Analysis of the Wrist Motion Using 3 / 대한정형외과학회잡지

ABSTRACT

The wrist joint is composed of midcarpal, radiocarpal and distal radioulnar joints. It is difficult to analyze the motion of these joints by the simple roentgenogram. We reconstructed three dimensional images of the wrist and distal radius from computerized tomogram using a new interactive graphics software written in Pascal and Turbo Graphic. There were 10 normal wrists in neutral position, and two normal and one abnormal wrists in ulnar-radial deviation and one normal wrist in flexion-extension were analyzed in this study. For simplification, the images were reformatted for the scaphoid, the proximal carpal row, the distal carpal row and the distal radius. We established the three dimensional references for wrist by defining the Z axis as the long axis of radius, the X axis as a line which is in horizontal plane and parallel to the anterior cortex of distal radius about 2 cm proximal to the articular surface and the Y axis as the automatically defined line perpendicular to both X and Z axes. We measured the angles between the X-axis and the reference lines of scaphoid and each carpal rows. The scaphoid was internally rotated by 60,0 degrees from X axis, the proximal carpal row by 7.0 degrees and the distal carpal row by 25.6 degrees each. There was only minimal change in the angles during the ulnar and radial deviation. The pattern of angles in abnormal wrist was different from those in normal wrists. In flexion-extension, the angle of distal carpal row was changed significantly, which means there was some error in selecting the reference line of distal carpal row as an axis of motion, or in measuring the angles, or it can be suggested that there is some rotational motion of distal carpal row on the Z axis. The proximal poles of the scaphoid and the triquetrum were displaced ventrally during flexion and dorsally during extension.