Known Risk Factors
Estimated Costs of Workforce Back Injuries
Factors Limiting Injury Control
Using Haddons's Approach to Injury Prevention
Haddon's Ten Basic Strategies
Addressing the Problem
Injuries to the back are one of the most prevalent and costly work-related musculoskeletal disorders in the United States. Low-back pain adversely affects 1,000,000 workers in the United States every year and is responsible for more lost work days than any other musculoskeletal disorder. In 1998, more than 440,000 people missed work for at least one day due to a back injury, accounting for one quarter of all nonfatal injuries/illnesses causing people to be absent from work. Most workers with back injury return to work quickly, but the minority who do not account for the majority of associated costs and health care.1 On average, people with back injuries miss an average of six working days. However, nearly 20 percent of persons with back injuries missed more than 31 days of work.2 One quarter of all compensation indemnity claims involve back injuries with an economic cost of billions of dollars to industry, without consideration of the pain, suffering and impact upon quality of life.3
In response to increasing costs associated with back injuries, many companies have implemented safety measures, sometimes including ergonomics programs. The industrial use of back belts has increased dramatically, however, none of these steps appears to have had a curbing impact. It is felt that the most effective approach to the prevention of back injuries involves an effective control program and ergonomic design of work tasks. Although there are currently no regulations specific to ergonomic issues, they fall under the OSHA General Duty Clause.
A 1999 National Academy of Sciences study concluded that musculoskeletal disorders are expected to further increase as a result of the changing characteristics of the workplace, the aging of the workforce and increasing numbers of women entering material handling and computer-related tasks.4
Epidemiologic research has provided strong evidence of an association between musculoskeletal disorders and work-related factors with high levels of exposure, particularly when there is exposure to multiple physical factors (e.g., repetitive heavy lifting requiring awkward posture under conditions of extreme cold). Many activities in the workplace contribute to low-back injury and many anatomical causes of pain. At least 25% of work-related low back pain results from overexertion. Jobs that require continuous standing, or office workers with poor seated posture are also at risk for low-back pain. The most common conditions seen are acute low-back strains (which include soft tissue injuries such as muscle strains and tendon or ligament injuries), and these account for as much as 60% of reported low-back injury. Disc herniation and spinal stenosis are also commonly seen. A less common but very disabling type of occupational low back injury is high energy trauma, seen in motor-vehicle crashes, falls and workplace violence.
The most common activity associated with low-back pain are those jobs requiring lifting and forceful movements. Sudden slips or sudden exertion are also common causes of low-back strains. These injuries are commonly seen in workers exposed to slippery floors or nurses working with unstable patients. Poor physical condition puts all workers at increased risk for low-back injuries, as does smoking and increased alcohol intake.5,6,7
Exposure to whole-body vibration, for which exposure has been causally linked to disorders of the lower back, includes driving cars, trucks and industrial vehicles.
Nearly one third of non-fatal occupational musculoskeletal injuries which involve lost workdays occur in the service sector, and manufacturing following at 21%. Most of these involved exposures to risk factors by operators, fabricators and laborers.8 Bureau of Labor Statistics data indicate that more than three million workers are involved in industries with the highest incidence rates of overexertion in lifting and repetitive motion although the exact numbers of workers involved in tasks which encounter specific risks is unknown.
Known Risk Factors
The strongest evidence links back injuries to lifting/forceful movement and whole body vibration, with evidence of work-relatedness found for awkward posture and heavy physical work.9 Improper techniques for lifting, pushing, pulling, carrying, bending or twisting the low back also put workers at risk for low-back injury. Moreover, it has been demonstrated that complex, simultaneous trunk motions are associated with increased low back disorder risk.10
The degree of risk is compounded by individual employee factors. There is evidence to support the increased risk associated with elevated body mass index and history of back injuryin fact, a previous history of back pain is asserted to be the most consistent predictor of future difficulty.11 These same risk factors increase risk for low back injury in non-workplace settings, making the determination of work-relatedness more difficult.
Estimated Cost of Workforce Back Injuries
Low-back disorders account for almost 30% of injury requiring time away from work. Its estimated economic impact in lost productivity, health-care related expenses, and disability are staggering. The average cost of a low-back associated workers compensation claim is nearly $8,500. This is double the cost of the average injury claim. The total estimate for the United States ranges between $50 and $100 billion per year. A large portion of this cost is directly workers compensation related. (NORA, 1998)
Factors Limiting Injury Control
Scientific solutions to the problem of work-related back injuries have been difficult to obtain because of the multifactorial etiology of musculoskeletal disorders. There remains a lack of sound evidence supporting specific preventive measures, with conflicting claims regarding the efficacy of available measures, such as back belts. Many suppliers claim remarkable decreases in injury rates, however other sources such as NIOSH feel there is not enough evidence to support their use.
