Results from a pooled data study of carpal tunnel syndrome
Objectives: This paper aimed to quantify exposure–response relationships between the American Conference of Governmental Industrial Hygienists' (ACGIH) threshold limit value (TLV) for hand-activity level (HAL) and incidence of carpal tunnel syndrome (CTS).
Methods: Manufacturing and service workers previously studied by six research institutions had their data combined and re-analyzed. CTS cases were defined by symptoms and abnormal nerve conduction. Hazard ratios (HR) were calculated using proportional hazards regression after adjusting for age, gender, body mass index, and CTS predisposing conditions.
Results: The longitudinal study comprised 2751 incident-eligible workers, followed prospectively for up to 6.4 years and contributing 6243 person-years of data. Associations were found between CTS and TLV for HAL both as a continuous variable [HR 1.32 per unit, 95% confidence interval (95% CI) 1.11–1.57] and when categorized using the ACGIH action limit (AL) and TLV. Those between the AL and TLV and above the TLV had HR of 1.7 (95% CI 1.2–2.5) and 1.5 (95% CI 1.0–2.1), respectively. As independent variables (in the same adjusted model) the HR for peak force (PF) and HAL were 1.14 per unit (95% CI 1.05–1.25), and 1.04 per unit (95% CI 0.93–1.15), respectively.
Conclusion: Those with exposures above the AL were at increased risk of CTS, but there was no further increase in risk for workers above the TLV. This suggests that the current AL may not be sufficiently protective of workers. Combinations of PF and HAL are useful for predicting risk of CTS.
Source: Kapellusch JM, Gerr FE, Malloy EJ, Garg A, Harris-Adamson C, Bao SS, Burt SE, Dale AM, Ellen E, Evanoff BA, Hegmann KT, Silverstein BA, Theise MS, Rempel DR. Scand J Work Environ Health, 2014.
Objective: To investigate a biopsychosocial model of risk for carpal tunnel syndrome (CTS). In addition, a host of exploratory psychosocial variables was investigated as potential risk factors for CTS.
Methods: A case–control design was used comparing 87 CTS and 74 sex-matched general orthopedic patients from an outpatient orthopedic clinic. All participants underwent the same diagnostic protocol (ie, physical evaluation and electrodiagnostic testing) and completed a self-report questionnaire assessing a wide range of potential occupational, personological, and psychosocial risk factors.
Results: Multiple logistic regression analyses revealed that occupational repetition, not engaging in vigorous exercise, physical activities with wrist strain, poorer physical health, and lower job satisfaction were significantly related to the presence of CTS. Obesity was borderline significantly related to the presence of CTS.
Conclusions: The biopsychosocial model provides a useful heuristic for conceptualizing CTS risk among injured workers.
Source: Goodson, Jason T.; DeBerard, M. Scott; Wheeler, Anthony J.; Colledge, Alan L. Journal of Occupational & Environmental Medicine: September 2014, Volume 56, Issue 9, p 965–972.
CBRG QuickDecks are now available from the Cochrane Back Review Group (CBRG), housed at the Institute for Work & Health. These slide decks provide a quick summary of the best evidence for treating back and neck pain by type of intervention, including surgical, pharmacological and non-pharmacological (e.g. massage, chiropractic) interventions.
Results From the Backworks Prospective Cohort Study
Objective: To evaluate relationships between lifting and lowering of loads and risk of low back pain resulting in medication use (M-LBP).
Methods: At baseline, worker demographics, psychosocial factors, hobbies, LBP history, and lifting and lowering (quantified using the Revised NIOSH Lifting Equation) were assessed. A cohort of 258 incident-eligible workers was followed up for 4.5 years to determine new M-LBP cases and changes in lifting/lowering requirements. Proportional hazards regression with time-varying covariates was used to model associations.
Results: Factors predicting M-LBP included peak lifting index (PLI) and composite lifting index (PCLI), LBP history, anxiety, and housework. In adjusted models, PLI and PCLI showed exposure–response relationships with peak hazard ratios of 3.8 and 4.3, respectively (P ≤ 0.02).
Conclusions: Lifting of loads is associated with increased risk of M-LBP. The PLI and PCLI are useful metrics for estimating the risk of M-LBP from lifting.
Source: Kapellusch, Jay M.; Garg, Arun; Boda, Sruthi; Hegmann, Kurt T.; Moore, J. Steven; Thiese, Matthew S.; Merryweather, Andrew; Tomich, Suzanna; Foster, James C.; Bloswick, Donald; Malloy, Elizabeth J. Journal of Occupational & Environmental Medicine: August 2014, Volume 56, Issue 8, p. 867–877.
Objective: We evaluated post-offer pre-placement (POPP) nerve conduction studies (NCS) for carpal tunnel syndrome (CTS), testing diagnostic yield and cost-effectiveness.
Methods: A total of 1027 newly hired workers underwent baseline NCS and were followed for an average of 3.7 years for diagnosed CTS. Measures of diagnostic yield included sensitivity, specificity, and positive predictive value (PPV). Cost-effectiveness of POPP screening was evaluated using a range of inputs.
