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Designing for Hand and Wrist Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
Injuries to the median nerve at any of the compression sites (shown with dotted circles in Figure 7.10) affect motor function in the hand and wrist, and may affect sensory function in the hand. Carpal tunnel syndrome, a common problem, is caused by pressure on the median nerve within the carpal tunnel. It creates altered sensation in the distribution of the median nerve and decreased thenar muscle function—both significantly impair hand use. The carpal tunnel is filled with many structures—multiple tendons from the extrinsic flexor muscles in the forearm, their tendon sheaths, and the median nerve—tucked into this small space (Figure 7.11). Untreated, carpal tunnel syndrome can lead to permanent nerve damage. Overuse, rheumatoid arthritis with associated tendon and tendon sheath swelling, and cysts at the carpal joints can cause carpal tunnel syndrome (Drake et al., 2015, p. 798). Due to inflammation, the median nerve may become tethered within the carpal tunnel, causing another variation of carpal tunnel syndrome. Treatment for carpal tunnel syndrome may include medication, surgery, nerve gliding exercises, and/or activity modification. Braces or splints that limit palmar flexion of the hand and wrist may be used to position the wrist to decrease pressure on the median nerve.
Anthropometry and Biomechanics
Published in Nancy J. Stone, Chaparro Alex, Joseph R. Keebler, Barbara S. Chaparro, Daniel S. McConnell, Introduction to Human Factors, 2017
Nancy J. Stone, Chaparro Alex, Joseph R. Keebler, Barbara S. Chaparro, Daniel S. McConnell
We are all susceptible to this type of injury. When using our computer keyboards, our wrists often have both dorsiflexion and ulnar deviation. In addition, keyboarding requires repetitive motions, which increases the chance for carpal tunnel syndrome. Carpal tunnel syndrome involves more than inflamed tendons, but also compression damage to the median nerve that goes through the wrist’s carpal tunnel (Eleftheriou et al., 2012). An individual who suffers from carpal tunnel syndrome might experience tingling or prickly feelings, numbness, an inability to grasp, and other losses of hand functions (Johnson, 1985). With the use of wrist rests and an ergonomically designed keyboard, it is possible to place the hands in their neutral position, reducing the chance of injury.
Minimize repetitive motion
Published in Michael Wiklund, Kimmy Ansems, Rachel Aronchick, Cory Costantino, Alix Dorfman, Brenda van Geel, Jonathan Kendler, Valerie Ng, Ruben Post, Jon Tilliss, Designing for Safe Use, 2019
Michael Wiklund, Kimmy Ansems, Rachel Aronchick, Cory Costantino, Alix Dorfman, Brenda van Geel, Jonathan Kendler, Valerie Ng, Ruben Post
Perhaps the most well-known problem is carpal tunnel syndrome, affecting the wrists where the median nerve passes through a small anatomical structure called the carpal tunnel. In addition to intense pain, carpal tunnel syndrome symptoms include finger tingling and numbness, reduced range of hand and finger motion, and reduced ability to apply force with the hand.1
Prevalence and risk factors for self-reported symptoms of carpal tunnel syndrome among hospital office workers: a cross-sectional study
Published in International Journal of Occupational Safety and Ergonomics, 2023
Carpal tunnel syndrome (CTS) occurs as a result of compression of the median nerve in the carpal tunnel at the wrist joint level and is the most common peripheral nerve entrapment disease. CTS is not a simple condition but a serious cause of disability, and is defined as the upper extremity musculoskeletal disease associated with the highest cost among working-age patients in relation to taking sick leave, decreased productivity and personal financial losses [1]. The US Bureau of Labor Statistics reported that all musculoskeletal problems were responsible for an estimated 32.2 cases and an average 12 days off work per 10,000 workers in 2015, in all industries in the USA, while CTS accounted for the highest number of workdays lost (on average, 28 days off work per case) [2]. Early detection of CTS can also be a critical factor affecting the return to work. Workers with a correct and early diagnosis of CTS were found to be much more likely to return to work than workers diagnosed weeks or months later [3].
Women’s wrist and elbow at work: analysis of acute injuries and cumulative trauma disorders to improve ergonomics in female-dominated activities
Published in Ergonomics, 2022
Silvana Salerno, Claudia Giliberti
Many occupations, where the presence of women is predominant, require repetitive movements, often a cause of upper limb occupational disorders, such as epicondylitis, carpal tunnel syndrome, rotator cuff syndrome, supraspinatus tendinopathy, etc. (Bergamasco, Girola, and Colombini 1998; Nordander et al. 2009; Chen et al. 2010; Bonfiglioli, Mattioli, and Violante 2015; Major, Clabault, and Wild 2021). Most studies, involving cases where women were compensated for work-related disorders, concern carpal tunnel syndrome (CTS) and epicondylitis (Lippel 2003; Probst and Salerno 2016). Carpal tunnel syndrome (CTS) refers to the compression of median nerve at the carpal tunnel of the wrist. In most cases, pain, numbness and tingling may extend from the hand up to the arm. Weak grip strength and weakness of the muscles, at the base of the thumb, may persist for a long time. Epicondylitis is another common upper-extremity musculoskeletal disorder among women, especially in the age group 40–60. It involves tendinopathy in which the outer (lateral epicondylitis) or the inside part of the elbow (medial epicondylitis) becomes painful and swollen. In the general population, the prevalence of lateral epicondylitis is higher than medial epicondylitis and both are more frequent among women, as confirmed in medical consultations (Shiri and Viikari-Juntura 2011; Lee et al. 2016). Pain may extend into the back of the forearm and grip strength may also be weakened, determining an impaired function.
Cross-sectional changes of the distal carpal tunnel with simulated carpal bone rotation
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Carpal tunnel syndrome is a peripheral nerve entrapment syndrome affecting a large portion of the general (Atroshi et al. 1999) and working populations (Dale et al. 2013; Luckhaupt et al. 2013). The most common treatment for carpal tunnel syndrome is to undergo carpal tunnel release surgery, whereby pressure at the median nerve is relieved by transecting the transverse carpal ligament (TCL) (Badger et al. 2008; Rodner and Katarincic 2008). Regarding various patient outcome measurables, surgical treatment shows preferred results, as compared to those for therapeutic options such as splinting (Gerritsen et al. 2002), non-steroidal anti-inflammatory drugs (Jarvik et al. 2009) and steroid injections (Hui et al. 2005). Although surgery is more effective, the invasive nature of the procedure does present the risk of complications, albeit rare (Karl et al. 2016). Such risks are minimal with noninvasive physical therapeutics. These options, which can include splinting (Huisstede et al. 2010) and carpal bone mobilization (Huisstede et al. 2010), often involve force application at or near the radiocarpal or midcarpal joint. These force applications are likely to induce relative motion of the carpal bones.