RESUMO
INTRODUCTION: This study applied mathematical modeling to examine the anatomy of the distal radius; to define the radiographic parameters in a 3D imaging modality; and to report their normal ranges in the uninjured radius. MATERIALS AND METHODS: A series of 50 cone-beam computed tomography (CBCT) scans of uninjured radii were analyzed using computer-aided image processing. The radius shape model was used to determine the optimal location for measuring the longitudinal axis. With the axis determined, the volar tilt and radial inclination angles and the areas of the articular facets and their reference points were analyzed. RESULTS: The optimal location for determining the longitudinal axis was between 28.8 and 53.3 mm proximally from the articular surface. The mean radial inclination angle was 21.8°. The mean volar tilt angle via the most distal tips of the volar and dorsal rims was 13.0°; along the lunate and scaphoid facets it was 9.1° and 11.2°, respectively. The scaphoid facet was larger than the lunate facet and 25% of it was convex. CONCLUSIONS: Computer-aided CBCT image processing offers an advanced tool to record 3D geometry and the radiographic parameters of the osseous structures of the wrist. Analysis of the distal radius' anatomy showed that the longitudinal axis was affected by its measurement location and subsequently also affected the determination of the angular parameters. We also report the variation of the volar tilt along the articular surface and the shapes and sizes of the articular facets.