Article: Nerve Compression Injuries from Computer Use (published ADVANCE for Rehabilitation Directors March 2009)
Computers have saturated the American workplace. Approximately seven out of 10 United States workers use a computer every day for their jobs. That estimate doesn’t even include the number of people who use computers for recreation, personal matters and social networking. In the end, most people spend a significant part of the day typing and using a mouse.
From an ergonomic perspective, computer postures are often less than ideal. Long durations of slouched positions, squeezed shoulders, extended wrists and eye strain can take a toll. Adopting inappropriate computer postures can aggravate other injuries or conditions. Inquiring about a patient’s work status and job demands can often provide clues into chronic pain and overuse conditions, even if your patient holds a job that others might consider low-risk.
While sedentary office environments are relatively safe from traumatic injuries and trip-and-fall hazards, they’re not immune to worker injuries. Sedentary workers face a unique set of injury risk factors, and damage caused by computer use can be costly to treat. Some injuries may never resolve. Ergonomic professionals can help stem the tide of musculoskeletal overuse injuries by providing manageable, low-cost solutions to employees and workplace managers to safeguard the health of the white-collar workforce. These solutions focus on preventing common cumulative trauma disorders that arise in those who use computers for long intervals.
Those disorders include:
Cubital tunnel syndrome. Pressure on the ulnar nerve at the elbow can disturb nerve function and lead to numbness, tingling, and pain in the elbows, forearms and hands. Computer users who repeatedly lean on their arms can irritate this nerve, particularly if the elbows remain bent for sustained times. Sometimes the connective tissue over the nerve becomes thicker, or variations of the muscle structure over the nerve cause pressure.
Carpal tunnel syndrome. In effect, carpal tunnel syndrome (CTS) is a pinched nerve at the wrist. When pressure in the wrist builds from swelling, trauma or arthritis, the median nerve becomes pinched as it passes through the bony carpal tunnel. Symptoms may include numbness, tingling, and pain in the arm, hand and fingers. ( Read more on CTS here )
Neck and shoulder pain. According to research at Emory University published in the American Journal of Industrial Medicine, more than half of computer users each year develop neck or shoulder symptoms, and over one-third develop impairment or lose function.
Related disorders. Back pain, fibromyalgia, headaches, sprains, strains, de Quervain’s tendinitis, trigger finger and ganglion cysts may not be as common in computer operators as the overuse conditions described above, but they’re also seen in this population. (Read more on Cumulative Trauma Disorders here)
Computer Related Eye strain. Eye strain is the most common ergonomic-related problem among computer users. Symptoms include visual fatigue, blurred or double vision, burning and watering eyes, headaches and changes to eyeglass prescription. These complications are often grouped under the name computer vision syndrome (CVS). CVS results from refocusing on characters and images on the computer screen, and can be complicated by frequent changes between the screen and distant objects. Also, computer users blink an average of just 4 times per minute, compared to the natural rate of 22 per minute. This leads to dry eyes and sensations of itching, burning, blurring, heavy eyelids and double vision. (read more about computer eye problems and CVS here)
While there’s no evidence that computer use leads to permanent eye damage, temporary discomfort can be troublesome and reduce job performance. Therapists don’t treat eye conditions directly, but computer eye strain can translate into physical problems, body stress, general fatigue and muscle strain from inappropriate postures.
Simple suggestions can help, such as periodically focusing on objects at various distances, keeping office air moist through plants or a humidifier, adjusting a monitor so the top is even with eye level and adjusting monitor brightness and contrast. Computer workers should undergo regular eye testing at least once every 2 years, more frequently if symptoms arise, and consult an optician regarding special lenses or bifocals.
SETTING UP A WORKSPACE
How can ergonomics professionals minimize the occurrence of potential physical problems? Appropriate workspace principles and postural education are essential. Common setup mistakes force workers into awkward postures, repetitive tasks, forceful movements, continuous static positions without breaks, inadequate back and leg support, poor lighting, and improper positioning of documents, a monitor, keyboard and mouse pad. Focus on solving problems in these areas. (Review Industry Ergonomic Standards and Guidelines here)
Chair and keyboard position. Adjust the height of the chair so the upper thighs are parallel to the floor. Adjust the back support so the back is firmly supported and angled slightly backward, while the feet are supported on the floor or footrest. Workers shouldn’t cross their legs for any length of time. The height of the keyboard and mouse should keep the hands, wrists and forearms on the same plane. An adjustable keyboard tray can keep elbows and arms comfortably at the user’s side. Some ergonomic experts suggest a negative 1 to 2-inch decline tilt from the front of the keyboard to the back. (Read more about Ergonomic Guidelines for Seating here and read more about Ergonomic Guidelines for Keyboard Positions here)
The shoulders should be relaxed, with the elbows close to the body at a 90-degree angle at the shoulders and hands. Support the palms and wrists during typing, and avoid excessive direct contact to the wrists. Gel wrist rests are one solution.