Results: Abnormal NCS was strongly associated with future CTS with univariate hazard ratios ranging from 2.95 to 11.25, depending on test parameters used. Nevertheless, PPV was poor, 6.4% to 18.5%. Cost-effectiveness of POPP varied with CTS case costs, screening costs, and NCS thresholds.
Conclusions: Although abnormal NCS at hire increases risk of future CTS, the PPV is low, and POPP screening is not cost-effective to employers in most scenarios tested.
Source: Dale, Ann Marie; Gardner, Bethany T.; Zeringue, Angelique; Werner, Robert; Franzblau, Alfred; Evanoff, Bradley. Journal of Occupational & Environmental Medicine:
August 2014, Volume 56, Issue 8, p. 840–847.
This study of selected jobs in the health care sector explored a range of physical and psychosocial factors to identify those that most strongly predicted work-related musculoskeletal disorders (WMSD) risk. A self-report survey was used to collect data on physical and psychosocial risk factors from employees in three health care organisations in Victoria, Australia. Multivariate analyses demonstrated the importance of both psychosocial and physical hazards in predicting WMSD risk and provides evidence for risk management of WMSDs to incorporate a more comprehensive and integrated approach. Use of a risk management toolkit is recommended to address WMSD risk in the workplace.
Source: Oakman, Jodi, Macdonald, Wendy, Wells, Yvonne. (2014). Applied Ergonomics.
Review of Current Practice and Recommendations for Improvement
This document is a joint effort between NIOSH and the Canadian Centre of Research Expertise for the Prevention of Musculoskeletal Disorders (CRE-MSD).
The purpose of this document is to help practitioners assess working posture for the prevention and control of occupational musculoskeletal disorders (MSDs). Quantitative or semiquantitative descriptions of posture are inputs to many job analysis tools applied in MSD prevention and control. Studies of the relationship between risk factors (such as posture, repetition, and force) and resulting MSD prevalence have used various approaches to characterizing working posture, including observation-based methods. Posture classification by systematic observation of a worker is commonly used in research and by practitioners, such as ergonomists, industrial hygienists, and safety professionals, to help inform job design decisions and establish safe work limits to reduce MSD injury risk in the workplace.
A systematic review of observational studies
Systematically review observational studies concerning the question whether workers that perform pushing/pulling activities have an increased risk for upper extremity symptoms as compared to workers that perform no pushing/pulling activities. A search in MEDLINE via PubMed and EMBASE was performed with work-related search terms combined with push/pushing/pull/pulling. Studies had to examine exposure to pushing/pulling in relation to upper extremity symptoms. Two authors performed the literature selection and assessment of the risk of bias in the studies independently. A best evidence synthesis was used to draw conclusions in terms of strong, moderate or conflicting/insufficient evidence. The search resulted in 4764 studies. Seven studies were included, with three of them of low risk of bias, in total including 8279 participants. A positive significant relationship with upper extremity symptoms was observed in all four prospective cohort studies with effect sizes varying between 1.5 and 4.9. Two out of the three remaining studies also reported a positive association with upper extremity symptoms. In addition, significant positive associations with neck/shoulder symptoms were found in two prospective cohort studies with effect sizes of 1.5 and 1.6, and with shoulder symptoms in one of two cross-sectional studies with an effect size of 2.1. There is strong evidence that pushing/pulling is related to upper extremity symptoms, specifically for shoulder symptoms. There is insufficient or conflicting evidence that pushing/pulling is related to (combinations of) upper arm, elbow, forearm, wrist or hand symptoms.
Source: Hoozemans, Marco J.M., Knelange, E.B., Frings-Dresen, M.H.W., Veeger, H.E.J., et Kuijer, P.P.F.M. (2014). Occupational & Environmental Medicine.
Past efforts have been made to design single-user workstations to accommodate users' anthropometric and preference distributions. However, there is a lack of methods for designing workstations for group interaction. This paper introduces a method for sizing workstations to allow for a personal work area for each user and a shared space for adjacent users. We first create a virtual population with the same anthropometric and preference distributions as an intended demographic of college-aged students. Members of the virtual population are randomly paired to test if their extended reaches overlap but their normal reaches do not. This process is repeated in a Monte Carlo simulation to estimate the total percentage of groups in the population that will be accommodated for a workstation size. We apply our method to two test cases: in the first, we size polygonal workstations for two populations and, in the second, we dimension circular workstations for different group sizes.
Source: Mahoney, Joseph M., Kurczewski, Nicolas A., et Froede, Erick W. (2014). Applied Ergonomics.
