RAPID PROTOTYPING (STEREOLITHOGRAPHY) IN THE MANAGEMENT OF INTRAARTICULAR CALCANEAL FRACTURES

The purpose of this study was to evaluate and compare the diagnostic p erformance of stereolithography vs workstation-based three-dimensional (3D) reformations in intra-articular calcaneal fractures. A total of 30 intra-articular calcaneal fractures were examined using standard ra diographs, coronal CT scans, and 2D and 3D reformations. The CT data w ere transferred to an outside institution, and stereolithograms were p roduced from photopolymer resin employing a laser beam system. 3D refo rmations and stereolithograms were analyzed in a blinded fashion by tw o staff radiologists. Receiver-operating-characteristic (ROC) curves w ere obtained for six clinically significant fracture components. Stand ard radiographs, coronal CT scans, and 2D reformations served as the s tandard of reference. The area under the ROC curves for 3D reformation s and stereolithograms were 1.0 and 0.98 for abnormal tuber angles, 0. 91 and 0.91 for anterior and middle talo-calcaneal joint involvement, 0.90 and 0.95 for involvement of the posterior talo-calcaneal joint, 0 .65 and 0.78 for the presence of a lateral bulge, 0.80 and 0.81 for th e involvement of the calcaneocuboidal joint, and 0.62 and 0.67 for the presence of a ''tongue-type'' fracture. No statistically significant difference was demonstrated for the two methods (Wilcoxon signed-rank test,p = 0.138). Based on our results stereolithograms did not prove t o be statistically superior to workstation-based 3D reformations. Ster eolithograms may still be useful for teaching purposes and for surgica l planning at a thinking-efficacy level.