Answers to the most frequently asked questions about musculoskeletal disorders.
What are Musculoskeletal Disorders?
Musculoskeletal disorders (MSDs) are injuries to the muscles, nerves, tendons, ligaments, joints, cartilage, or spinal discs. MSDs are not typically the result of any instantaneous or acute event (such as a slip, trip, or fall) but reflect a more gradual or chronic development.
Other expressions used to describe MSDs include
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Repetitive Strain Injuries (RSIs)
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Cumulative Trauma Disorders
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Overuse Injuries
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Repetitive Motion Disorders.
Medical terms used to describe MSDs to various parts of the body include low back pain, tendinitis, bursitis, carpal tunnel syndrome, epicondylitis, trigger finger, thoracic outlet syndrome, carpet layers' knee, and degenerative disc disease.
Why are MSDs a Problem?
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MSDs may cause a great deal of pain and suffering among afflicted workers.
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MSDs are among the most common lost-time injuries. They average approximately 30% of the total annual lost-time injuries among IHSA member firms (in the construction, transportation, electrical utilities, and aggregates sectors).
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MSDs are among the most costly occupational problems. They account for approximately 23% of Workplace Safety and Insurance Board (WSIB) costs.
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Job activities that may cause MSDs span diverse workplaces and operations.
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MSDs may decrease productivity and the quality of products and services. Workers experiencing aches and pains on the job may not be able to do quality work.
What Risk Factors Contribute to MSDs?
The following are recognized as important risk factors, especially when they occur at high levels and in combination.
Forceful Exertion
Force is the amount of effort required to perform a task or job. The amount of force one can exert depends on one's posture and the number of exertions performed. The more force that is exerted, the greater the stress on the body. Lifting, pushing, pulling, and gripping a tool are examples of activities that require exerting force or muscle effort.
Repetitive Movements
Movements performed over and over are described as repetitive movements. But a repetitive movement can also be an awkward posture held for long periods. These movements can be of risk to the worker because of continual stress placed on one body part without sufficient muscle recovery time. Nailing a deck, screwing drywall, and tying rebar are examples of repetitive tasks.
Awkward Postures
Postures are the positions of body parts. Unnatural positions or awkward postures are those in which joints are held or moved away from the body's natural position. The closer the joint is to its end the range of motion (for instance, bending the back forward as far as possible), the greater the stress placed on the soft tissues of that joint, such as muscles, nerves, and tendons.
Secondary Risk Factors
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Contact pressure is any external pressure that is applied to soft tissues and puts stress on those tissues. Holding tools where handles press into parts of the hand or arm is an example of contact pressure.
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Vibration is a secondary risk factor which can cause damage to nerves and blood tissues as well as other soft tissues.
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Gloves can be a risk factor for musculoskeletal disorders if they do not fit properly or if they restrict the movement of the fingers and hands.
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Temperature can also affect muscles. Cold temperatures increase the stress placed on soft tissues by reducing their range of motion and flexibility. Heat affects the work rest cycles required due to the increase in fatigue and the need for muscle recovery.
Combination Effect
The chance of injury increases when two or more MSD risk factors combine in one job. One factor alone is unlikely to cause a high risk of injury. For example, performing a forceful lift once places a worker at less risk than performing a forceful lift several times an hour.
How can MSDs be Controlled?
Two approaches are widely accepted for controlling workplace ergonomic hazards.
Engineering Controls
These are measures taken to modify the forcefulness, repetitiveness, awkwardness, vibration levels, physical pressures, or environmental extremes connected with a particular job. Engineering controls are the preferred approach to prevent MSDs. Examples include modifications of 1) the workstation layout, 2) the selection and use of tools, 3) work materials, and 4) work methods.
Administrative Controls
Administrative controls are management-directed work practices and policies. Administrative control strategies include 1) changes in job rules and procedures such as scheduling more rest breaks, 2) rotating workers through physically tiring jobs, and 3) training workers to recognize ergonomic risk factors and to learn techniques for reducing stress and strain while performing their job. Although engineering controls are preferred, administrative controls can be helpful as temporary measures until engineering controls can be implemented or when engineering controls are not technically feasible. Since administrative controls do not eliminate hazards, the necessary precautions and safeguards must be followed. Interventions to control MSDs can range from the simple to the elaborate. Modifications to existing designs can be costly, but in many circumstances the interventions can save time and money.
What are Some Construction Controls?
The following are examples of engineering, administrative, and PPE controls aimed at reducing MSDs.
Engineering Controls
- Adjustable Material Handling Equipment - Utilize equipment such as adjustable conveyors and lift tables to match the worker's height, reducing the need for repetitive bending or reaching.
- Ergonomic Tool Design - Select tools with ergonomic features such as padded handles and reduced vibration to minimize grip force and wrist strain.
- Mechanical Assistance Devices - Increase the availability and use of devices like carts, dollies, hoists, or other mechanical handling devices. Increase the use of ladder hoists, gin poles, daisy chains, or cranes to move materials. Use chain falls, motorized buggies, carrying handles, or extension handles for carrying large or awkward materials like drywall.
Administrative Controls
- Job Rotation - Implement a job rotation schedule to reduce the duration of exposure to high-risk tasks and distribute the load across more workers, decreasing the chance of overuse injuries.
- Scheduled Breaks - Introduce frequent short breaks to reduce fatigue and give muscles time to recover, especially in tasks involving high physical demands.
- Training Programs - Conduct regular training sessions focused on proper lifting techniques, the use of mechanical aids, and the importance of reporting early symptoms of musculoskeletal disorders.
- Work Planning - Plan tasks to allow the use of mechanical aids and ensure materials are delivered close to where they are used, minimizing unnecessary handling.
Personal Protective Equipment
- Supportive Gear - Provide knee pads when working on the ground or shoulder pads when carrying loads on your shoulders.
- Anti-Fatigue Matting - Use anti-fatigue mats in areas where workers stand for long periods to reduce leg and back discomfort.
Integration of Controls
Combining these controls can effectively reduce the risk of injury.
- For instance, when lifting heavy materials like drywall, use mechanical lifting aids (engineering control), and ensure workers are trained in their use (administrative control).
- In tasks requiring precision drilling and chipping, use an ergonomically designed hammer or drill, such as anti-vibration, which can be paired with frequent mini-breaks (administrative controls) and providing anti-vibration gloves (PPE) to maximize the risk of injuries and improve efficiency.
Implementing these controls not only helps reduce the incidence of musculoskeletal injuries but also enhances productivity and worker satisfaction by creating a safer and more comfortable working environment.