Michael J. Jorgensen

Work-related musculoskeletal disorders (WMSDs) pose a substantial burden in nonrepetitive jobs such as construction. However, identifying the principal sources of ergonomic risk is challenging because of the wide scope of tasks that the assessor must analyse. Existing assessment methods in these workplaces are either cumbersome or rely on approximation. This study proposes a worker feedback elicitation mechanism to suggest a smaller scope for high-risk problem activities. The five-step template consists of short focus groups and surveys and is designed to be flexible, comprehensive, simple, and replicable. The template was deployed among 11 construction crews across five employers and validated along four quality dimensions: predictive validity, effectiveness, test-retest reliability, and intra-rater reliability. Workers were able to consistently identify activities with elevated ergonomic risk, but not necessarily in the same order as the control method, and were able to reduce the number of activities that merit further investigation by 60%.

Passive arm support exoskeletons (ASEs) have attracted interest with the prospect of reducing shoulder musculoskeletal injuries. The objective of this study was to assess the impact of passive ASEs on electrical activation of shoulder and torso muscles while performing simulated vertical and horizontal drilling exertions by 17 experienced aircraft workers. The tasks included three vertical drilling heights (chin, head, overhead levels) and two horizontal drilling heights (eye, overhead levels), where participants performed five two-second exertions with one-second no-exertion times between successive drilling exertions. Electromyographic signals from the anterior and medial deltoids, trapezius, latissimus dorsi, erector spinae, biceps and triceps were captured. During vertical drilling exertions, ASEs significantly reduced dominant and non-dominant medial deltoid muscle activity, as well as activity in the non-dominant anterior deltoid, but not the dominant anterior deltoid. During horizontal drilling exertions, ASEs significantly decreased dominant and non-dominant anterior and medial deltoid muscle activity. ASEs significantly reduced non-dominant and dominant anterior and medial deltoid muscle activity during the time between drilling exertions in both the vertical and horizontal drilling directions. These results are encouraging in suggesting that ASEs reduce muscular exertion during drilling tasks commonly found in aircraft manufacturing. However, ASEs must be evaluated in worksite studies to better assess their efficacy.

Objective: The aim of the study is to describe cost and frequency of work-related musculoskeletal disorders in Kansas. Methods: Data were provided by the Kansas Department of Labor and included all closed workers' compensation claims entailing indemnity and medical costs from 2014 to 2022. Results: Work-related musculoskeletal disorder claims entailed a median total cost of $20,097. Medical comprised 48.4% of costs, indemnity 46.4%, and legal 5.2%. The most frequently injured and costliest body part was the shoulder. Manufacturing comprised 28.4% of claims, followed by health care and office. Lifting was the most common cause, generating 32.0% of claims. Education, transportation, and mining were among industries with above average claim rates. Conclusions: Very few studies use workers' compensation data to assess work-related musculoskeletal disorder costs. This study introduces a state not yet analyzed and presents more recent years of data than available in the literature.

BACKGROUND: The American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs) for Lifting is a manual material handling (MMH) assessment method to identify weight limits that nearly all workers may be exposed to without developing work-related low back disorders (LBD). However, this assessment method only applies to lifting with the torso within 30° asymmetry of the sagittal plane. OBJECTIVE: Estimate TLV weight limits while lifting with torso asymmetry greater than 30° beyond the sagittal plane. METHODS: Lifting tasks were performed from various horizontal and vertical locations, at torso asymmetry angles of 0°, 15°, 30°, 45°, 60°, 75° and 90°, using ACGIH identified TLVs. Validated MMH assessment methods (NIOSH Lifting Equation, Ohio State University LBD Risk Model) were utilized to estimate TLVs at torso asymmetries greater than 30°. RESULTS: The current ACGIH TLVs resulted in low- to moderate-risk risk levels for torso asymmetries from 0° to 30°, and the risk incrementally increased as torso asymmetry increased to 90°. With the intention to keep the risk levels to that found at 30° torso asymmetry, lower TLV weight limits in the vertical and horizontal zones investigated were estimated for torso asymmetries from 45° to 90°. The resulting adjusted TLVs were consistent with weight limits identified for similar lifting conditions from other assessment methods that account for torso asymmetry. CONCLUSIONS: This research found current ACGIH-defined TLVs possess less than high-risk for LBD, and provided guidance to practitioners for reduced TLVs when torso asymmetry is greater than 30° from the sagittal plane.

Risk factors associated with the development of musculoskeletal discomfort and disorders during the operation of heavy mobile equipment include whole-body vibration and awkward and sustained joint postures of the shoulders, neck, and trunk. Cab design may influence awkward postures of the joints, and task duration may influence duration of exposure to awkward and static postures and whole-body vibration. To reduce exposure to risk factors related to the interface between cab design and task, it may be necessary for manufacturers to address cab design. This study assessed the repeatability of a cab design checklist developed to evaluate various design characteristics that can influence exposure to risk factors for musculoskeletal discomfort. The ability of the cab design checklist to identify posture-related deficiencies of design was also assessed. The checklist was used by two administrators across 10 pieces of heavy construction equipment. Video analysis was performed to quantify postures of the neck, shoulder, and trunk; correlation analysis was used to determine whether specific questions from the checklist were associated with the identification of awkward postures. The repeatability assessment resulted in kappa coefficients ranging from 0.52 to 1.0 (good-to-excellent reproducibility) across each piece of equipment, and an overall kappa coefficient of 0.77 (excellent reproducibility) when considering all equipment together. Results from the correlation analysis showed that shoulder flexion posture was correlated with scores from the cab design checklist. However, results of the cab design checklist were not significantly correlated with shoulder abduction or awkward postures of the neck and trunk. Results suggest that the cab design checklist may be useful for identifying cab design characteristics that need further improvement and for identifying design characteristics that increase shoulder flexion. The strength of the repeatability assessment suggests that outcomes of the cab design checklist administered by different individuals may be consistent, independent of the type of equipment being assessed.