Tendinopathy in the workplace

Abstract

Until relatively recently, little attention has been paid to the millions of workers who go to work each day and perform the same highly repetitive tasks for years at a time. An assembly line worker may repeat the same task 25,000 times per day [1]. Each exertion requires a specific movement of the upper or lower extremity, usually with the maintenance of a static posture of the trunk, head, and neck. Over time, the amount of physical effort required to accomplish such seemingly mundane tasks is extraordinary. With millions of people at computer keyboards each day, it is not surprising that overuse syndromes or repetitive strain injuries have come into media focus and attention. Repetitive strain injuries are disruptions of muscles, tendons, bone, or nervous system precipitated or exacerbated by repeated forceful exertions, awkward posture sustained for a long time, surface contact stresses, vibration, or cold. Jobs that have multiple risk factors have a greater likelihood of causing or contributing to musculoskeletal disorders depending on the magnitude, duration, and frequency of the exposure to each risk factor [2]. Patients with upper extremity repetitive strain injuries present with pain, usually in the neck, shoulder, arm, or hand; fatigue, either generalized or localized; and weakness, paraesthesias, loss of dexterity, depression, and loss of sleep. Many patients relate this to the duration and intensity of their work. Symptoms may develop over weeks, months, or years, and patients commonly cannot pinpoint a specific time of onset. Symptoms may be poorly localized, nonspecific, and episodic, and the causes may be multifactorial.These patients may initially appear to suffer from simple fatigue. The difference between simple fatigue and repetitive strain is related to the duration and intensity of the symptoms. Fatigue can occur after a work shift and is short lived. With repetitive strain injuries (RSI), recovery between work shifts does not occur, and patients begin their day or week with pain [3]. The Occupational Safety and Health Administration (OSHA) has defined several conditions as "work-related musculoskeletal disorders" (WMSDs) caused by workplace stressors [4].These include carpal tunnel syndrome, rotator cuff tendinopathy, de Quervain's disease, trigger finger, and lateral and medial epicondylitis. The term tendinopathy denotes pain involving tendons or their surrounding structures, which at times can be inflamed, usually caused by repeated or forceful exertion by the affected part.Tendinopathy is usually made worse by performing an activity in an awkward position. These conditions have now been recognized as the leading chronic work-related musculoskeletal disorders, and have served as the basis for the proposed ergonomic standard that will be discussed later. This chapter examines the epidemiology of these problems and the cost to society as a whole. Newer evidence for work relatedness and occupational tendon pathophysiology will be discussed, and we shall also discuss how ergonomics relates to the correction and prevention of these issues, focusing specifically on tendinopathy. There is much controversy about the cost-effectiveness of ergonomic programs. Follow-up evidence for cost effectiveness will be presented.