Clinical application of computer-assisted navigational template in Hangman fracture surgery

Abstract

Objective To provide accurate location for pedicle fixation with the help of computerassisted navigational template in hangman fracture surgery. Methods CT scanning of patients with Hangman fracture was performed, and three dimensional (3D) model of Hangman fracture was constructed by using software MIMICS 10.01. The 3D model was then exported in STL format, and opened in a workstation running software UG imageware12.0. The optimal pedicle channel was located according to reverse engineering. A virtual navigational template was established according to the laminar anatomic trait. The physical vertebrae and navigational template were manufactured by using rapid prototyping. The navigational template was sterilized and used to assist the placement of Hangman fracture pedicle screw. The C3 navigational template was made with the same method. The placement of the screws was confirmed by postoperative X-ray and CT scanning. Results Four patients were involved in the study, of whom two patients received C2 and C3 fusion and the other two patients received C2 pedicle fixation. A total of eight C2 pedicle screws and four C3 pedicle screws were inserted. The navigational template was found to be highly fit with the lamina of vertebra. No nerve or blood vessel complication was observed during and after operation. Conclusions The navigational template designed according to reverse engineering and made by rapid prototyping can facilitate cervical pedicle location and make posterior operation for Hangman fractures safer. Key words: Spinal fractures; Axis; Surgery; computer-assisted; Hangman fractures