[Navigated percutaneous placement of iliosacral screws using intra-operative three-dimensional imaging]

To investigate the effect of a new technique of navigated percutaneous placement of iliosacral screws using intra-operative three-dimensional (3D) imaging.

Sixteen patients with hip fracture were placed in supine position. After the reference marker was fixed on the iliac crest, a 3-D C-arm navigation system was used intra-operatively to obtain 3D images that were transferred to the navigation system by an automatic. Registration process to calculate the length of screw and direction to insert it. A navigated pointer defined the entry point, while navigated percutaneous drilling was done accordingly with a navigated drill bit in combination with a navigated drill sleeve under permanent dynamic control on the navigation screen without further intra-operative fluoroscopic imaging. A control intra-operative 3D scan was used to observe the position of the screws, while for didactic reasons another postoperative CT scan was done.

Twenty screws were successfully inserted into the first sacral vertebral bodies of the 16 patients. No additional intra-operative and postoperative complications occurred. The average operation time was 80 minutes and the average intra-operative radiation time was 1.13 minutes. Four patients underwent bilateral iliosacral fixation with longer operation time (152 minutes) and radiation time (1.56 minutes). The post-operative 3D scanning showed good results. No screws penetrated into the sacral canal or foramen. The reduction of fracture or dislocation and the position of iliosacral screws were all judged satisfactory.

Compared with the conventional fluoroscopy method, navigated percutaneous placement of iliosacral screws under intra-operative 3D imaging reduces the radiation time and improves the accuracy. It is feasible and useful though there are some disadvantages such as the inferior image quality compared to CT scan, prolonged operation time and higher overall cost.