Distal Radius Volar Shear Fractures: A Computed Tomography Characterization and Analysis

PURPOSE: To characterize volar shear fractures of the distal radius using computed tomography (CT) imaging to better evaluate dorsal cortical fracture involvement, articular complexity, and morphologic features to assist in operative planning. METHODS: A retrospective review of patients with CT-confirmed distal radius fractures was performed. One hundred ten volar shear fractures were identified and classified according to the AO/Orthopedic Trauma Association system, with CT-based characterization guided by previously described morphologic patterns. Volar shear B1 fractures were defined as partial articular fractures primarily involving the radial styloid process and volar shear B3 fractures as partial volar articular fractures without dorsal fracture lines. Fractures demonstrating partial volar articular involvement with dorsal fracture extensions were descriptively referred to as transitional-B3 fractures. Volar shear type C fractures were defined as complete articular fractures involving the volar articular margin. Demographic data, fracture characteristics, and morphologic features were compared across fracture types. RESULTS: Dorsal cortical fractures were present in 70% of volar shear fractures. Computed tomography imaging led to reclassification in 44% of fractures initially diagnosed as B3, and 28% of those diagnosed as transitional-B3. Type C fractures demonstrated greater fracture fragmentation, higher rates of longitudinal splits, and more frequent central articular depression compared with the other types. Dorsal impaction was identified in 78% of transitional-B3 fractures and 100% of type C fractures. Type B1 fractures exhibited shorter maximal volar cortical length and less available cortex for fixation compared to the others. Volar lunate translation and greater lunate subsidence were most commonly observed in type C fractures. CONCLUSIONS: Dorsal cortical extensions are prevalent in volar shear fractures and may have articular complexity that is not fully appreciated on radiographs alone. CLINICAL RELEVANCE: Computed tomography imaging provides additional detail for accurate diagnosis and reveals fracture morphologic patterns that should prompt consideration of comprehensive fixation strategies depending on the specific fracture type.