UE Tendon and Muscle Disorders
MSDs of the distal UE are prevalent in the working world and have substantial economic costs (Dale et al., 2013; Descatha, Leclerc, Chastang, & Roquelaure, 2003; Gerr et al., 2002; Silverstein et al., 2010; Tanaka, Petersen, & Cameron, 2001). These MSDs can affect each segment of the upper extremity, from the shoulder to the hand. Risk factors for wrist and hand MSDs include repetitive pushing, hand force, combined exposure to both force and repetition, sustained gripping (e.g., computer or hand tool use), repetitive redundant movement of the thumb and digits (e.g., typing or texting), sustained or repeated static loading of the weight of an instrument or tool, and use of vibrating tools (Barr, Barbe, & Clark, 2004; Fry, 1986; Gold, Mohamed, Ali, & Barbe, 2014; Gupta & Mahalanabis, 2006; Kakosy, Nemeth, Kiss, Laszloffy, & Kardos, 2006).
Hand‐intensive jobs that feature forceful and repetitive activities are associated with both the onset and severity of hand and wrist MSDs (Barr et al., 2004; Viikari‐Juntura & Silverstein, 1999). Other physical risk factors shown to exacerbate risk include adoption of non‐neutral wrist and forearm postures, sustained gripping, sustained or repeated static loading of the weight of an instrument or tool, high impact jolting, exposure to hand‐arm vibration (HAV), and exposure to cold temperatures (NIOSH, 1997; NRC‐IOM, 2001). Continuous movement of a joint into end of range, for example, with repeated hyperextension of metacarpophalangeal joints, may be another causative factor due to enhanced inflammation in joint and tendon tissues (Gold et al., 2014; Walsh, Delahunt, & McCarthy, 2011). Individuals with prolonged heavy or one‐sided hand workloads or increased high impact “jolting” of the hand show increased incidence of hand osteoarthritis, with higher incidence in females (Bernard, Wilder, Aluoch, & Leaverton, 2010; Blumenfeld et al., 2014; Rossignol et al., 2005). The following sections discuss some of the more common UE disorders, their characteristics, prevalence and incidence, anatomy and pathology, and risk factors.
Hand‐wrist tendinopathy
Description/characteristic features
Wrist tendinopathy is a broad term used to characterize disorders involving damage or irritation to tendons and/or their synovial sheaths located in and around the wrist joint. Such disorders comprise the most common complaints evaluated by hand care professionals (McCauliffe, 2010). These disorders were formerly characterized as wrist tendinitis; however, recent research has demonstrated that these disorders demonstrate relatively few inflammatory cells (McCauliffe, 2010). Instead, these tendon disorders often appear to be the result of a disruption in the structural integrity of the tendon. This has led some to prefer use of the term tendinosis (implying a breakdown in the collagen structure of a tendon) or the broader and more clinically used term tendinopathy (a term implying a general disease process of the tendon).
Wrist tendinopathy usually affects a single tendon, but in some cases, it involves two or more tendons. Symptoms may start with a mild pain that progressively worsens with continued activity. The pain often presents as diffuse, as opposed to a localized, and may extend up to the forearm or into the fingers. Pain may be variously described as a dull ache, a burning sensation, or a sharp stabbing pain. Symptoms may be so painful that they may result in significant adverse effects on the activities of daily living. Even common tasks such as turning doorknobs or lifting a coffee cup may prove painful. Symptoms more rarely observed include numbness, loss of motion, or pain at rest. Often, wrist tendinopathy occurs at points where the tendons cross each other or pass over a bony prominence. These are possible sites of irritation and can lead to discomfort when moving the wrist joint. De Quervain’s disease is often characterized by the development of pain on palpation, stiffness, and a decrease in strength capacity in the affected areas. Other similar conditions are trigger thumb and triggering of the middle and ring fingers, characterized by pain with motion of the affected tendon.
Epidemiology (prevalence/incidence)
MSDs involving the arm and hand account for only 5.1% of all work‐related MSDs (Bureau of Labor Statistics, 2018), and disorders of the hand and wrist constitute 40% and 13%, respectively, of such cases (Bureau of Labor Statistics, 2015). Hand complaints are common among manual workers with self‐reported prevalence generally around 30–45% (Thomsen et al., 2007). Symptoms are not always accompanied by clinical findings. Several studies found very low prevalence of wrist tendinopathy with swelling and/or crepitation but with a considerable variation—from no cases of clinical tenosynovitis at all, up to more than 18%, apparently with more or less the same case definition (Thomsen et al., 2007).
Tendinopathy cases of the hand and wrist (e.g., de Quervain’s tenosynovitis) or fingers (e.g., trigger finger) numbered 4,896 in 2001 (Bureau of Labor Statistics, 2001). Evaluation of the incidence of de Quervain’s disease among U.S. military personnel from 1998 through 2006 demonstrated that women had a significantly (p < 0.0001) higher rate of this disorder (2.8 cases per 1,000 person‐years) compared to men (0.6 cases per 1,000 person‐years). Other risk factors for de Quervain’s disease in this population included age greater than 40 and greater incidence among blacks (Wolf, Sturdivant, & Owens, 2009).
Figure 2.4 The site of de Quervain’s syndrome is encircled. APL: abductor pollicis longus; EPB: extensor pollicis brevis; EPL: extensor pollicis longus.
Anatomy/pathology
De Quervain’s disease is a specific wrist tendinopathy involving the entrapment of the tendons of the extensor pollicis brevis and abductor pollicis longus. Figure 2.4 illustrates the region associated with the development of de Quervain’s syndrome. Patients with de Quervain’s disease (as well as trigger finger) tend to exhibit a lack of inflammation in the affected region (Clarke, 1998; Sbernardori & Bandiera, 2007). Instead, there appears to be a breakdown of tissues of the gliding layer of the tendon sheath. Examination of tendons tends to reveal nodularity and tendon fraying, which is thought to be secondary to impingement by the damaged sheath. Both disorders often exhibit the development of fibrotic tissue. In the case of de Quervain’s syndrome, deposition of fibrotic tissue in the extensor retinaculum can be thickened up to five times greater than the thickness in control tissues (Clarke, 1998). Overall, signs point to a process of tissue degeneration as opposed to an inflammatory response, with the degeneration resulting from abnormal mechanical stress being imposed on the tendon and the tendon sheath (McCauliffe, 2010).
Risk factors/activities associated with hand‐wrist tendinopathy
Tendinopathy of the hand, wrist, and forearm has long been associated with performance of forceful and repetitive hand activities as potential causal factors (e.g., Armstrong, 1987). Studies assessing risk factors associated with hand‐wrist tendinopathy demonstrate that exposure to force, repetition, and non‐neutral postures all demonstrate positive associations; however, the combination of force and repetition demonstrate the strongest relationship with these hand‐wrist disorders (Armstrong, 1987; Barbe et al., 2013; Byström, Hall, Welander, & Kilbom, 1995; Kurrpa, Viikari‐Juntura, Kuosma, Huuskonen, & Kivi, 1991; Luopajärvi, Kuorinka, Virolainen, & Holmberg, 1979; Roto & Kivi, 1984). The study by Kurrpa et al. (1991) was prospective in nature and found that greater time on the job was associated with increased risk of hand‐wrist disorders, demonstrating temporality. Repetitive forceful activity of the thumb is often associated with the development of de Quervain’s syndrome (Freivalds, 2004).
Lateral tendinopathy of the elbow