The three-dimensional analysis of three thumb joints coordination in activities of daily living

Presently, the angular movements of the three thumb joints during activities of daily living are limited as a result of their static position and lack of the required thumb range of motion information during motion. The purpose of this study was to investigate the three thumb joints' motion required in activities of daily living.

Sixteen healthy subjects were recruited for this study. A three-dimensional motion analysis system was used, with 14 retroreflective markers attached to each subject's thumb for motion data collection. Three joints including interphalangeal joint, metacarpophalangeal joint and carpometacarpal joint of the thumb were analyzed. The distal segment orientation relative to the proximal segment was defined the joint angle. The styloid process of radial bone orientation when quantifying the carpometacarpal joint movement was indirectly calculated from the third metacarpal bone.

The results showed that each type of activity involved significant interphalangeal flexion. The metacarpophalangeal joint mainly showed abduction motion, cylinder grip and spherical grip with the largest angle. For the carpometacarpal joint, the cylinder grip and spherical grip showed a relatively larger rotational range of motion. The interphalangeal joint in the three thumb joints was primary in flexion.

These results may provide more information to precisely describe the thumb function in daily life activities and also provide a reference when assessing thumb impairment or for constructing an index used for evaluating the recovery of an injured thumb in clinic. It also could help in designing hand-related instruments for use in activities of daily life.