Anatomic Variation in Volar Tilt of the Scaphoid and Lunate Facet of the Distal Radius.

PURPOSE: The aim of distal radial fracture treatment is to achieve optimal function through the restoration of normal anatomy, including volar tilt. The accuracy of assessing volar tilt on standard lateral radiographs compared with anatomic tilt lateral (ATL) radiographs is uncertain. This study aimed to investigate the anatomy of the articular surface of the distal radius, in particular measuring the angle between the dorsal and volar rims at several points from radial to ulnar, to ascertain whether volar tilt is uniform between the scaphoid and lunate facet and to explore consistency between standard lateral and ATL views.

METHODS: We studied 38 dry cadaveric specimens of radii. The distal articular surface of each specimen was marked at 5 intervals and placed in a customized jig. A 1.5-mm stylus was placed at each marker to represent the articular surface angle, and was photographed in standard lateral and ATL projections. An on-screen protractor was used to measure each angle from the digital photographs.

RESULTS: The volar tilt measurements at the lunate facet demonstrated a significantly shallower angle than those at the scaphoid facet. The measurements between the standard lateral and ATL were found to have no significant difference.

CONCLUSIONS: Adjusting the projection angle between a simulated standard lateral and ATL view did not significantly change the volar tilt measurements in this anatomic study. The lunate facet was found to have a significantly shallower volar tilt than the scaphoid facet. Variance in radiographic volar tilt may relate to different anatomic sagittal planes, reflecting the anatomic variation between the scaphoid and lunate facets.

CLINICAL RELEVANCE: A detailed understanding of distal radius anatomy is required by the surgeon for accurate radiologic interpretation and anatomic fracture reduction and fixation.