Preventing Low Back Injuries in the Workplace

By Thomas E. Menke, MD

Back pain is the most common cause of absence from work for both men and women between 30 and 65 years of age. In the United States alone, 250 million work days are lost each year because of back pain, costing industry and society billions of dollars per year. With this obvious financial incentive, much research has been done in the area of low back injury in the work place.

The search for risk factors that predispose a person to low back injury has been confusing and has often uncovered conflicting information. The two main categories of risk factors are physical and psychosocial.

Physical risk factors include those pertaining to the person and those pertaining to the job. Person-related risk factors include age, sex, and conditioning. Most studies of the work force have shown an increased incidence of back injury with age. An equal incidence of back pain for men and women has been found. The one exception here is the postmenopausal osteoporotic woman, whose incidence of back pain and back injury is higher than that of men of the same age. Recent studies, with careful strength measurement, indicate that proportionate strength and conditioning of the back, abdomen, arms, and legs may be protective against back injury.

Job-related physical risk factors for back injury include frequent lifting of weights of more than 10 kilograms, frequent bending and stooping, truck driving, and exposure to whole-body vibrations. Each of these risk factors has been shown, in certain studies, to increase the risk of low back pain. However, other studies have found that these factors did not appear to increase the incidence of low back pain. The search for physical risk factors for low back injury in the work place has indeed been confusing.

Many newer studies indicate that psychosocial factors may have more predictive value than physical factors in determining who is at risk for back injuries in the work place. These psychosocial risk factors for low back pain include job dissatisfaction, incompatibility with colleagues and supervisors, and poor sense of self worth.

Interventional training programs can decrease the number of reported back injuries in the work place as well as the number of days lost to such injuries. This effect has been seen in controlled studies that have found that employees in training programs had fewer injuries and missed far fewer work days than their colleagues who had no such training. These training episodes consisted of 20 minutes of instruction in exercise and in proper body mechanics. The most effective programs occurred during normal working hours once or twice a week. In the end, the study group ended up with improved lumbar muscle strength, significantly fewer episodes of back pain, and fewer work days lost.

Studies that include the use of lumbosacral corsets have suggested that these devices are beneficial in addition to training but that they have less effect if they are the only intervention used. Detrimental effects of the use of these corsets have not been found. There is no evidence to suggest loss of strength as the result of the intermittent use of a lumbosacral corset.

Intervention in the form of training programs and corsets has been shown to be cost efficient. When compared to control groups, the exercise groups have shown a significantly lower number of days lost to back injury. The savings from a decreased number of days lost has far offset the expense of instituting the program.

The perceived benefits of these training programs are many. Training programs have been shown to increase lumbar and abdominal strength. They also improve lifting technique and heighten the awareness of the need for using proper lifting technique. All of these are positive physical changes that would appear to naturally decrease the risk of injury.

There are other less easily measured effects that may be more significant. These training programs let employees know that someone "finally" cares about them. These programs help foster a camaraderie among employees and possibly even between employee and supervisor. They may help the workers take more pride in themselves because of their improved physical fitness. All of these factors can combine to improve the employees' sense of self worth.

Some straightforward recommendations for avoiding the physical risk factors for low back pain are listed in the table below. Eradicating the psychosocial risk factors poses a more formidable challenge for both employers and health care professionals.

Tips for Back Care in the Workplace

Lifting
Bend your knees
Lift with your legs
Lift objects only chest-high
Get help when lifting heavy objects
Standing
Change positions often
Maintain good posture
Wear shoes with cushioned soles
Driving
Move car seat as far forward as comfortable
Sit straight
Use lumbar support or place a rolled-up towel behind your low back
Sitting
Use a chair low enough so that your feet are flat on the floor and your knees are level with your hips
Sit firmly against the back of the chair
Use lumbar support

Sources:

Back owner's manual: a guide to the care of the low back. Krames Communications, San Bruno, CA, 1995.
Bigos SJ, Battié MC, Spengler DM, Fisher LD, Fordyce WE, Hansson TH, Nachemson AL, Wortley MD. A prospective study of work perceptions and psychosocial factors affecting the report of back injury. Spine 1991;16:1-6.
Gundewall B, Liljeqvist M, Hansson T. Primary prevention of back symptoms and absence from work. Spine 1993;18:587-594.
Walsh NE, Schwartz RK. The influence of prophylactic orthoses on abdominal strength and low back injury in the workplace. Am J Phys Med Rehabil 1990;69:245-250.

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