subjectively assessed complaints of pain in the arm, forearm and hand, and musculoskeletal load caused by repetitive tasks. Workers (n=942) were divided into 22 subgroups, according to the type of their workstations. They answered questions on perceived musculoskeletal pain of upper limbs. Basic and aggregate indices from a questionnaire on the prevalence, intensity and frequency of pain were compared with an upper limb load indicator (repetitive task index, RTI) calculated with the recently developed Upper Limb Risk Assessment (ULRA). There was relatively strong correlation of RTI and general intensity and frequency of pain in the arm, and general intensity and frequency of pain in the arm and forearm or prevalence of pain in the arm. Frequency and intensity of pain in the arm were weakly correlated. An aggregate indicator of evaluation of MSDs, which was calculated on the basis of the prevalence, intensity and frequency of pain, was to a higher degree associated with the musculoskeletal load of a task than basic evaluative parameters. Thus, such an aggregate indicator can be an alternative in comparing subjectively assessed MSDs with task-related musculoskeletal load and in establishing limit levels for that load.

Neck and shoulder muscle activity during standardized work-related postural tasks

The aim of the present study was to assess the activity levels of the sternocleidomastoid muscle and upper trapezius muscle during static postures under controlled and standardized conditions, and to determine whether the muscle activity differed between sexes. Electromyographic (EMG) activity was recorded unilaterally from the sternocleidomastoid and upper trapezius muscle in 17 participants whilst they were performing various postural tasks. EMG amplitude was measured by the root mean square values of the raw signals and normalized to peak maximum contractile values for each muscle (%MVC). The intensity of muscle activity was ranked as light (<3%MVC), moderate (3%MVC ≤ EMG ≤ 8%MVC), and substantial (>8%MVC). During most tasks the two muscles contracted light to moderately. Head leaning and shoulder shrugging postures yielded substantial muscle activity in both muscles. Muscle activity did not differ significantly between male and female participants (F = 3.1; p = 0.078). Our findings provided normative values, which will enhance future studies of muscle activity during work in a natural, unrestrained environment.

Strengths and limitations of a musculoskeletal model for an analysis of simulated meat cutting tasks

This study assessed the capacity of a musculoskeletal model to predict the relative muscle activation changes as a function of the workbench height and the movement direction during a simulated meat cutting task. Seven subjects performed a cutting task alternating two cutting directions for 20 s at four different workbench heights. Kinematics, electromyography (EMG), and cutting force data were collected and used to drive a musculoskeletal model of the shoulder girdle. The model predicted the muscle forces exerted during the task. Both the recorded and computed activation of the muscles was then compared by means of cross-correlation and by comparison of muscle activation trends with respect to the workstation parameters, i.e. cutting direction and workbench height. The results indicated that cutting movements involving arm flexion are preferable to movement requiring internal arm rotation and abduction. The optimal bench height for meat cutting tasks should be between 20 and 30 cm below the worker's elbow height. The present study underlines a beneficial use of musculoskeletal models for adjusting workstation parameters.

Musculoskeletal disorders and occupational exposures: How should we judge the evidence concerning the causal association?

Musculoskeletal disorders (MSDs) affecting the back, upper and lower extremities are widespread in the general population, implying a variety of causal factors. Multiple causes are not mutually exclusive, and a high background rate does not preclude associations with specific factors that are uncommon in the general population. MSDs have well-documented associations with occupational ergonomic stressors such as repetitive motion, heavy lifting, non-neutral postures, and vibration. Organizational features of the work environment, such as time pressure and low decision latitude, may also play a role, at least by potentiating the effects of physical loading. Numerous systematic reviews have mostly concurred with these overall findings. Nevertheless, some continue to debate whether MSDs are sometimes work-related, even for those performing jobs with repetitive and routinized tasks, heavy lifting, and/or pronounced postural strain. This article discusses (1) some epidemiologic features of MSDs that underlie that debate; and (2) the question of what should appropriately be considered a gold standard for scientific evidence on an etiological question such as the health effects of a non-voluntary exposure, such as an occupational or environmental agent. In particular, randomized clinical trials have little relevance for determining the health effects of non-therapeutic risk factors.

