ABSTRACT
The placement of pedicle screws in spinal fixation still implicates a high complication risk and the success depends strongly upon the skills and experience of the surgeon. In order to enhance the precision and the safety of pedicle screw insertion, a mechanical drill guide is proposed to indicate the direction of the optimal path for the insertion of the screw. The aim of the project is to develop a patient dependent template that exactly fits some selected areas on the posterior part of a spinal segment incorporating drill holes indicating the correct position and orientation for the pedicle screws. The template can only be placed on the posterior part of one particular vertebra in one unique way. Using CT-images of the patient’s spine, pre-operative planning software enables the surgeon to determine the optimal position and orientation of the pedicle screw relative to the vertebrae. A CAD/CAM program uses the morphologic information of the vertebrae and the 3D information of the planned drill paths to design the template. The template is produced by stereolithography as rapid prototyping technique. The use of a Zeneca experimental resin which is sterilizable and USP Class VI guarantees evaluation during clinical trials. Four concepts of parametrized models have been completed based on CT-images of a patient’s L3-L5 segment and currently being evaluated.