Employers remain reluctant to implement preventive measures for a multitude of reasons, including perceived financial costs. However, data suggest that a more proactive and less reactive approach provides a greater return on investment for the employer, but long-term savings are not often the immediate concern for politicians and employers. Preventive efforts may further be impeded by : (a) industry attempt to avoid stigma; (b) fear of government regulation; (c) objections to a traditional medical model; (d) unfamiliarity with the benefits of prevention; and (e) perception that risk assessment is ineffective.12
Finally, research findings have not been consistent likely due to difficulties separating occupational back pain from the underlying high incidence of low back pain found in the general population.13
Strategic Planning: Back Injury Prevention
There is no single variable which has proven to be effective alone in decreasing the incidence of back injuries. Educational strategies have had equivocal results in the prevention of low back problems.14
Rather, a comprehensive approach is warranted. NIOSH recommends the implementation of an ergonomics program that focuses on redesign of an employees work environment and tasks to reduce the risk of workplace back injury. Components which may minimize back injuries include: worker training in proper lifting techniques, adjusting the height at which materials are handled, reducing the size of objects and physical conditioning. In addition, engineering technology may be applied to reduce the need for awkward lifting postures and tasks may be altered to remove excessive handling, reaching or unusual forces. NIOSH does not recommend the use of back belts among workers who have no history of prior back injury.15
Using a biopsychosocial approach to the prevention of disability, it has been suggested that secondary prevention interventions be designed to address modifiable cognition-based factors, with particular emphasis on expectations of recovery.16 One reviewer found that medical variables alone are unable to predict return to work after acute back injury; however, a model which incorporated workers interpretation of their prognosis was better able to accurately predict return to work.17
Using Haddons Approach to Injury Prevention
Haddons Ten Basic Strategies
1. Do not create the hazard. Prevent the storage of materials at heights which may be hazardous to workers. Prohibit the manufacture of any items of large size, irregular contours or other risk factors for back injury. This is not practical when strictly applied as industrial processes require large scale materials.
2. Reduce the amount of hazard. Rather than the purchase of materials in 50 or 100 pound bags/boxes, use smaller packaging. Specify maximum allowable weights for a given set of task requirements.
3. Prevent release of the agent. This may involve extensive education of workers. Consider assistive safety cables for materials handling to prevent uncontrolled movement of objects.
4. Modify release of the agent. Engineering controls may include mechanical aids such as pneumatic lifts, conveyors or automated materials handling equipment. Ramps with security stops to prevent runaway carts.
5. Separate in time or space. Use appropriate packaging (such as handles) such that materials may be maintained the proper distance from the body. Administrative controls which limit repetitive motions.
6. Separate with a physical barrier. Consider back belts. Properly secure elevated items to prevent falling objects which may contribute to back injury.
7. Modify surfaces and basic structures. Adjust height of pallet or shelf such that lifting occurs between knee and shoulder height. Use non-slip flooring to minimize falls which contribute to back injury.
8. Increase resistance of the structure or person. Implement strength training, stretching and ideal weight maintenance programs to decrease individual factors contributing to risk.
9. First aid and emergency response. Train employees in first aid procedures and maintain written response protocols. Ensure access to medical care and reporting systems.
10. Acute care and rehabilitation. Assist with access to medical services and provision of rehabilitation and return to work planning. Retraining for workers whose injuries preclude return to previous job tasks.
Addressing the Problem of Occupational Back Injury
While research continues to provide valuable information for the prevention of back injuries in the workplace further research is required in light of the continuing problem.
The effectiveness of available ergonomic controls must be documented to encourage industry to adopt practices that protect the back health of workers. Further study of engineering contols, particularly studying their cost-effectiveness, will provide further evidence to argue for a more proactive approach. The most effective medical management and return to work practices must take into account individual biological characteristics, cognitive expectations and social situation to minimize disability following a back injury in the workplace.
The most appropriate response to the problem of back injury will incorporate each of the components identified in the analysis utilizing the strategies of Dr. Haddon, as outlined above. This comprehensive approach requires the integration of safety considerations into the planning of work tasks, assessment of all work activities to ensure that tasks do not exceed a workers physical ability, elimination of biomechanical hazards, adoption of administrative practices specifically aimed at injury reduction (including a written program), on-going training for all workers in lifting mechanics and best practice techniques, implementation of a surveillance program to identify high-risk tasks, encouragement of general employee fitness and utilization of a medical management program.
1. Hazard RG, Haugh LD, Reid S, et al. Early Prediction of Chronic Disability After Occupational Low Back Injury. Spine. 1996;21(8):945-951
4. National Academy of Sciences. Work Related Musculoskeletal Disorders: Report, Workshop Summary, and Workshop Papers. Washington, DC: National Academy of Sciences, National Research Council, Institute of Medicine; 1999:1-240.
5. Leboeuf-Yde C. Alcohol and low-back pain: a systematic literature review. J Manipulative Physiol Ther 2000;23:343-6.
6. Wassell JT, Gardner LI, Landsittel DL, et al. A prospective study of back belts for prevention of back pain and injury. JAMA 2000;284:2727-32.
7. Porter SE, Hanley EN, Jr. The musculoskeletal effects of smoking. J Am Acad Orthop Surg 2001;9:9-17.
10. Fathallah FA, Marras WS, Parnianpour, M. The Role of Complex, Simultaneous Trunk Motions in the Risk of Occupation-Related Low Back Disorders. Spine. 1998;23(9):1035-1042.
11. Burton AK, Erg E. Back injury and work loss. Biomechanical and psychosocial influences. Spine. 1997;22(21):2575-80.
12. Melhorn JM, Gardner P. Prevention of Musculoskeletal Disorders in the Workplace. Clinical Orthopaedics and Related Research. 2004;1(419):285-296.
13. Fransen M, Woodward M, Norton R, et al. Risk Factors Associated With the Transition From Acute to Chronic Occupational Back Pain. Spine. 2002;27(1):92-98.
14. Hazard RG, Reid S, Haugh LD, et al. A Controlled Trial of an Educational Pamphlet to Prevent Disability After Occupational Low Back Injury. Spine. 2000;25(11):1419-1423.
16. Schultz IZ, Crook JM, Berkowitz J, et al. Biopsychosocial Multivariate Predictive Model of Occupational Low Back Disability. Spine. 2002;27(23):2720-2725.
17. Hunt DG, Zuberbier OA, Kozlowski AJ, et al. Are Components of a Comprehensive Medical Assessment Predictive of Work Disability After an Episode of Occupational Low Back Trouble? Spine. 2002;27(23):2715-2719.
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