Types of Musculoskeletal Disorders and Injuries

Ergonomics is the science of fitting jobs to workers by taking into account the requirements of the job and peoples’ physical and mental capacities. It is the science of ergonomics that is used to design an appropriate computer workstation. (See Workstation Design). When workstations are not designed appropriately, when non-ergonomically designed computer equipment is used and when jobs and tasks are not well organized, a number of computer related health problems can arise.

Eye and vision problems
Eye and vision problems have been reported; in fact, eye and vision complaints are the most common complaints of computer users. Vision problems can contribute to the physical disorders listed below. We tend to position ourselves so that we can see the images on the monitor, keyboards and documents. However if our vision is blurry, we may lean forward and crane our necks to get a closer look . Such awkward positions increase the risk for physical disorders. It is therefore important to have regular eye check ups. In addition, computer work tends to exacerbate other vision problems. Special computer glasses exist that may help with computer work. Adequate lighting and the prevention of glare also play a role in how our vision is affected during computer use. Eye and vision problems have been reported; in fact, eye and vision complaints are the most common complaints of computer users. Vision problems can contribute to the physical disorders listed below. We tend to position ourselves so that we can see the images on the monitor, keyboards and documents. However if our vision is blurry, we may lean forward and crane our necks to get a closer look . Such awkward positions increase the risk for physical disorders. It is therefore important to have regular eye check ups. In addition, computer work tends to exacerbate other vision problems. Special computer glasses exist that may help with computer work. Adequate lighting and the prevention of glare also play a role in how our vision is affected during computer use.

Stress
Stress is also reported by computer users. The National Institute of Occupational Safety and Health (NIOSH) found that operators of computers experience more job stress than any other occupational group it has studied.

Work related musculoskeletal disorders (WMSD), also known as Cumulative Trauma Disorders (CTD) or Repetitive Strain Injuries (RSI),Work related musculoskeletal disorders (WMSD), also known as Cumulative Trauma Disorders (CTD) or Repetitive Strain Injuries (RSI), are a group of health problems caused by over-use or misuse of muscles, tendons and nerves. WMSDs are caused by any combination of the following factors:

Repetitive Tasks - Repetitive Tasks - Repetitive Tasks - Repetitive Tasks - performing the same movement over and over;

Awkward or Fixed Posture Awkward or Fixed Posture Awkward or Fixed Posture Awkward or Fixed Posture - working in an awkward position or holding the same position for a long time;

Fast Pace Fast Pace Fast Pace Fast Pace - having to work quickly; and/ or

Duration of Task with Insufficient Recovery Time Duration of Task with Insufficient Recovery Time Duration of Task with Insufficient Recovery Time Duration of Task with Insufficient Recovery Time - inadequate rest breaks.

Early symptoms of WMSDs include pain and swelling, numbness and tingling (hands falling asleep), loss of strength and reduced range of motion. These symptoms may appear in any order, and at any stage of the development of the injury. Symptoms may not occur immediately after working and they may occur away from the job. A serious WMSD can develop months after symptoms first appear or it may take years. Some of the more common WMSDs include the following: Carpal Tunnel Syndrome, DeQuervains’s Disease, Trigger Finger, Tennis Elbow, Rotator Cuff, Tendonitis, Tenosynovitis, and Ganglion Cysts. Click here for more information on types of musculoskeletal injuries.

There are many different kinds of musculoskeletal disorders and injuries - muscle and tendon disorders, peripheral nerve disorders, and circulation and nervous system disorders. It is possible to have several different injuries at once. Below are some of the more common disorders and injuries. *

Muscle and Tendon Disorder Hand and Forearm Region
Disorder	Description/Cause	Symptoms
Extensor Tendinitis*	Affects muscles that straighten the finger. Caused by holding hands in the "stop traffic" position, as when using the mouse or keying	Pain on top of the hand near the wrist.
Flexor Tendinitis*	Affects muscles used to bend fingers. Caused by excessive finger motion or gripping of mouse.	Pain in fingers.
Ganglion Cysts: A tendon sheath disorder. Ruptured sheath swells with synovial fluid, causing a bump.	Bumps beneath the skin surface on top of the hand, above and inside the wrist, and around the nails, and knuckles. From excessive bending and/or deviating the wrist or other joint.	Achiness and weakness.
Stenosing Tenosynovitis^@ Types: DeQuervain’s Disease, Trigger Finger	Tendon moves with great difficulty through swollen sheath. DeQuervain’s Disease: affects tendons on side of wrist at base of thumb. From holding thumbs while typing or hard-hitting of space bar. Trigger Finger: tendon gets locked in swollen tendon sheath.	DeQuervain’s Disease: acute pain where wrist and thumb meet when moving thumb or doing "wringing out" tasks. Trigger Finger: locking of finger in bent positions

* - Tendinitis is an inflamed tendon. It occurs when a muscle/tendon is repeatedly tensed - for example, holding the hands rigid or resting the wrists on a desk for long periods of time. If you look at the anatomy of the wrist, it is curved away from any contact surface. You can easily see this by resting your hand/arm on a flat surface. You will see light under the wrist and can probably even pass a thin pen under it. The forearm is shaped this way for the wrists to remain free of surface pressure contact.

