MRI Evaluation of Finger Flexor Trajectories as They Enter, Pass Through and Exit the Carpal Tunnel as a Function of Forearm Rotation and Wrist Radial and Ulnar Deviation

Tendon displacement within the carpal tunnel has been suggested as a mechanism for wrist work-related musculoskeletal disorders. Tendon displacement has been examined during wrist flexion/extension, and forearm pronation/supination. The effects of radial/ulnar deviation, and how they interact with forearm rotation remain undocumented. The purpose of this study was to quantify linear and angular displacement of the finger flexor tendons during wrist radial/ulnar deviation in combination with forearm pronation/supination. The right distal forearms and wrists of 4 participants were scanned using magnetic resonance imaging. Analysis of the images enabled the measurement of linear and angular displacement. Tendons were displaced radially during radial deviation and pronation, and ulnarly during ulnar deviation and supination. The tendons were displaced furthest during radial-pronation and ulnar-supination. These findings support the results of previous researchers who found increased discomfort and median nerve contact pressure in these postures. These data further our understanding of potential mechanisms of injury.