Scaphoid kinematics before and after scaphotrapeziotrapezoidal ligament section. Assessment by radiostereometric...

The purpose of this study was to measure changes in scaphoid kinematics after division of scaphotrapeziotrapezoidal ligaments, with the intention of determining a clinical measure that could be detected by computed tomography. Twelve freshly frozen cadaver upper extremities were marked with tantalum beads and fixed in positions of neutral, 30° extension, and 40° ulnar deviation. Stereoradiographs for bone migration analysis by radiostereometric analysis and computed tomography scans for visible assessment were obtained before and after scaphotrapeziotrapezoidal ligament section. After ligament resection there was a scaphoid supination of 5° and a small (less than 1 mm) radial, distal, and dorsal translation of the distal pole in 30° of wrist extension. In computed tomography reconstructions, the ligament section appeared as a 1 to 2 mm gap in the scaphotrapeziotrapezoidal corner, with loss of articulation between the distal scaphoid pole and the trapezoid bone and increased scaphoid flexion.