Clinical application of computer-assisted navigational template for femoral corrective osteotomy in developmental dysplasia of the hip

Abstract

Objective To develop and validate a novel method of femoral corrective osteotomy by reverse engineering and rapid prototyping and explore its clinical application. Methods Between July 2011 and April 2012, computed tomography(CT) scans were performed for 11 cases of developmental dysplasia of the hip(DDH). The imaging data were transferred into the Mimics software. After reconstruction, a three-dimensional femoral model was established, saved in .stl format and imported into Imageware 12.0 software for determining the three-dimensional plane of reference. The optimal Kirschner wire channel for derotational femoral shortening osteotomy was extracted according to the principle of reverse engineering. The template was designed according to anatomic features of femoral surface and optimal osteotomy channel. Template was overlapped with navigational template manufactured by rapid prototyping. The template was placed distally on external femur. And the location for Kirschner wire insertion was defined by navigation template. The accuracy of screw placement was confirmed by postoperative radiology and CT scan. Results The digital navigational template had been established and used in all 11 cases. During a follow-up period of 12-18 months, there was no onset of such major osteotomy-related complications as redislocation or avascular necrosis. All actual femoral anteversion angles corresponded almost exactly to the planned corrective ones. Conclusions A novel method of derotational femoral shortening osteotomy has been developed with reverse engineering and rapid prototyping. And navigational template has a high accuracy and holds great prospects. It provides a new method of managing DDH in children. Key words: Hip dysplasia; Osteotomy; Surgery, computer-assisted