Functional anatomy of the soft tissues of the hand and wrist: In vivo excursion measurement of the flexor pollicis longus-tendon using MRI

Magnetic resonance imaging (MRI) of the flexor pollicis longus-tendon (FPL-tendon) with the thumb in different positions allows the in vivo assessment of its abduction-adduction/flexion excursion. Measurements can also be performed in different positions of the wrist. In our study, the mean excursion amplitudes of the FPL-tendon in seven healthy volunteers were 2.6 (+/-0.26), 2.6 (+/-0.25), and 2.7 (+/-0.63) em for neutral position, ulnar, and radial deviation of the wrist, respectively. The contribution of the abduction-neutral position route and the neutral position-adduction/flexion route to the total excursion of the thumb varied for the different positions of the wrist, despite the equal excursion amplitudes. The possibility of visualization and the accurate determination of the FPL-tendon excursions is of use in the reconstruction and the transposition of the FPL-tendon. In addition, the shift of the FPL-tendon can be visualized for different positions of the thumb and the wrist.