GUIDING TEMPLATES FOR PEDICLE SCREWS INSERTION: A PRELIMINARY STUDY

Abstract

Fixation of pedicle screws necessitates high surgical skill and a great deal of experience in order to avoid injuries to nerves and vessels. In this study, we develop a computer-aided procedure to produce personalized drill guides that are designed to enhance the safety of pedicle screw insertion in the spinal region. Based on a patient's computed tomography (CT) data, it is possible to design personalized drill guides in a self-developed computer-aided design environment. These guides are designed to fit on the surface of vertebrae in a unique position in order to indicate both the preplanned drill path and the drilling length into the pedicle. A rapid prototyping device is used as a three-dimensional printer to produce the shape of reference areas on bone surfaces. Postoperative CT scans are obtained, and the accuracy of the pedicle screws is measured. By using customized templates in a case study, the guiding templates are shown to be highly accurate and to provide great assistance for planning and executing surgeries. The accuracy of screw placement is confirmed with postoperative CT scanning. The average angle of the drilling paths between planning and postsurgery is approximately 1.05°. The average deviation of entry points of drilling paths between planning and postsurgery is approximately 2.99 mm. The performance proves a high degree of accuracy in comparison with conventional techniques achieved through fluoroscopy. However, a significant number of clinical cases is needed to validate the feasibility of this method. The device is proven to be reliable and compatible; in the future, surgeons can use the guiding templates to complete more complicated cases such as those involving idiopathic scoliosis and cervical complications.