Application of three-dimensional printed navigation template in proximal femoral varus rotation and shortening osteotomy for elder children with developmental dysplasia of the hip

Abstract

Objective To use reverse engineering (RE) and rapid prototyping (RP) technology for designing a new navigation template and explore its feasibility in proximal femoral varus rotation and shortening osteotomy for elder children with developmental dysplasia of the hip (DDH). Methods Between June 2014 and December 2014, computed tomography (CT) scans were performed for 6 cases of DDH. Mimics & Geomagic Design Direct software was used for designing a navigation template for including all operative parameters and steps for proximal femoral varus rotation and shortening osteotomy. Template generated by fused deposition molding (FDM) of RP technology was placed distally on proximal femur. After placing Kirschner wire, bone was cut along the navigation template. And Kirschner wire was utilized as a lever for insertion into screw hole of plate after template removal. And cortical screw was placed for completing operation. Results Intraoperative operation was consistent with preoperative measurements and simulation operation. The average operative duration was 18(14-21) min. Six patients (6 hips) were followed postoperatively for 12-18 months. According to the McKay criteria, the outcomes were excellent (n=4, 66.7%), good (n=1, 16.7%) and fair (n=1, 16.7%) with a fineness ratio of 83.3%. And based upon the Severin radiographic criteria, the outcomes were excellent (n=5, 83.3%) and good (n=1, 16.7%) with a fineness ratio of 100%. There was no onset of such major osteotomy-related complications as redislocation or avascular necrosis. Conclusions During proximal femoral Varus rotation and shortening osteotomy for elder DDH children, this novel navigation template may improve operative precision, simplify operative procedures and ensure efficacies. Key words: Developmental dysplasia of the hip; Osteotomy; Three dimensional printing