Biomechanics of manual materials handling and low-back pain.
Occupational safety and health symposia 1977. Cincinnati, OH: U.S. Department of Health, Education, and Welfare, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHEW (NIOSH) Publication No. 78-169, 1978 Jun; :41-82
The biomechanical aspects of manual materials handling and low back pain were discussed. Biomechanical principles involved in manual materials handling were reviewed. Muscle forces required to hold an object in the hands and to lift a 20 kilopond (1 kilopond equals 1 kilogram of force) weight at arm's length were computed as examples of the mechanical stress associated with manual materials handling. The roles of compressive stresses induced by manual materials handling and lumbar disk degeneration in low back pain were considered. It was noted that harmful levels of mechanical stress can be experienced by the lower back of a person even when handling moderate loads. Safe lifting rules were discussed. The rules indicate that objects should be brought in as close to the body as possible before lifting them and hyperflexion of the back should be avoided. Data relating low back pain and manual materials handling were reviewed. These show that the percentage of compensable medical claims originating from low back pain range from approximately 15 percent for all United States (US) industries to 30 percent for certain industries in Sweden. Lost time estimates are not available for the US; however, the Department of Labor and Industries for Washington State estimated that at least 500,000 days were lost in 1971 due to compensable back injuries. The length of disability from low back pain for workers involved in heavy labor averages three to four times longer than for those involved in other work. Comparing severity rates for both low back pain and musculoskeletal complaints with load lifting requirements has shown that injury severity, expressed as number of days lost from work and medical restriction, increases as the maximum load lifted increases. Evaluating individual risk of low back injury was discussed. Experimental and clinical studies have shown that a good medical history and examination that emphasizes evaluating functional attributes related to the specific demands of the job seem to be the best predictors of low back injury.
NIOSH-Contract; Contract-210-77-0088; Back-injuries; Musculoskeletal-system; Anatomy; Musculoskeletal-system-disorders; Work-analysis; Risk-factors; Occupational-health; Lost-work-days; Biomechanics
Occupational safety and health symposia 1977