Work, health, and welfare: the association between working conditions, welfare states, and self-reported general health in Europe

This article is the first to examine the association between self-reported general health and a wide range of working conditions at the European level and by type of welfare state regime. Data for 21,705 men and women ages 16 to 60 from 27 European countries were obtained from the 2010 European Working Conditions Survey. The influence of individual-level sociodemographic, physical, and psychosocial working conditions and of the organization of work were assessed in multilevel logistic regression analyses, with additional stratification by welfare state regime type (Anglo-Saxon, Bismarckian, Eastern European, Scandinavian, and Southern). At the European level, we found that "not good" general health was more likely to be reported by workers more exposed to hazardous working conditions. Most notably, tiring working positions, job strain, and temporary job contracts were strongly associated with a higher likelihood of reporting "not good" health. Analysis by welfare state regime found that only tiring or painful working conditions were consistently associated with worse self-reported health in all regimes. There was no evidence that the Scandinavian welfare regime protected against the adverse health effects of poor working conditions. The article concludes by examining the implications for comparative occupational health research.

Herniation of the cervical disk in plastic surgeons

Herniations of the cervical disk in plastic surgeons are far more common in practice than the paucity of reported cases would indicate. A likely explanation may be the peculiar, nonergonomic positions that plastic surgeons must hold during surgery while wearing a headlight and loupes. From January 2003 to December 2006, at Tri-Service General Hospital, Taiwan, 4 plastic surgeons experienced herniations of the cervical disk. Magnetic resonance imaging study indicated there was disk herniation or bulging with spinal cord impingement. Two plastic surgeons received cervical diskectomy, corpectomy with strut reconstruction using titanium cages. These 2 surgeons were symptom-free 2 years after their operations. The other 2 plastic surgeons were under conservative physical therapy with persistent symptoms. The clinical evidence indicated that cervical disk herniation is an occupational hazard in plastic surgeons. To prevent prolonged hyperflexion and twisting of the neck, we proposed wearing a cervical brace during surgery for the plastic surgeons at Tri-Service-General Hospital since January 2008. No more plastic surgeons have experienced herniation of the cervical disk since then. The results indicated that wearing a cervical brace may be an effective measure to protect plastic surgeons from cervical disk disease.

Exposure-response relationships in work-related musculoskeletal disorders in elbows and hands - A synthesis of group-level data on exposure and response obtained using uniform methods of data collection

There is a serious lack of quantitative data regarding exposure-response relationships between occupational risk factors and musculoskeletal elbow and hand disorders. This paper explores such relationships in group-level data from our earlier cross-sectional studies. Prevalence of complaints (Nordic Questionnaire) and diagnoses (physical examination) were recorded in 19 groups of female workers (1891 individuals), and 8 groups of male workers (761 individuals), with highly similar work tasks within each group. Linear regression was performed on the group means of wrist postures and angular velocity (obtained by electrogoniometers), as well as muscular load (obtained using electromyography), recorded in representative sub-samples, and psychosocial exposure (Job Content Questionnaire). To tackle within-group variations in physical exposure, sensitivity analyses were performed by bootstrapping simulations, rendering confidence intervals. The sex-adjusted slope of the regression line (β) for wrist angular velocity vs. complaints during the past 7 days was 0.6%/(°/s), (95% CI 0.3-0.9), and for carpal tunnel syndrome (CTS) 0.2%/(°/s), (0.1-0.3). For palmar flexion, p50, β over the past 7 days was 0.8%/° (0.4-1.2); for CTS 0.3%/° (0.1-0.5); β for muscular activity p90: 0.9%/%MVE (0.3-1.6), and 0.3%/%MVE (-0.03-0.6) respectively and finally β for muscular rest: -1.2%/%time (-2.4-0.03) and -0.5%/%time (-0.9 to -0.01). Relationships were also demonstrated for low job control, job strain and isostrain. Women exhibited a higher prevalence of complaints than men. In conclusion, we have established quantitative exposure-response relationships between physical work load and elbow/hand disorders. Wrist angular velocity was the most consistent risk factor.

Rationalisation in public dental care--impact on clinical work tasks and mechanical exposure for dentists--a prospective study

Swedish dentistry has been exposed to frequent rationalisation initiatives during the last half century. Previous research has shown that rationalisation often results in increased risk of developing work-related musculoskeletal disorders, thus reducing sustainability in the production system. In this prospective study, we assessed mechanical exposures among Swedish dentists in relation to specific rationalisations of clinical dental work during a six-year period. Body postures and movements of 12 dentists were assessed by inclinometry synchronised to video recordings of their work. No rationalisation effects could be shown in terms of a reduction in non-value-adding work ('waste'), and at job level, no major differences in mechanical exposure could be shown between baseline and follow-up.