Pay attention to the computer mouse design and computer mouse features. Poor mouse design can cause hand, wrist and arm pain. The mouse should fit the size of a user’s hand and promote neutral posture. Multi-size mouse models can accommodate people with large or small hands. (read more on Computer Mouse Designs and " How to Choose an Ergonomic Computer Mouse" here)
Monitor position. The human head weighs about 10 pounds, or the weight of a bowling ball. Studies show that for every centimeter of forward head and neck posture, strain on the neck muscles and ligaments triples. Computer users shouldn’t look up or down at the monitor. The top of the screen should be even with the user’s forehead and directly in front, at arms’ length. The user’s eyes should look slightly downward at approximately 15 to 30 degrees. If the person uses bifocals, lower the monitor below eye level and tilt the screen back 30 to 45 degrees. Monitor arms can help with the adjustability. (read more about Monitor Position Ergonomic Guidelines here)
Accessory positions. Frequent phone users should acquire a head set, and never hold the phone between the head and shoulder. Adjustable document holders keep reading materials at the same distance and level as the screen. Based on frequency of use, arrange objects into three reaching zones: primary (keyboard, computer mouse), secondary (phone, calculator, stapler) and tertiary (pictures, calculator). (Read more on Optimizing Your Reaching Zones here)
Computer Lighting. Some computer users hide their computer behind glare screens or block overhead light by slouching over their work. This forces them to lean closer to documents and adopt damaging postures. Ensure proper lighting by using a task lighting fixture, and avoid strong overhead light sources. Document holders can keep the screen and documents at the same distance from the eyes. (Read more on Computer Lighting Ergonomic Guidelines here)
Rest breaks. Even the most ergonomically designed workspace can’t prevent muscle fatigue and related complications. Muscles are meant to move, not to hold static positions for too long. Recommend 3-minute breaks every 30 minutes. During breaks, workers should breathe deep through the abdomen, relax the arms and stand to stretch the neck and shoulders. Periodically adjust the chair, stretch muscles, rest the eyes, drink plenty of water and change positions to avoid fatigue. (read more tips on how to reduce pain and improve posture here)
LOWDOWN ON LAPTOPS:Laptop Accessories
Laptop computers are becoming a necessary evil in the modern--and sometimes remote--business environment. Laptops are convenient, but they’re an ergonomic debacle. The flat-plane keyboard eliminates the ability to separate, tilt, tent or replace the positions of the keys and keypads. There’s virtually no adjustability to improve the position of the shoulders, elbows, wrists and hands. If an employee uses a laptop for extended sessions, you should make recommendations that can reduce discomfort. A laptop holder or stand is the top choice for better laptop ergonomics. Place the screen at eye level and angle it for easy viewing without bending or rotating the neck. Place the screen at arm’s length.
An external compact keyboard on an adjustable tray can help keep wrists neutral and elbows at a 90-degree position. Recommend a large screen (at least 15 inches), which minimizes the need to slouch and strain, and increase font size. An external mouse on an adjustable-position platform is more ergonomically friendly than the constrictive touch screen or track ball on the laptop.
For the position, users should recline the body with the screen angled slightly upward to minimize neck strain. The best chair is a fully adjustable office chair with lumbar support. A footrest can raise the hips slightly higher than the knees for a comfortable supported posture. Aim for neutral wrist posture through gel wrist rests and maintain the rule of three primary reaching zones.
Rest breaks are even more important for laptop users. At a minimum, operators should take their eyes off the screen and focus on a distant object, and perform simple stretches for the neck, shoulders, arms and legs. Remind users to separate from a laptop and walk around every few hours. (Read more on Laptop Ergonomic Guidelines here)
If carrying a laptop while traveling, carry the bag across the back in a messenger style, or use dual-padded shoulder straps. Rolling carriers are best for components over 10 pounds.
Computer-related ergonomics problems are omnipresent and injury rates are rising. Simple corrections can often make a significant impact on this troubling trend.
About the Author:
Nicole Matoushek, MPH, PT, is an ergonomics professional in industrial medicine, physical therapy and clinical management education based in St. Petersburg, Fla. and owns ErgoRehab, Inc. She can be reached at www.ErgoRehabInc.com or email: Inquire@ergorehabinc.com