LAUSR

OBJECTIVES To characterize the location and frequency of the fracture lines and comminution zones of both-column fractures using fracture mapping. METHODS Both-column fractures were retrospectively reviewed in four Level-I trauma centers. Mimics software was used to reconstruct the both-column fractures and simulate the fracture reduction. Then, the fracture lines and the intra- and extra-articular comminution zones were drawn on a 3-D innominate bone template. The distribution of fracture lines and fracture fragments were also be mapped on the 2-D template of the acetabulum. All the included patients were divided into low- and high-variety group according to the anterior column fracture line above or below the anterior superior spine. The anatomical characteristics of the posterior wall fragment were also analyzed in these two groups. RESULTS Seventy-eight both-column fracture patients were included. The "T" type or inverted "Y" type main fracture lines divided the innominate bone into low-variety (n=11) and high-variety (n=67) both-column fractures. The extra-articular comminution zones are usually distributed between the posterior iliac fragment and anterior column fragment. High-variety-type both-column fractures are usually combined with "high" and "sharp" posterior wall fragments, while low-variety-type both-column fractures are usually accompanied by "low" and "flat" posterior wall fragments. The comminution zones in the acetabulum are mostly concentrated in the anterior and inferior parts of the acetabulum. CONCLUSIONS The innominate bone is divided into three major parts in the both-column fracture, and the fracture center is located at the proximal of the acetabular dome. The both-column fractures are divided into low- and high-variety patterns. The location of the anterior column fracture determined the characteristics of the posterior wall fragment.