MULTIPLANAR AND 3D CT OF ACETABULAR FRACTURES

Purpose: To establish a standard protocol for the multiplanar (MPR) an d 3D shaded surface display (SSD) reconstruction of CT data on acetabu lar fractures, and to assess the usefulness of these reformats. Materi al and Methods: Acetabular fractures in 15 patients were imaged by mea ns of plain radiographs, transaxial CT, MPR reformats, and SSD reforma ts. Results: The classification of the acetabular fracture was revised in 7/15 cases when the transaxial CT images were read after the plain radiographs. Although the MPR and SSD reformats did not alter the cla ssification, they did add to the degree of confidence in the diagnosis in 9/15 cases. In 2 patients, the MPR and SSD reformats indicated ope rative instead of conservative treatment. In the MPR reformats, the fo llowing views were considered essential in all cases: (a) along the an terior column; (b) along the posterior column; and (c) along both colu mns and the inferior ramus. In the SSD reformats, the following views were considered essential in all cases: (d) the latero-caudal en face view into the acetabulum; and 180 degrees opposite to this, (e) the me dio-cranial view (facing the quadrilateral plate). In 10/15 cases, the se views were all that was needed for classification. It was, however, essential to remove the femur from the images before reconstructing t he SSD views. Conclusion. Complex acetabular fractures with displaceme nt should-be evaluated by means of transaxial CT and additional MPR an d SSD reformats. The use of appropriate standard MPR and SSD views sho rtens the time required to produce the reformats and thereby maximizes the benefit gained.