Kinematics of Thumb Opposition

INTRODUCTION One of the most important hand functions is thumb opposition, which results from flexion, abduction and axial rotation at the carpometacarpal, metacarpophalangeal and interphalangeal joints [1]. The thenar muscles, innervated by the median nerve, are critical for coordinated thumb movements. It is commonly observed that thumb opposition is impaired with median neuropathy [2]. The clinical method to assess thumb motion capability is to measure the distance between the thumb tip and the fingertip, or between the thumb tip and distal palmar crease [3]. Goniometric measurement quantifies thumb range of motion in isolated planes, but does not provide information of the dynamic relationship between flexion and rotation. The purpose of this study was to examine the 3D movement of the thumb during opposition.