CONCLUSION

The present rationalisation measures in dentistry do not seem to result in rationalisation at job level, but may potentially be more successful at the overall dental system level.

PRACTITIONER SUMMARY

In contrast to many previous investigations of the mechanical exposure implications of rationalisation, the present rationalisation measures did not increase the level of risk for dentists. It is highlighted that all occupations involved in the production system should be investigated to assess production system sustainability.

Wrist activity monitor counts are correlated with dynamic but not static assessments of arm elevation exposure made with a triaxial accelerometer

There is evidence in the literature of a link between workplace arm elevation exposure and atraumatic shoulder injuries. However, there are several methods that can be used to assess this exposure. The goal of the present study was to compare the outcomes of an activity monitor attached to the wrist and a triaxial accelerometer mounted on the humerus. Twenty-one workers wore both sensors over the course of a full workday. While the activity monitor data was not significantly correlated with any static humeral parameters, it was strongly correlated with all dynamic parameters. The use of a simple, commercially available activity monitor might offer an inexpensive alternative for the assessment of a large number of subjects over multiple workdays to determine the relationship between dynamic motion and occupation shoulder injuries in the future.

PRACTITIONER SUMMARY

Arm overuse has been linked to occupation-related shoulder injuries. An activity monitor attached to the wrist and a triaxial accelerometer mounted on the humerus were compared in a field trial. The results demonstrate that, under certain conditions, a commercially available activity monitor might be a useful tool for exposure assessment.

Prevalence of neck pain and associated factors with personal characteristics, physical workloads and psychosocial among male rubber workers in FELDA settlement Malaysia

Rubber tapping processes posed potential risk of various health problems among rubber workers. It ranges from simple musculoskeletal aches to more serious and complicated structural damage to bone, muscles, tendons and nerves of musculoskeletal system. These health problems might be linked directly to the arduous demands of farm labor.

Biomechanical effects of mobile computer location in a vehicle cab

OBJECTIVE

The objective of this research is to determine the best location to place a conventional mobile computer supported by a commercially available mount in a light truck cab.

BACKGROUND

U.S. and Canadian electric utility companies are in the process of integrating mobile computers into their fleet vehicle cabs. There are no publications on the effect of mobile computer location in a vehicle cab on biomechanical loading, performance, and subjective assessment.

METHOD

The authors tested four locations of mobile computers in a light truck cab in a laboratory study to determine how location affected muscle activity of the lower back and shoulders; joint angles of the shoulders, elbows, and wrist; user performance; and subjective assessment. A total of 22 participants were tested in this study.

RESULTS

Placing the mobile computer closer to the steering wheel reduced low back and shoulder muscle activity. Joint angles of the shoulders, elbows, and wrists were also closer to neutral angle. Biomechanical modeling revealed substantially less spinal compression and trunk muscle force. In general, there were no practical differences in performance between the locations. Subjective assessment indicated that users preferred the mobile computer to be as close as possible to the steering wheel.

CONCLUSION

Locating the mobile computer close to the steering wheel reduces risk of injuries, such as low back pain and shoulder tendonitis.

APPLICATION

Results from the study can guide electric utility companies in the installation of mobile computers into vehicle cabs. Results may also be generalized to other industries that use trucklike vehicles, such as construction.

Biofeedback effectiveness to reduce upper limb muscle activity during computer work is muscle specific and time pressure dependent

Continuous electromyographic (EMG) activity level is considered a risk factor in developing muscle disorders. EMG biofeedback is known to be useful in reducing EMG activity in working muscles during computer work. The purpose was to test the following hypotheses: (1) unilateral biofeedback from trapezius (TRA) can reduce bilateral TRA activity but not extensor digitorum communis (EDC) activity; (2) biofeedback from EDC can reduce activity in EDC but not in TRA; (3) biofeedback is more effective in no time constraint than in the time constraint working condition. Eleven healthy women performed computer work during two different working conditions (time constraint/no time constraint) while receiving biofeedback. Biofeedback was given from right TRA or EDC through two modes (visual/auditory) by the use of EMG or mechanomyography as biofeedback source. During control sessions (no biofeedback), EMG activity was (mean ± SD): 2.4 ± 1.1, 2.5 ± 2.1, and 9.1 ± 3.1%max-EMGrms for right and left TRA and EDC, respectively. During biofeedback from TRA, activity was reduced in right TRA (1.7 ± 1.6%max-EMGrms) and left TRA (1.2 ± 2.0%max-EMGrms) compared to control. During biofeedback from EDC, activity in EDC was reduced (8.3 ± 3.3%max-EMGrms) compared with control. During time constraint, activity was reduced in right TRA (1.9 ± 1.3%max-EMGrms), left TRA (1.5 ± 1.5%max-EMGrms), and EDC (8.4 ± 3.2%max-EMGrms), during biofeedback compared to control.

