PERCUTANEOUS ILIOSACRAL SCREW PLACEMENT USING IMAGE-GUIDED TECHNIQUES

A computer assisted technique of iliosacral screw placement that is ap plicable to unstable pelvic ring fractures is proposed, The goals are to operate noninvasively with a percutaneous procedure to decrease the complications of surgical exposure and to provide greater accuracy in locating the dose neurovascular structures. Preoperative computed tom ographic images of the pelvis are provided and a computed tomography t hree-dimensional model is built. In this model, the optimal trajectori es for the drilling are planned. An ultrasound based registration is p erformed intraoperatively, This registration is the most original part of this work. After performing the passive drilling guidance step, th e surgeon places the screws. The accuracy of the ultrasound based regi stration is checked by comparison with a standard surface based regist ration at the end of the test experiment. Each screw position is verif ied by a computed tomographic examination. Four human anatomic specime n pelves were tested with three screw insertions for each pelvis (12 s crews). All of the screws were considered to be placed correctly. The method is safe and encourages the start of clinical application.