The in vivo study of three-dimensional kinematics of fractured scaphoid

Abstract

Objective To accurately quantify three-dimensional in vivo kinematics of fractured scaphoid in wrist flexion-extension and radial-ulrar deviation, and to provide the theoretic bases for clinical application. Methods The bilateral wrists of 10 adult volunteers with scaphoid fractures were imaged by spiral CT at neutral position, at 15°, 30°, 45° and 60° of wrist flexion-extension, at 10° and 20° of radial deviation and at 10°, 20°, 30° and 40° of ulnar deviation. The 3D quantitative measurement and analysis of fractured scaphoid were performed in our computer-operated simulation system. The 3D kinematic data of the proximal and distal fragments of the fractured scaphoid were measured using the center of articular surface of the distal radius as reference. The kinematic data from the healthy side scaphoid were also acquired for comparison. Results After the scaphoid was fractured, being compared with the normal scaphoid, the proximal fragment of the scaphoid did not show obvious changes of rotation and translation. The changes of the distal fragment of the scaphoid were significant. When the wrist was positioned at 10° radial deviation and 30° extension, the distance between the centroids of distal and proximal fragment models was the smallest. Conclusion In the treatment of scaphoid fractures, the wrist should be kept at 10° radial deviation and 30° extension to ensure shortest distance between the fracture fragments and hence satisfactoiy reduction. The study provided some theoretic and technical reference for treatment of scaphoid fractures. Key words: Scaphoid bone; Fractures; bone; Imaging; three-dimensional; Kinematics; In vivo