CONCLUSION

biofeedback reduced muscle activity in TRA by ∼ 30-50% and in EDC by ∼ 10% when given from the homologous or bilateral muscle but not from the remote muscle, and was significant in the time constraint condition; while feedback source and presentation mode showed only minor differences in the effect on reducing homologous muscle activity. This implies that biofeedback should be given from the most affected muscle in the occupational setting for targeting relief and prevention of muscle pain most effectively.

In vivo measurement of humeral elevation angles and exposure using a triaxial accelerometer

OBJECTIVE

The aim of this study was to measure the capability of a triaxial accelerometer (Virtual Corset) to collect humeral elevation angles and exposure parameters in a simulated occupational environment.

BACKGROUND

There is a need for an economical ambulatory device to estimate elevation angles and exposure parameters in occupational groups.

METHOD

A magnetic tracking device was used to assess the ability of the Virtual Corset to evaluate humeral elevation angles and identify exposure parameters with in vivo dynamic conditions for 16 female dental hygienists.

RESULTS

Significant differences were found for the reaching task with the Virtual Corset, underestimating the means of the average humeral elevation angle by 10 degrees and the means for the range of the humeral elevation by 4 degrees. Furthermore, significant differences were found for the exposure parameters with the Virtual Corset, overestimating the jerk by 4% and underestimating the percentage time above 40 degrees and 60 degrees by 9% and 4%, respectively. However, the Virtual Corset was able to identify similar kinematics patterns and exposure data when compared with a magnetic tracking device.

CONCLUSION

The outcomes of the study suggest that the Virtual Corset may be useful for data collection during a dental hygienist workday. Professions that have similar patterns of angular velocity and acceleration and humeral range of elevation as the dental hygienist flossing technique may benefit from the use of the Virtual Corset.

APPLICATION

This study provides evidence that the Virtual Corset can be used to reconstruct humeral elevation angles and identify exposure parameters in some tasks of dental hygienists.

The reliability of side to side measurements of upper extremity activity levels in healthy subjects

Background

In both clinical and occupational settings, ambulatory sensors are becoming common for assessing all day measurements of arm motion. In order for the motion of a healthy, contralateral side to be used as a control for the involved side, the inherent side to side differences in arm usage must be minimal. The goal of the present study was to determine the reliability of side to side measurements of upper extremity activity levels in healthy subjects.

Methods

Thirty two subjects with no upper extremity pathologies were studied. Each subject wore a triaxial accelerometer on both arms for three and a half hours. Motion was assessed using parameters previously reported in the literature. Side to side differences were compared with the intraclass correlation coefficient, standard error of the mean, minimal detectable change scores and a projected sample size analysis.

Results

The variables were ranked based on their percentage of minimal detectable change scores and sample sizes needed for paired t-tests. The order of these rankings was found to be identical and the top ranked parameters were activity counts per hour (MDC% = 9.5, n = 5), jerk time (MDC% = 15.8, n = 8) and percent time above 30 degrees (MDC% = 34.7, n = 9).

Conclusions

In general, the mean activity levels during daily activities were very similar between dominant and non-dominant arms. Specifically, activity counts per hour, jerk time, and percent time above 30 degrees were found to be the variables most likely to reveal significant difference or changes in both individuals and groups of subjects. The use of ambulatory measurements of upper extremity activity has very broad uses for occupational assessments, musculoskeletal injuries of the shoulder, elbow, wrist and hand as well as neurological pathologies.

