Cumulative Trauma Disorder: Skeletal Muscle Dysfunction, 2000-2005

摘要

Chronic pain originating from the musculoskeletal system is a dominant cause of sickleave in modern industry and often a very disabling and troublesome condition for the individual. Although the cause of this problem in skeletal muscle is unknown, one of the most frequent situations in which muscle pain is experienced is in industrial workers who have to move repeatedly and/or forcibly. The cumulative trauma disorder (CTD) which results from repetitive movements is of special interest because these repeat-motion injuries are one of the most difficult to anticipate and prevent. Our studies in humans have shown that exposure to a single bout of repeated strains at moderate can lead to myofiber and fascial rupture without bleeding but accompanied by muscle pain, restricted motion, and loss of strength and power. Little is known about the effect of repeated strains on muscles or the dynamic components of repeated use such as velocity and acceleration which produce injury resulting in CTD or CTD risk. Since variations in human exposure and response, together with the necessity for repeated tissue sampling, make man unsuitable as a research subject, we have developed a rat model of repeated strain injury (CTD). The remarkable similarity of our injured rat muscles and the extensor carpi radialis brevis taken from humans with long standing lateral epicondylitis requiring surgery (Appendix 1)(8) provides support for the rat as a good research model and muscles as important tissues in the development of pain and dysfunction. Since the extensor carpi radialis brevis is also very susceptible to strain injury (7), we believe that more studies using our chronic strain injury protocol in rats wil reveal why repeated strain injury results in pain at the attachment sites of human muscles.