Investigation of low-force high-frequency activities on the development of carpal-tunnel syndrome

The objective of this study was to determine the effects of repetitive motion on the flexor tendons and synovium in the carpal tunnel. One possible mechanism of tendon damage is fraying of the tendons as they slide past each other in the carpal tunnel. Increases in tendon friction were measured in human cadaver arms. The flexor tendons were loaded using pneumatic cylinders while load cells were used to measure tendon force both distal and proximal to the carpal tunnel. Results showed that tendon force distal to the carpal tunnel decreased by over 10% after 6 h, while tendon force proximal to the carpal tunnel remained constant. Two rhesus monkeys were used to further study the effects of repetitive motion. One arm of each animal was subjected to 729000 repetitive cycles over a 3-week period. Results of the animal study showed that highly repetitive motions encountered over a relatively short period of time had little effect on the tissue in and around the carpal tunnel.