The ability of limited exposure sampling to detect effects of interventions that reduce the occurrence of pronounced trunk inclination

Ergonomics interventions often focus on reducing exposure in those parts of the job having the highest exposure levels, while leaving other parts unattended. A successful intervention will thus change the form of the job exposure distribution. This disqualifies standard methods for assessing the ability of various exposure measurement strategies to correctly detect an intervention's effect on the overall job exposure of an individual worker, in particular for the safety or ergonomics practitioner who with limited resources can only collect a few measurements. This study used a non-parametric simulation procedure to evaluate the relationship between the number of measurements collected during a self-paced manufacturing job undergoing ergonomics interventions of varying effectiveness, and the probability of correctly determining whether and to which extent the interventions reduced the overall occurrence of pronounced trunk inclination, defined as an inclination of at least 20 degrees . Sixteen video-recordings taken at random times on multiple days for each of three workers were used to estimate the time distribution of each worker's exposure to pronounced trunk inclination. Nine hypothetical ergonomics intervention scenarios were simulated, in which the occurrence of pronounced trunk inclination in the upper 1/8, 1/4, and 1/2 of the job exposure distribution was reduced by 10%, 30% and 50%. Ten exposure measurement strategies were explored, collecting from one to ten pre- and post-intervention exposure samples from an individual worker. For each worker, intervention scenario and sampling strategy, data were bootstrapped from the measured (pre-intervention) and simulated (post-intervention) exposure distributions to generate empirical distributions of the estimated intervention effect. Results showed that for the one to three intervention scenarios that had the greatest effect on the overall occurrence of trunk inclination in the job, one to four pre- and post-intervention measurements, depending on worker, were sufficient to reach an 80% probability of detecting that the intervention did, indeed, have an effect. However, even for the intervention scenario that had the greatest effect on job exposure, seven or more samples were needed for two of the three workers to obtain a probability larger than 50% of estimating the magnitude of the intervention effect to within +/-50% of its true size. For almost all interventions affecting 1/8 or 1/4 of the job, limited exposure sampling led to low probabilities of detecting any intervention effect, let alone its correct size.

Gender differences, work stressors and musculoskeletal disorders in weaving industries

A study was undertaken to identify the work stressors among male and female weavers (N=516) in powerloom and handloom and examine the association of work stressors with the prevalence of work related musculo-skeletal disorders (MSDs). Physical and psychosocial stresses of work, job diagnostics, hazards of workplace, working environment and MSDs prevalence were assessed. There is high prevalence of MSDs among weavers. Female weavers in powerloom and handloom were more prone to developing MSDs in upper back (OR 1.8; p<0.05 and OR 2.1; p<0.01) and lower back (OR 1.9; p<0.05 and OR 1.8; p<0.05). Male weavers were more prone to developing pain in the knee (OR 2.9; p<0.001), and hand (OR 2.2; p<0.05). Multivariate analysis indicated that job duration >10 yr (OR 3.7, p<0.05), manual material handling (OR 3, p<0.05), and poor machinery safety (OR 11, p<0.05), contributed to occurrence of MSDs amongst powerloom weavers. Among the handloom weavers, age >25 yr (OR 3.2, p<0.05), poor machinery design (OR 2.2, p<0.01), mental overload (OR 5.7, p<0.001), skill requirement to perform jobs (OR 20.7, p<0.05) had significant influence in the occurrence of pain. Gender differences exist in the prevalence of MSDs and the perception of work and psycho-social stresses among the weavers.

Risk of musculoskeletal disorders among females and males in repetitive/constrained work

This paper combines epidemiological data on musculoskeletal morbidity in 40 female and 15 male occupational groups (questionnaire data 3720 females, 1241 males, physical examination data 1762 females, 915 males) in order to calculate risk for neck and upper limb disorders in repetitive/constrained vs. varied/mobile work and further to compare prevalence among office, industrial and non-office/non-industrial settings, as well as among jobs within these. Further, the paper aims to compare the risk of musculoskeletal disorders from repetitive/constrained work between females and males. Prevalence ratios (PR) for repetitive/constrained vs. varied/mobile work were in neck/shoulders: 12-month complaints females 1.2, males 1.1, diagnoses at the physical examination 2.3 and 2.3. In elbows/hands PRs for complaints were 1.7 and 1.6, for diagnoses 3.0 and 3.4. Tension neck syndrome, cervicalgia, shoulder tendonitis, acromioclavicular syndrome, medial epicondylitis and carpal tunnel syndrome showed PRs > 2. In neck/shoulders PRs were similar across office, industrial and non-office/non-industrial settings, in elbows/hands, especially among males, somewhat higher in industrial work. There was a heterogeneity within the different settings (estimated by bootstrapping), indicating higher PRs for some groups. As in most studies, musculoskeletal disorders were more prevalent among females than among males. Interestingly, though, the PRs for repetitive/constrained work vs. varied/mobile were for most measures approximately the same for both genders. In conclusion, repetitive/constrained work showed elevated risks when compared to varied/mobile work in all settings. Females and males showed similar risk elevations. This article enables comparison of risk of musculoskeletal disorders among many different occupations in industrial, office and other settings, when using standardised case definitions. It confirms that repetitive/constrained work is harmful not only in industrial but also in office and non-office/non-industrial settings. The reported data can be used for comparison with future studies.

