Cumulative Trauma Disorders (CTDs) are Computer-Related Ergonomics Problems that are defined as disorders or diseases of the neuromusculoskeletal system due to chronic, or accumulative micro trauma.  The neuromusculokeletal system is designed to tolerate work and physical stress.  However, when the physical stress exceeds the body’s tolerance level, trauma and injury results.  Trauma or injury to the neuromusculoskeletal system can be a result of direct physical stress or force or it can be from the internal stresses formed within the neuromusculoskeletal tissues.  Macro-trauma, is an immediate injury that occurs from a single, direct force of a high intensity, the damage or injury is obvious and immediate, resulting in pain and loss of function.  An example of macro-trauma is a fracture sustained due to a fall or a knee ligament sprain during a football tackle.  Micro-trauma is tiny, microscopic, damage that is painless and not always immediately detected.  Micro trauma occurs daily, and usually heals overnight.

How Do Cumulative Trauma Disorders Develop?

The neuromusculoskeletal tissues work as a system to perform certain functions, including: activities of daily living, recreational activities and work activities.  The muscle fibers generate an internal force or contraction, resulting in internal pressures inside the muscle.  The force is then transmitted along to the tendons and the skeletal system to move the bones and perform voluntary movement.  When bones move, they rotate about an axis, or joint, when this occurs, the joint experiences compressive forces.  When the neuromusculoskeletal system experiences stresses and internal forces that overload the tissues, local tissue fatigue can occur.  This local tissue fatigue can lead to micro tearing of the tissues, this is also called micro trauma.  Micro trauma or wear and tear damage does occur on a daily basis. 

When micro-trauma continues over a period of time at a rate that exceeds the rate of the body’s ability to repair itself, the damage or trauma accumulates.  The accumulation of trauma, over time, results in pain and loss of function.  Further damage and trauma can lead to the formation of scar tissue, changes in body or tissue chemistry and even degenerative changes that may also affect motion, strength and function. 

A clinical sign of an injury or disease is the objective clinical evidence of a disease or injury.  Some signs of injury include: swelling, loss of motion or strength, loss of reflexes and numbness or tingling in nerve distributions.  A clinical symptom is the subjective evidence of an injury or disease observed by the person.  Symptoms can include: pain, numbness or tingling and a burning sensation.

Common clinical signs and symptoms of Cumulative Trauma Disorders include:  Pain, swelling, nocturnal pain (pain at night), numbness or tingling, loss of motion and moss of strength.  These signs and symptoms are the body’s warning signals that there is too much damage followed by too little repair time.

Common Cumulative Trauma Disorders experienced by Computer Users:

Carpal Tunnel Syndrome (CTS)

According to the National Institute of Occupational Safety and Health, carpal tunnel syndrome is the most commonly reported musculoskeletal disorder in the workplace.  Carpal Tunnel Syndrome (CTS) results from the compression and inflammation of the medial nerve as it passes through the carpal tunnel of the wrist.  The carpal tunnel is an anatomical space formed by the eight wrist bones and the transverse carpal ligament.  The nine finger flexion tendons, median artery and nerve all pass through the carpal tunnel.  When the structures with in the carpal tunnel become compressed, they swell, become inflamed, causing pain and numbness and tingling in the ulnar nerve distribution of the hand.

Common Causes

Common causal or risk factors for the development of CTS include:

• Highly repetitive hand or wrist motions, such as repetitive keying.
• Direct pressure on the wrist, not using proper wrist rest.
• Prolonged, extreme or forced positions of the wrist.

 Tendonitis

Tendonitis is defined as the inflammation of the tendon.  Tendons attach muscles to bones to direct forces and allow voluntary movement.  The tendon becomes irritated or inflamed when forces overstress the tendon. 

Common Causes

Common causal or risk factors that can result in an overstressed tendon include:

• Overstressing tendons
• Friction forces that are developed as the tendons rub against bones or ligaments such as not using proper wrist rest.
• Repetitive motions as with keying.
• Awkward positions due to poor ergonomic set up and positioing.
• Forceful movements.

  Tenosynovitis

Tenosynovitis is defined as the local inflammation of the tendon sheath.  The synovial sheath covers the tendon.  This sheath acts to protect and allow the tendon movement, and sliding, thus minimizing frictional forces.  When excessive forces are placed on the tendon, the sheath becomes inflamed and swollen.  DeQuervain’s is an example of a common tenosynovitis that occurs at the thumb. 

Common Causes

Common causal or risk factors that can result in an inflamed tendon sheath include:

• Overstressing tendons.
• Friction forces that are developed as the tendons rub against bones or ligaments.
• Repetitive motions due to excessive keying.
• Awkward positions due to poor ergonomic set up or positioning.
• Forceful movements.
• Direct pressure or contact stress due to improper wrist support.

Epicondylitis

Lateral epicondylitis, also known as “tennis elbow” is the inflammation of the tendons of the forearm extensor group at the origin point on the elbow.  Medial epicondylitis, also known as “golfer’s elbow”, is the inflammation of the tendons of the forearm flexor group at the origin point on the elbow. 

 Common Causes

Common causal or risk factors that can result in an inflamed tendon include:

• Overstressing tendons.
• Friction forces that are developed as the tendons rub against bones or ligaments.
• Repetitive motions due to keying.
• Awkward positions due to poor ergonomic set up or posture.
• Forceful movements.
• Direct pressure or contact stress due to improper wrist rest.
• Caused by rotation against resistance of the forearm due to poor positioning
• Rapid extension of the wrist when the forearm is pronated (palm down.) due to poor ergonomic set up while typing.

  Muscle Strain

A muscular strain is an injury due to the overstretching of muscle fibers, beyond their limit, as a result of forceful tension, effort or overuse.  Actual deformation or tearing of the fibers can result.  There are three types of strains:

 Common Causes

Common causal or risk factors that can result in a muscle strain include:

·         Overstressing tendons and muscle fibers.

·         Repetitive motions.

·         Awkward positions.

·         Forceful movements.

·         Direct pressure or contact stress.

·         Excessive muscular contractions.

·         Twisting forces.

·         Overuse. 

Ligamentous Sprain

A ligamentous sprain is an injury due to the overstretching or tearing of ligaments, beyond their limit, as a result of forceful tension, effort or overuse.  Actual deformation or tearing of the fibers can result.  There are 3 types of sprains: 

Common Causes

Common causal or risk factors that can result in a ligamentous sprain include:

• Overstressing ligamentous fibers.
• Repetitive motions.
• Awkward positions.
• Forceful movements.
• Direct pressure or contact stress.
• Twisting forces.
• Overuse.

Computer-Related Ergonomics Problems:

Although the majority of Computer-Related Ergonomics Problems relate to the musculoskeletal system, don't forget about the Ergonomics Eye Problems that nearly 90% of all computer users suffer from. Read more about Ergonomics Problems and Ergonomics Eye Problems on our site! 

Prevention is Best Medicine!

Aways set up your desktop or laptop computer workstation correctly according to guidelines. See the ergonomic set up guidelines on the Posture Tips page of our website. Make sure you set up your computer workstation properly before you get signs and symptoms of CTDs. If you are already having signs of a CTD it is even more important for you to ensure the proper office ergonomics and set up of your computer workstation in order to reduce further damage and injury.