The wrist joint is one of the most complex joints in the joint of the human body, composed of midcarpal, ardiocarpal and distal radioulnar joints, therefore, it is difficult to analyze the motion of these joints by the simple roentgenogram.
We reconstructed 3-Dimensional images of the wrist & distal radius from computerized tomogram using a redeveloped interactive graphics software written in Pascal and Turbo Graphic. Six mormal wrist in flexion-extension were analyzed in this
study.
For simplication, the images were reformatted for the lunate, scaphoid & triquetrum. We reestablished 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 horzontal plane &
parallel to the anterior cortex of the distal radius about 2cm proximal to the articular surface and the Y axis as the automatically defined line perpendicular to both X and Z axis. We measured the angles between the X-axis and the reference
lines
of
the scaphoid, lunate and triquetrum.
In the lateral view, the lunate was extended in 4 cases and flexed in 1 cases at the neutral position. The capitate was extended in 1 cases and flexed in 4 cases.
In the axial view, the lunate was internally tilted as 72.2%, the scaphoid internally tilted 55.3° and the triquetrum externally tilted 76.3°.
During the movement from full radial deviation to full ulnar deviation, the lunate was internally rotated from 83.3° to 69°. During the movement from full extension to full flexion, the lunate was externally rotated from 85° to 44°.
During the movement from full radial deviation to full ulnar deviation, the Scaphoid was internally rotated from 65° to 50.3°. The triquetrum was externally rotated from 95° to 74°.
We concluded three column theory was better method than the row theory for the interpretation of the kinetics of the wrist joint.
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