Fluoroscopy-based multiplanar image guidance for insertion of sacroiliac screws

A prospective controlled experimental study was done to assess the value of fluoroscopy-based, computer-assisted orthopaedic surgery for the insertion of sacroiliac screws and to compare this new technology with the conventional technique, using image intensification. In a simulated surgical setup, 140 cannulated screws were placed into the S1 and S2 vertebral bodies of 35 pelvic models. The screws were inserted under fluoroscopy-based image guidance or with the conventional technique. Different drills were tested with both techniques, including a 2.8-mm guide wire and a 5-mm solid drill. The 2.8-mm guide wire proved inaccurate with the computer-assisted image guidance system because of guide wire flexibility. Using the more rigid 5-mm drill, the results of computer-assisted image guidance were comparable with the image intensifier technique. The radiation exposure during screw insertion was reduced considerably when using the image guidance system. System-specific requirements warranted adjustment of surgical technique and instruments. The major advantages of this new technology are immediate intraoperative image acquisition and provision of surgical guidance in as much as four planes simultaneously. The results of this experimental study are encouraging and have led to initiation of a clinical trial.