Musculoskeletal Disorders in Material Handling

Musculoskeletal Disorders (MSD’s) are injuries and disorders of the musculoskeletal system. They may be caused or aggravated by various hazards or risk factors in the workplace. 001
MSDs can occur in:

muscles
tendons and tendon sheathes
nerves
bursa
blood vessels
joints/spinal discs, and
ligaments

MSD’s do not include musculoskeletal injuries or disorders that are the direct result of a fall, struck by or against, caught in or on, vehicle collision, violence, etc. They are caused by overuse of the musculoskeletal system, whether it be during a single forceful exertion, or through repeated use of the same joint over time. They are often known as “sprains and strains”.

Many body parts can be affected by MSD’s. The back is the most common, but the shoulders, neck, elbows, hands and wrists are also frequently involved. MSD-related pain and discomfort can also occur in the hips, knees, legs and feet. The incidence of tendinitis increases with age as muscles and tendons lose some of their elasticity.

003 A number of medical diagnoses are covered by the term MSD, including:

carpal tunnel syndrome (wrist/hand)
epicondylitis (tennis or golfer’s elbow)
muscle strain
rotator cuff disorder or syndrome (shoulder)
tension neck syndrome
tendonitis or tenosynovitis (anywhere in the body)
back pain

While different body parts can be affected by these disorders, the symptoms of MSD’s are similar no matter where they occur.
The symptoms generally include:

pain with or without movement
swelling and tenderness
reduced range of motion and/or stiffness, and
tingling and/or numbness in nerve-related injuries or disorders.

Understanding the Hazards

There are 3 main risk factors that can contribute to MSD’s in material handling tasks. They are:

Force

Refers to the amount of effort made by the muscles and the amount of pressure on a body part.
All work tasks require some level of force, however if the required force is higher than the capability of the muscle, it can damage muscles or associated tendons, ligaments, and joints.
Injury can occur from a single action that requires a very high level of force or more commonly, occurs due to moderate to high forces generated over long durations, and is more likely when the body is in an awkward posture.

Fixed or awkward postures

Is the position of the joints of the body during an activity.
“Neutral posture” is when the joints are working near the middle of their normal range of motion.
MSD injuries can occur when the joint is not in “neutral posture”, when the joint moves toward the end of the normal range of motion.
The more awkward the posture, the more strain on the joints, ligaments, discs (in the spine) and muscles, and the higher the risk of injury.
A” fixed posture” refers to staying in the same position for a long period of time, and injuries occur as the tissue fatigues while exerting effort to maintain the posture.

Repetition

The risk of MSD increases when the same body parts are used repeatedly with few breaks or chances for rest.
High repetition can lead to fatigue and microscopic tissue damage. If no recuperation of the tissues is allowed through rest or task rotation, injury can occur.
Rest allows specific body parts to recuperate.
If the posture is awkward, fatigue occurs much more quickly.

* Combining the risk factors of Force, Awkward Posture and Repetition increases the risk of injury.

risks (Occupational Health and Safety Council of Ontario (2007). Musculoskeletal Disorders Prevention Series Part 3: MSD Prevention Toolbox - Final Draft. Retrieved on February 15, 2008 from www.iapa.on.ca/documents/MSD_2006%20_Prevention_Toolbox.pdf).

What Are Musculoskeletal Disorders?

Understanding the Hazards