OCCUPATIONAL HEALTH

Work related musculoskeletal disorders (WMSD’s) include a group of conditions that involve the nerves, tendons, muscles, and supporting structures such as intervertebral discs. They represent a wide range of disorders, which can differ in severity from mild periodic symptoms to severe chronic and debilitating conditions. Examples include carpal tunnel syndrome, tenosynovitis, headaches, and low back pain. WMSD’s can cause symptoms such as pain, numbness, and tingling; reduced worker productivity; lost time from work; temporary or permanent disability; inability to perform job tasks; and an increase in workers compensation costs. WMSDs are by far the most common form of work-related ill-health problem.

A broad rule of thumb is that the true costs of all workplace injuries is at least triple the cost of worker’s compensation benefits.

Musculoskeletal disorders are often confused with ergonomics. Ergonomics is the science of fitting workplace conditions and job demands to the capabilities of workers. In other words, musculoskeletal disorders are the problem and ergonomics is a solution.

What Are the Risk Factors for WMSDs?

Repetitive, forceful, or prolonged exertions of the hands; frequent or heavy lifting, pushing, pulling, or carrying of heavy objects; prolonged awkward postures; and vibration contribute to WMSDs. Jobs or working conditions that combine risk factors will increase the risk for musculoskeletal problems.

The level of risk depends on how long a worker is exposed to these conditions, how often they are exposed, the level of exposure, and the amount of recovery time between exposures.

How Common Are MSDs?

Musculoskeletal disorders of any cause are among the most prevalent medical problems, affecting 7% of the population and accounting for 14% of physician visits and 19% of hospital stays.

In 2003, there were over 40,000 musculoskeletal injuries to workers in Ontario, largely due to overexertion or ergonomic problems. That’s over 40 percent of all workplace lost-time injuries. According to the Workers Safety and Insurance Board of Ontario, work-related MSDs in 2003 cost businesses in Ontario approximately $60,000 per injury in lost productivity, retraining, rehiring, damage to equipment and workers compensation insurance.

What can be done to prevent WMSDs?

Much can be done to prevent WMSDs.

  1. Ergonomics programs to prevent WMSDs can be tailored to a particular workplace.
  2. Individual prevention – strengthening and stretching programs.

Work-related Musculoskeletal injuries (MSIs) are the fastest growing category of work-related illness. Across Canada, 1/3 to 1/2 of all workers’ compensation claims are due to MSI, the most common and most costly being low back pain and carpal tunnel syndrome. It is estimated that 1/2 of all MSIs can be prevented, particularly in those workplaces that have a high incidence of MSIs such as Manufacturing and health care sectors.

Work-related musculoskeletal injuries result when there is a mismatch between the physical capacity of workers and the demands of the job. Many of these MSIs are caused by risk factors such as repetitive and forceful movements, vibration, temperature extremes, and awkward postures. These risk factors arise from improper work methods and improperly designed workstations, tools, and equipment. Examples of musculoskeletal injuries include low back pain, tennis elbow (an inflammation of a tendon in the elbow) and carpal tunnel syndrome (a condition affecting the hand and wrist).

Ergonomics attempts to match the job requirements with the person’s physical capabilities. Ergonomics covers all aspects of a job, from the physical stresses it places on joints, muscles, nerves, tendons, and bones, to environmental factors which can effect hearing, vision, and general comfort and health.

If good fit is achieved, the stresses on people are reduced, they are more comfortable, they can do things more quickly and easily, they make fewer mistakes, and are less prone to injury.

For more information about ergonomics visit the Association of Canadian Ergonomists web site.

For Additional Ergonomics services, visit Ergoprime .

Postural strain injuries
In a relaxed state, muscles do not require much blood, and the supply of blood matches the muscle’s demands. When the muscles are involved in rhythmic contractions, such as during walking, running or cycling, the blood circulation to the muscles increases and matches the increased demands of the muscles (unless the activity is very intense). When a muscle is contracted for a prolonged duration, the blood supply to the muscle is restricted due to continuous compression of the blood vessels by the muscle. At the same time, the muscle’s requirement for oxygen has increased due to the contraction, so the blood supply to the muscles is not matching the muscles demands.

When this chronic, static muscle contraction occurs, your body responds by sending cells to the area that will lay down fibrous connective tissue within the muscle to help re-enforce and support the muscle. Over a long period of time, the muscle slowly becomes weaker, more ”leathery”, and painful knots or trigger points will develop in the muscle.

The most common cause of static muscle contraction is poor posture. Poor posture can occur while standing, sitting, sleeping, playing sports, working, or doing hobbies. The most effective approach is prevention, which can be addressed by the individual or the activity

Prevention of postural strain

Individual interventions may include:

  • Postural education for sitting, standing and sleeping
  • Stretching and strengthening exercises
  • Nutritional advice
  • Advice on technique and biomechanics of the activity.

