Musculoskeletal Disorders: Work-Related MSD

Musculoskeletal disorders, which are often soft-tissue injuries, occur when there is a mismatch between the physical requirements of the job and the physical capacity of the human body.

Work-related musculoskeletal disorders (WMSDs) represent approximately one third of workers' compensation costs in US private industry, yet estimates of acceptable exposure levels for forceful and repetitive tasks are imprecise, in part, due to lack of measures of tissue injury in humans.

Causes of Work-related Musculoskeletal Disorders

Specific risk factors associated with Work-related musculoskeletal disorders include repetitive motion, heavy lifting, forceful exertion, contact stress, vibration, awkward posture and rapid hand and wrist movement.

The three primary risk factors that have been associated with Work-related musculoskeletal disorders are repetitious movement, awkward postures, and high force levels.

Effects of Work-related Musculoskeletal Disorders

More than 100 different Work-related musculoskeletal disorders can result from repetitive motions that produce wear and tear on the body. Back pain, wrist tendinitis and carpal tunnel syndrome may all stem from work-related overuse.

In a study, female respondents indicated a higher prevalence of Work-related musculoskeletal disorders than did male respondents in every anatomical area except the knees.

CTS – The most common Work-related Musculoskeletal disorders

Among jobs requiring repetitive movements of the upper limb, CTS is the most common Work-related musculoskeletal disorders. Because the median nerve passes through the carpal tunnel along with the long finger and thumb flexors, it is susceptible to mechanical compression or friction by the tendons themselves.

Positions and movements of extreme wrist flexion, particularly in conjunction with non-neutral forearm pronation-supination, contribute to increases in carpal tunnel pressure and tensile or compressive loading of the median nerve.

This increase in pressure within the carpal tunnel may occlude blood supply, resulting in ischemic damage to both the tendons and the median nerve. Anoxia damages the endothelial lining of venules and capillaries, increasing their permeability and resulting in localized edema.

The edema can lead to an influx of monocytes, and this influx of monocytes can induce the proliferation of fibroblasts and synoviocytes in synovial tissues, which deposit collagen. This collagen deposition is excessive, it may directly contribute to compression of the median nerve.

Other physical risk factors, such as vibration from hand-held tools, may contribute to the development of CTS. Carpal tunnel syndrome is associated with deficits in sensation along the median nerve distribution, weakness of the thenar muscles innervated by the median nerve, hand and wrist pain, and long-term disability, including decreased endurance as measured by the rate of repetitive pinching as well as weakness and clumsiness of grasping ability.

Simple Solutions for Work-related Musculoskeletal Disorders

Simple solutions often work best. Workplace changes to reduce pain and cut the risk of Work-related musculoskeletal disorders need not cost a fortune. For example:

• Change the height or orientation of the product.
• Look at injury and illness records to find jobs where problems have occurred.

• Talk with workers to identify specific tasks that contribute to pain and lost workdays.

• Ask workers what changes they think will make a difference.
• Encourage workers to report WMSD symptoms and establish a medical-management system to detect problems early.
• Find ways to reduce repeated motions, forceful hand exertions, prolonged bending or working above shoulder height.
• Vary tasks of assembly-line workers to avoid repeated stress for the same muscles.
• Fingerless anti-vibration gloves help prevent injuries from repetitive vibration on the job, protecting against musculoskeletal disorder.