Intra-articular distal radius fractures involving the distal radioulnar joint (DRUJ): three dimensional computed tomography-based classification.

PURPOSE The purpose of this study was to analyze fracture patterns and the magnitude of displacement in the distal radioulnar joint (DRUJ), by three-dimensional (3D) computed tomography (CT), for distal radius fractures with intra-articular displacement of the radiocarpal joint. METHODS We reconstructed 3D images for 72 consecutive patients with displaced intra-articular distal radius fracture on the basis of fine-cut axial CT data. The fracture patterns involving the DRUJ were classified on the basis of the location and direction of fracture lines, and the extent of fracture comminution. We measured the maximum spatial distance of the gap and the step between the fragments in each 3D image, and the magnitudes of displacement between the groups were compared by analysis of variance followed by post-hoc analysis by use of Tukey's test. RESULTS Sixty wrists had a fracture involving the DRUJ. We classified the 60 wrists into 3 types of fracture pattern. Type 1 was a transverse fracture with minimum displacement. Type 2, in which fracture lines extended into the distal margin of the sigmoid notch, was the most common longitudinal fracture. Type 3 was a fracture with multiple fragments. The step and gap in Type 3 was significantly larger than that in the other types. CONCLUSIONS Eighty-three percent of intra-articular distal radius fractures had DRUJ involvement, and 28% of the wrists had multiple fragments. For Type 3 fractures with dorsal or proximal comminution displacement was significantly larger than for simple Type 1 and 2 fractures. Surgical intervention for the DRUJ fragment may be beneficial when there is remarkable intra-articular displacement.