Activity interventions may include:

  • Job analysis and ergonomic modifications to the activity

Clinical Management of postural strain

If this condition already exists and all attempts to self manage the condition fail to relieve the pain or stiffness, it is time to get help in managing the problem. Assuming that all of the self-management approaches are being addressed, the clinical management of chronic postural strains may involve the following and usually in this order:

  • Restore the muscles to their normal state: This may involve Active Release Technique® and massage therapy to eliminate any scar tissue, physical modalities such as ultrasound or electrical modalities, mobilization and assisted stretching techniques, joint manipulation, nutrition, or acupuncture.
  • Eliminate any compensation patterns: Your body will adapt to the way you use it. If chronic postures have been adopted for a period of time, or if pain has been present for a prolonged period, the body has created compensation patterns to the conditions. When the pain or posture has been corrected, your body may still be using these compensation patterns. They may include asymmetrical movement patterns such as limping, or postural habits such as slouching. Before any stabilization or strengthening can begin, these patterns must be eliminated or they will be perpetuated and lead to future problems.
  • Stabilize the affected areas: The fine-tuning of motion in most joints of the body is controlled by smaller “stabilizing” muscles. If these muscles are injured or dysfunctional, then the joint will not move properly when the larger “force generating” muscles contract. If this occurs, then the joint and other tissues (tendons and ligaments) are stressed. This can lead to chronic dysfunction and repeated injury. Once the tissues have been returned to a normal state, then these small stabilizing muscles must be retrained to function properly. Exercises that train these muscles include stability exercises such as those performed on an exercise ball, wobble board, or any other device that challenges balance. The joint stabilizing muscles must be retrained before any strength exercises are performed to ensure that the joints are stable and will not be re-injured.
  • Strengthen the affected areas: The final stage of rehabilitation is strengthening the larger “force generating” muscles through resistance training programs. These programs may take advantage of weights, elastic tubing, lifting body weight, or any other program that will fit into the individuals goals, lifestyle and resources.

Repetitive strain injuries are almost twice as common as all other types of workplace injuries and illness. These claims alone account for 60 percent of all the WMSD claims. There are other terms associated with repeated physical exertions including: musculoskeletal disorder, occupational musculoskeletal disorder, repetitive stress or strain disorder or syndrome, repetitive motion syndrome, overuse syndrome, and work-related disorder.

RSI’s occur due to small, but additive tissue damage sustained through performance of repetitive tasks. They often develop in the absence of acute injury and results in chronic localized pain and dysfunction with or without objective physical changes (such as swelling).

What are the risk factors in developing RSI’s?

The three primary physical risk factors that contribute to the development of RSI’s are:

  • Force: The muscular force that is required by the worker to complete the task.
  • Exposure: This includes the frequency with which the task must be performed, the duration of each task, the duration of the rest between tasks, and the duration of the work day.
  • Posture: The postures that must be adopted by the worker during the execution of the task. The farther a workers posture is from neutral, the higher the risk of injury.

If only one risk factor is present, the risk of injury is low. As more risk factors are added to the task, the risk of an RSI occurring increases.

In addition to the primary risk factors, there are many secondary risk factors that can increase the jobs risk of RSI. These include:

  • Vibration
  • Lighting
  • Temperature
  • Noise
  • Personal protective equipment
  • Psychosocial factors
  • Mechanical contact stress

Additional factors can play a role in how an individual will respond to repeated physical exertions. These include:

  • The individual’s physical strength and conditioning
  • Nutrition
  • Physical activities at home and at play
  • Emotional and psychological issues
  • Attitudes toward work

Prevention and management of RSI’s

Intervention has a positive effect in preventing and treating cumulative trauma disorders. One study demonstrated that for every dollar spent on intervention programs, six dollars were saved in terms of direct costs associated with workers’ compensation claims. RSI’s can be prevented through intervention directed to both the individual and the job.

Individual interventions may include education on:

  • Exercise including cardiovascular, strengthening and stretching
  • Work pacing
  • Working postures and positioning
  • Nutrition
  • Stress management

Job interventions may include:

  • Ergonomics evaluations to improve workplace design
  • Evaluation of psychosocial and cognitive job factors

Clinical management of RSI’s

If the RSI already exists and all attempts to self manage the condition fail to relieve the pain or stiffness, it is time to get help in managing the problem. Assuming that all of the self-management and job management approaches are being addressed, the clinical management of RSI’s may involve any of the following and usually in this order:

  • Restore the muscles to their normal state:This may involve Active Release Technique® and massage therapy to eliminate any scar tissue, physical modalities such as ultrasound or electrical modalities, mobilization and assisted stretching techniques, joint manipulation, nutrition, or acupuncture.
  • Eliminate any compensation patterns: Your body will adapt to the way you use it. If chronic postures have been adopted for a period of time, or if pain has been present for a prolonged period, the body has created compensation patterns to the conditions. When the pain or posture has been corrected, your body may still be using these compensation patterns. They may include asymmetrical movement patterns such as limping, or postural habits such as slouching. Before any stabilization or strengthening can begin, these patterns must be eliminated or they will be perpetuated and lead to future problems.
  • Stabilize the affected areas: The fine-tuning of motion in most joints of the body is controlled by smaller “stabilizing” muscles. If these muscles are injured or dysfunctional, then the joint will not move properly when the larger “force generating” muscles contract. If this occurs, then the joint and other tissues (tendons and ligaments) are stressed. This can lead to chronic dysfunction and repeated injury. Once the tissues have been returned to a normal state, then these small stabilizing muscles must be retrained to function properly. Exercises that train these muscles include stability exercises such as those performed on an exercise ball, wobble board, or any other device that challenges balance. The joint stabilizing muscles must be retrained before any strength exercises are performed to ensure that the joints are stable and will not be re-injured.
  • Strengthen the affected areas: The final stage of rehabilitation is strengthening the larger “force generating” muscles through resistance training programs. These programs may take advantage of weights, elastic tubing, lifting body weight, or any other program that will fit into the individuals goals, lifestyle and resources.