ABSTRACT
<p><b>OBJECTIVE</b>To measure the axial rotation angles of the carpometacarpal joints during the digital opposition of thumb-index finger, thumb-medial finger, thumb-ring finger, thumb-little finger and the thumb's maximal opposition, then the application of these parameters were studied.</p><p><b>METHODS</b>Twenty neutrality-occupation volunteers (female 10, male 10) with no history of hand injuries or related diseases were involved in the study. First, all the markers' 3-D coordinates were obstained using the 3D motion analysis system (EVaRT4.1) during the digital opposition movements of thumb. Then, the axial rotation angles were calculated.</p><p><b>RESULTS</b>The average rotation angles of carpometacarpal joints during all kinds of digital oppositions were 29.1 degrees +/- 9.4 degrees (male), 24.8 degrees +/- 10.2 degrees (female), while the maximal rotation angles are: 35.3 degrees (male), 28.8 degrees (female).</p><p><b>CONCLUSIONS</b>The combination of video-based 3-D analysis system and mathematics make it possible to measure the axial rotation angles of thumb in vivo, as a result, the rotation angles of thumb carpometacarpal joints are measured precisely for the first time. These results can provide a few parameters for treatment and rehabilitation of carpometacarpal arthrositis.</p>