Image-based planning and validation of C1-C2 transarticular screw fixation using personalized drill guides

Abstract

Posterior transarticular spine fusion is a surgical procedure used to stabilize the cervical bodies C1 and C2. Currently, spine screws are used most frequently, according to the procedure of Magerl. As the anatomy is rather complex and the view is limited, this procedure has a high risk factor. Thus we present and validate a planning system for cervical screw insertion based on preoperative CT imaging. It allows a neurosurgeon to interactively determine the desired position of the cervical screws, based on appropriate and in real-time calculated reslices through the preoperative CT data. Guided by this information, a personalized mechanical drill guide is produced. The system is validated by five cadaver experiments. Based on the preoperative planning, screws are inserted through the drill guide. A semi-automatic technique is used to extract the screw locations from the postoperative images. The deviations of the axes of the planned and the inserted screws are determined in this way. We have observed that the drill guides are not yet stable enough to cope with the drilling forces that they are subjected to. As a result, they tend to displace. However, most of the inserted screws were judged to be adequately placed. No vascular compromise nor invasion of the spinal canal was observed.