Le Programme de prévention des TMS liés au travail du Réseau de santé publique en santé au travail (RSPSAT) a été mis en place en avril 2008, suite à la publication d'un document de réflexion sur le rôle de la santé publique en prévention des TMS liés au travail et de proposition des orientations de la Table de concertation nationale en santé au travail (TCNSAT) et de l'Institut national de santé publique du Québec (INSPQ) (Stock et coll., 2005). Ce programme vise l'identification de la présence de TMS liés au travail et des facteurs de risque professionnels associés aux TMS et l'intégration des risques TMS aux programmes de santé spécifiques aux entreprises (PSSE), au même titre que les autres risques à la santé au travail. Il vise également la mobilisation des entreprises ayant des facteurs de risque de TMS importants à s'engager dans des activités de prévention. Un programme à quatre blocs a été proposé. Les membres de la TCNSAT ont décidé de lancer le Programme Réseau de prévention des TMS par étape à travers la province. Ils favorisaient d'abord l'implantation des deux premiers blocs du Programme, en tant qu'offre de service minimal aux établissements concernés lors de l'élaboration ou la mise à jour des PSSE.
OBJECTIVES: Epidemiological studies have shown that musculoskeletal symptoms are frequent occupational injury and disability among nurses in developing countries. Preventive measures were not able to reduce musculoskeletal disorders significantly in nursing profession. This study was performed to provide a comprehensive assessment of the association among risk factors in developing musculoskeletal symptoms.
METHOD: A structural equation model was applied to describe and analyse complex causal relationships from sets of occupational variables involved in musculoskeletal symptoms. A questionnaire was applied to nurses at hospitals affiliated to Semnan Medical Sciences University to collect data on personal and occupational factors and musculoskeletal symptoms. An ergonomic rapid entire body assessment measured work posture risks.
RESULTS: Physical work demand and mental pressure increased the risk of musculoskeletal disorders significantly. Musculoskeletal symptoms increased in nurses who worked for extended hours and experienced frequent unstable work posture. Structural equation model showed that musculoskeletal symptoms were associated directly and indirectly by physical and mental job variables, employment status, age and lifestyle.
CONCLUSIONS: Covarience structural analysis is useful to describe and understand both the direct and indirect effects of variables with complex relationship between risk factors on the prediction of musculoskeletal symptoms.
Source: Dehdashti A. Occup. Environ. Med. 2014; 71(Suppl 1): A68-A68.
This leaflet includes the Manual Handling Assessment Charts (MAC). MAC is a tool developed to help users identify high-risk workplace manual handling activities.
Employers and safety representatives can use the tool to assess the risks posed by lifting, carrying and team manual handling activities. It will help them understand, interpret and categorise the level of risk of the various known risk factors associated with manual handling activities. MAC has a numerical and colour coding score system to highlight high-risk manual handling tasks.
Order picking can be defined as the retrieval of stock keeping units from a warehouse according to a pick list generated from a customer order prior to the despatch of the completed order to the customer.
There is a variety of order picking systems that are used in warehouses and distribution centres and the choice of system will determine the amount and type of manual handling that occurs within those locations. In order to understand the factors that influence the design of order picking systems a literature review was undertaken and telephone interviews were conducted with six industry stakeholders. The stakeholders included were two retailers with distribution networks operating across the UK, two specifiers who design order picking systems of different types and complexity for the end users, and two major suppliers of order picking systems.
The factors that influence the amount of manual handling within warehouses and distribution centres are complex and inter-locking. The key factor is the design of the order picking system, particularly how much automation is used and whether pickers travel between pick slots or whether items are automatically delivered to them. It also depends on the nature of the goods that the warehouse handles. There are financial trade-offs between high capital costs of automated systems, and increased labour costs in manual systems.
This work was commissioned to examine more closely the nature of the forces exerted during manual pushing and pulling operations and to provide a pushing and pulling risk assessment tool that aids identification of key workplace risk factors and measures for control of the risks that they present. It builds on the work reported in RR562 (HSE 2007).
Magnitude of exerted force is one of several factors that may precipitate injury to the musculoskeletal system during pushing and pulling operations, but the force demands in any pushing and pulling operation are not an independent aspect; they are a direct consequence of workplace factors that are present. Practical problems associated with workplace measurement of the task forces are encouraging risk assessment procedures that preclude measurement of the task forces. With input from groups of ergonomists, and potential users (regulatory inspectors and duty holders), it was possible to develop a prototype pushing and pulling operations assessment tool that is user-friendly, reduces/eliminates the need for measurement of force, requires minimal expert knowledge to apply, identifies high-risk operations and intuitively indicates good practice.
Further work in field trialling is now required with the potential users (regulatory inspectors and duty holders) to clarify its usability and effectiveness in real task situations.
De récentes revues de la littérature épidémiologique montrent que travailler avec les bras en position levée augmente la probabilité de développer des troubles musculosquelettiques (TMS) aux épaules. Bien que l’origine et les mécanismes de TMS à l’épaule manquent d’évidence dans la littérature scientifique, réaliser une tâche avec les bras en position levée cause un chargement de la musculature de l’épaule plus important. Cependant, peu d’éléments permettent d’expliquer les raisons pour lesquelles cette posture avec les bras élevés est gênante, et comment celle-ci affecte le membre supérieur en mouvement. La modélisation musculosquelettique du corps humain est aujourd’hui un moyen efficace et non invasif pour obtenir des informations sur les efforts internes qui sont appliqués aux muscles, aux tendons et aux os.
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