Height of industrial hand wheel valves affects torque exertion

OBJECTIVE

The aim of this study was to determine how height of a hand wheel affects maximum torque production and risk of injury to the shoulders and back of workers.

BACKGROUND

Workers in the processing, refinery, and energy generation industries manually open and close valves with hand wheels that require high torque. This task is physically strenuous and can lead to shoulder musculoskeletal disorders (MSDs).

METHOD

Maximum torque exertions in the clockwise and counterclockwise directions at three heights (knee, chest, and overhead) were tested.

RESULTS

The torque production in the counterclockwise (left) direction was greater than that of the clockwise (right) direction (150.5 N.m vs. 141 N.m). This main effect was independent of valve height, as there was no interaction between direction and valve height (p = .686). Participants exerted at least 10% greater torque at the overhead level than at the chest level (means of 153.2 N.m vs. 138.3 N.m). There was no difference in maximum torque between knee and overhead levels and between knee and chest levels.

CONCLUSION

According to ergonomics principles, the risk of MSDs affecting the shoulder and trunk from turning valves should be lowest at chest height because the postures of the shoulder and trunk are at or near neutral. However, workers exerted greatest torque when the valve was located overhead. Whether valves located at overhead height, compared with chest height, present greater risk of MSDs to workers is not known.

APPLICATION

Design engineers should avoid placing hand wheel valves at knee height or lower.

The development of the Quick Exposure Check (QEC) for assessing exposure to risk factors for work-related musculoskeletal disorders

This paper describes the development and evaluation of the Quick Exposure Check (QEC), which is an observational tool developed for Occupational Safety and Health (OSH) practitioners to assess exposure to risks for work-related musculoskeletal disorders and provide a basis for ergonomic interventions. The tool is based on epidemiological evidence and investigations of OSH practitioners' aptitudes for undertaking assessments. It has been tested, modified and validated using simulated and workplace tasks, in two phases of development, with participation of 206 practitioners. The QEC allows the four main body areas to be assessed and involves practitioners and workers in the assessment. Trials have determined its usability, intra- and inter-observer reliability, and validity which show it is applicable to a wide range of working activities. The tool focuses primarily on physical workplace factors, but also includes the evaluation of psychosocial factors. Tasks can normally be assessed within 10min. It has a scoring system, and exposure levels have been proposed to guide priorities for intervention. Subsequently it should be used to evaluate the effectiveness of any interventions made. The QEC can contribute to a holistic assessment of all the elements of a work system.

Effect of head-mounted displays on posture

OBJECTIVE

The aim of the present study was to determine if a wearable system based on a head-mounted display (HMD) causes users to alter their head position and adopt postures that place greater stress on the musculoskeletal system.

BACKGROUND

HMDs are common output devices used with wearable computers. HMDs provide the wearer with visual information by projecting computer-generated virtual images in front of the eyes. Deviations of neck posture from a neutral upright position increase the stresses on the musculoskeletal system of the head and neck.

METHOD

Seven paramedics simulated the treatment of a patient under a normal condition and when using an HMD wearable computer system. During the simulations a posture analysis was performed using the Rapid Upper Limb Assessment method.

RESULTS

The postures adopted when wearing an HMD, as compared with a normal condition, scored significantly higher for the neck (z = 2.463, p < .05) and for overall body posture (left side of the body: z = 2.447, p < .05; right side of the body: z = 2.895, p < .05).

CONCLUSION

Wearing an HMD can force the wearers to modify their neck posture. As such, the musculoskeletal system of the head and neck may be placed under increased levels of stress.

APPLICATION

Potential users should be made aware that HMDs could dictate modifications in neck posture, which may have detrimental effects and may compound the weight effect of the HMD.