Repetitive Stress Injury

I

Introduction

Repetitive Stress Injury (RSI), work-related physical symptoms caused by excessive and repetitive use of the upper body. Repetitive stress injuries typically occur when tasks are performed under difficult conditions, using awkward postures and poorly designed equipment. Common tasks that cause RSI include typing for hours on a computer keyboard, cutting meat, or working on a factory production line. Other terms used to describe RSI include cumulative trauma disorder, repetitive motion disorder, occupational overuse syndrome, and upper extremity musculoskeletal disorder.

The majority of RSI cases occur in industries such as manufacturing, assembly, and service. Fewer cases occur in clerical, sales, professional managerial, secretarial, and data-entry jobs. Musicians and dancers also have a high incidence of RSI, which has led to the creation of a medical specialty known as performing arts medicine.

Symptoms of RSI are varied, but they are roughly divided into three categories. Early signs include muscle aches and fatigue in the arms, wrists, or neck during work. These symptoms may begin slowly over weeks or months, but they usually disappear with rest. After several months, aching and fatigue persist for longer periods and beyond the workday, diminishing the ability to perform everyday tasks. Advanced symptoms include aching and fatigue while at rest, problems sleeping due to pain, and partial or total disability. As symptoms become more severe, other complications may develop, such as depression resulting from chronic pain.

II

RSI Injury

Injury from RSI primarily affects soft tissue, including muscles, tendons, ligaments, nerves, and connective tissue. These injuries tend to increase in severity over time. Once the chain of injury begins, RSI tends to progress unless the worker changes the factors that created the stress in the first place.

---

---

A

Muscle Injury

Muscles of the forearm do most of the work of moving the fingers and wrists. These small muscle groups are not designed for extended periods of contraction, so they are vulnerable to injury during repetitive work. Injury is even more likely to occur if the stronger muscles of the back, shoulder, and upper arm are impaired because of poor posture or poorly fitted office equipment, forcing the forearm and hand muscles to do more work. With overuse, forearm muscles contract too often, decreasing the blood and oxygen supply to the muscle. Lactic acid and other metabolic products build up in the muscle, causing fatigue and pain. The muscle contracts further in response to the pain.

B

Tendon Injury

The decreased blood supply to the muscles in the arms causes the tendons to tighten, which in turn limits wrist and finger range of motion. When tendons are continually tightened because of muscle injury and contraction, they can be injured by friction as they rub against ligaments or bone, causing the inflammation and pain known as tendinitis. As tendons change their angle (as when bending or straightening the wrist), they are kept in place by a variety of sheaths and pulleys similar to the guide rings on a fishing rod. Friction in these areas can cause inflammation and swelling of the sheath and tendon known as tenosynovitis. When this occurs at the base of the thumb, it is called DeQuervain’s disease.

	More from Encarta
	•  Important Notice: MSN Encarta to be discontinued. Learn more. •  Presidential Myths Quiz •  Coffee break: Recharge your brain