Cumulative trauma disorder

Responding is Amy Hamilton, safety technical product support specialist, Grainger, Lake Forest, IL.

A cumulative trauma disorder, also known as CTD, is defined as the excessive wear and tear on tendons, muscles and sensitive nerve tissue caused by continuous use over an extended period of time. CTDs can develop from improper work positioning, repetition or force.

Millions of Americans work in front of computers every day. While this may not seem like a task that would expose employees to potential injury on the job, improperly designed workstations do pose ergonomic concerns. Ergonomics is the science of fitting workplace conditions and job demands to the capabilities of the working population.

The three main risk factors found in computer workstation environments that can lead to CTDs are:

• Awkward posture and position such as bent wrists, elbows held away from the body, outstretched arms or slumped shoulders
• Repetitive action from typing, keying and sorting operations
• Use of excessive force when typing

These risk factors can be controlled by adjusting the workstation, varying worker position, reducing continuous or repetitious actions, and periodically stretching throughout the day. Employers should design workstations to reduce or eliminate bad ergonomic exposures. A neutral work position can be obtained by adjusting the worker’s desk and chair height, as well as keyboard position.

Key elements to consider for an ergonomic computer workstation include:

• Invest in a good chair that can be adjusted several ways. The seat height should be set so that thighs are nearly parallel with the floor and feet rest flat on the floor. The chair back should adjust and provide lumbar support.
• Make sure a monitor’s casing is 2-3 inches above eye level, centered and approximately 18-30 inches from the face.
• Take steps to reduce glare on the screen.
• Use a document holder next to the computer screen. Place it at the same height and distance from the worker’s face as the screen.
• Keep wrists flat and straight in relation to the forearms and centered to the body when using a keyboard and mouse.
• Relax the arms and elbows, keeping them close to the body.
• Place adjustable keyboards so they form an approximate 90-degree angle at the elbow.
• Take frequent and short breaks to stretch the hands and fingers and to rest the eyes. Try to focus on an object several feet away. Move eyes in all directions.
• Position work equipment so the most-frequently used items are within comfortable reach.
• Use a telephone headset to free up hands and prevent cradling of the phone.

The appropriate placement of the components and accessories for a computer workstation will allow workers to maintain neutral body positions, perform more efficiently and work more comfortably. Although no single “correct” posture or arrangement of components will fit everyone, basic ergonomic design initiatives can improve workers’ ergonomic positioning to help eliminate or lessen the potential for CTDs.

Editor’s Note: This article represents the independent views of the author and should not be construed as a National Safety Council endorsement.