Three-dimensional carpal kinematics in vivo

Objective. The purpose of this study was to accurately quantify three-dimensional in vivo kinematics of all carpal bones in flexion and extension and radial and ulnar deviation. Design and methods. The right wrists of 11 healthy volunteers were imaged by spiral CT with rotational increments of 5° during ulnar-radial deviation and of five of them also during flexion-extension motion. One regular-dose scan was used and the subsequent scans during wrist motion were performed with one-tenth of the regular dose. A three-dimensional matching technique using the internal structure of the bones was developed to trace the relative translations and rotations of the carpal bones very accurately. Results. Most of our results are in concordance with previously published in vitro data. We could, among others, substantiate proof to the statement that there is more than one kinematic pattern of the scaphoid. Furthermore, we could accurately describe small adaptive intercarpal motions in vivo of the distal carpal row. Conclusions. To our knowledge, this is the first time the three-dimensional in vivo kinematics of all eight carpal bones is quantified accurately and non-invasively.