@ - In some areas of the body, like wrists, and fingers, tendons pass through sheaths which secrete a lubricant called synovial fluid. If the tendon and sheath rub together, the sheath may swell, resulting in Tenosynovisits.

Muscle and Tendon Disorder Elbow Region
Disorder	Description/Causes	Symptoms
Lateral Epicondylitis	Tendons become irritated. Pain is felt from the elbow down the forearm, and on the outside of the elbow. Known as tennis, bowler’s, or pitcher’s elbow. Associated with desks that are too high.	Pain when straightening arms or contracting them against resistance.
Medial Epicondylitis	Known as golfer’s elbow. From rotation of forearm and bending of wrist at the same time.	Pain on inside of elbow.
Muscle and Tendon Disorder Shoulder Region
Bicipital Tendinitis	Where biceps muscle goes into shoulder joint. From slumped posture or moving arm across desk that is too high or too far away (while using the mouse).	Pain when raising arms to front or moving mouse over a high or faraway desk.
Rotator Cuff Tendinitis: The most common shoulder tendon disorder.	Affects muscles and tendons near shoulder joint. Often from keyboards that are too high.	Pain when reaching behind you with arms in "winged" position.
Muscle and Tendon Disorder Neck and Scapular Region
Trapezius Myositis/Spasm	Inflammation of muscle from repetitive trauma and/or overexertion injury.	Muscle guarding; pain between neck and shoulder; limited neck range of motion; pain in another area.
Paraspinals/Rhomboid/Spasm	Inflammation of muscle from repetitive trauma and/or overexertion injury, may be caused by disk bulge or degenerative joint disease.	Muscle guarding; limited neck range of motion; pain in another area.

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Muscle and Tendon Disorder Peripheral Nerve Disorders
Carpal Tunnel Syndrome: Median nerve in wrist. The carpal tunnel is the bracelet of bone and ligament below the wrist. All the fingers’ tendons, tissues, arteries, veins and nerves pass through it.	The lining of the carpal tunnel becomes irritated and swells. Because the carpal tunnel cannot expand in response to the swelling, there is pressure on the median nerve. Caused by excessive wrist and finger movement, like striking computer keys.	Pressure on the nerve causes numbness and tingling in thumb and fingers; sleep interruption
Guyana’s Canal Syndrome: Ulnar nerve in wrist.	Compression of the ulnar nerve in another wrist tunnel near the carpal tunnel. From keyboarding with hands in the "stop" traffic position or angled to the left.	Loss of sensation, numbness, tingling and muscle atrophy.
Cubital Tunnel Syndrome: Ulnar nerve in elbow.	Entrapment in the underarm of the ulnar nerve. From holding elbows bent at right angles for prolong periods, as computer users do.	Loss of sensation, numbness and muscle atrophy.
Radial Tunnel Syndrome: Radial nerve in forearm.	Compression of the radial nerve.	Pain on both sides of the forearm, difficulty in making a fist. Sometimes mistaken for tennis elbow.
Cervical Radiculopathy (from either acute disk bulge or osteoarthritis)	Nerve roots become irritated by pressure from a bulging disk or by narrowing between vertebrae.	Bulging Disk: muscle spasm in the neck in the morning, difficulty swallowing, limited neck movement. Osteoarthritis: neck pain, should pain, radiating pain in the arm, numbness in an extremity, muscle weakness.
Thoracic Outlet Syndrome	Compression of blood vessels and arteries between neck and shoulder. Involves shoulders and arms. From carrying heavy loads; working with arms elevated; reaching above shoulder level.	Pain in arms; numbness, coldness, weakness in fingers, hand and forearm.

Any computer related health symptoms should be reported immediately to the supervisor and an Incident Report should be completed and forwarded to Risk and Claims and EOHSS. Staff will be referred for medical evaluation by Risk and Claims, and EOHSS can evaluate the workstation for proper design, posture and furniture.

Risk Factors: There are three major categories of risk factors that can contribute to WMSDs: Workstation Design and Equipment, JobTask Design and Organization, and Work Practices.

* EOHSS wishes to thank the Labor Institute for the Communications Workers of America, District 1, for allowing the use of information from its computer training manual for portions of this web page.

Computer Ergonomics and Health