[Variability of the screw position after 3D-navigated sacroiliac screw fixation. Influence of the surgeon's experience with the navigation technique].

BACKGROUND: The precision of sacroiliac screw placement can be improved with the use of navigation techniques. The purpose of this study was to evaluate the accuracy of 3D-navigated sacroiliac screw positioning in relation to the surgeon's experience with the navigation technique.

PATIENTS AND METHODS: A consecutive series of 3D-navigated sacroiliac screw placements were prospectively evaluated between December 2005 and February 2008. Postoperatively the precision of screw placement was analyzed in relation to the surgeon's navigation experience with a CT-scan using the criteria of Smith.

RESULTS: A total of 37 screws were implanted by 7 surgeons in 33 patients. In the group of surgeons with less experience in navigation techniques two cases of malpositioning led to revision of the screws. No screws which were implanted or assisted by surgeons experienced in navigation needed to be revised. There was no significant difference in the malposition rate.

CONCLUSION: In the clinical setup a malpositioning of sacroiliac screws is possible even with the use of 3D navigation. One reason may be a low level of navigation experience of the surgeon in combination with low experience in the conventional technique. Therefore even in navigation-based placement of sacroiliac screws the malpositioning rate is dependent on the surgeon's experience with the navigation technique. The correct placement of the screws should be controlled intraoperatively using the 3D image intensifier.