Physical limitations and musculoskeletal complaints associated with work in unusual or restricted postures: a literature review

INTRODUCTION: The vast majority of ergonomics research has addressed the demands of work in standing or sitting postures, and understandably so. However, many workers (e.g., underground miners, aircraft baggage handlers, plumbers, agricultural workers, mechanics, and others) are often required to adopt postures such as kneeling, stooping, squatting, or lying down for significant periods of the workday. METHOD: A literature search was performed using the ISI Web of Science database (for years 1980-2004). Articles retrieved from this search were evaluated in terms of relevance to assessing physical capabilities of workers in these postures and/or the musculoskeletal epidemiology associated with these postures. RESULTS: Work in unusual and restricted postures was associated with significantly higher rates of musculoskeletal complaints compared to workers not adopting these postures in epidemiology studies (Odds Ratios ranging from 1.13 to 13). Some studies suggested a dose-response relationship, with longer exposures leading to increased musculoskeletal complaints. Physical strength and psychophysical lifting capacity vary significantly as unusual or restricted postures are adopted, with lower lifting capacities evident in the kneeling, squatting, and lying positions. CONCLUSIONS: Workers who adopt unusual or restricted postures appear to be at higher risk of musculoskeletal complaints and often exhibit reduced strength and lifting capacity. Research needs in this area include improved exposure assessment tools, studies of intervention effectiveness, adaptations of the body in response of work in unusual postures, and elucidation of relevant injury pathways. IMPACT ON INDUSTRY: Workers who adopt unusual or restricted postures in their work often experience higher musculoskeletal injury rates. If awkward postures cannot be eliminated in the workplace, jobs should be designed in accordance with the reduced strength and lifting capabilities observed in these postures.     

An analysis of injury claims from low-seam coal mines

Introduction

The restricted workspace present in low-seam coal mines forces workers to adopt awkward working postures (kneeling and stooping), which place high physical demands on the knee and lower back.

Method

This article provides an analysis of injury claims for eight mining companies operating low-seam coal mines during calendar years 1996-2008. All cost data were normalized using data on the cost of medical care (MPI) as provided by the U.S. Bureau of Labor Statistics.

Results

Results of the analysis indicate that the knee was the body part that led in terms of claim cost ($4.2 million), followed by injuries to the lower back ($2.7 million). While the average cost per injury for these body parts was $13,100 and $14,400, respectively (close to the average cost of an injury overall), the high frequency of these injuries resulted in their pre-eminence in terms of cost. Analysis of data from individual mining companies suggest that knee and lower back injuries were a consistent problem across companies, as these injuries were each among the top five most costly part of body for seven out of eight companies studied.

Application/Impact

Results of this investigation suggest that efforts to reduce the frequency of knee and low back injuries in low-seam mines have the potential to create substantial cost savings.