Intraoperative Position Determination of Bone Cement Trocars by 3-dimensional Imaging in Patients With Osteoporotic Vertebral Fractures

Study Design: A prospective diagnostic study to evaluate the use of intraoperative 3-dimensional (3D) imaging. Objective: To evaluate the accuracy of an intraoperative 3D imaging predicting trocar positions in osteoporotic fractured vertebral bodies before cement injection. Summary of Background Data: Malpositioned needles in vertebroplasty and kyphoplasty increase the risk of extravertebral cement leakage and the associated complications. This study was intended to clarify whether the position of trocars can adequately be determined before the cement application by an intraoperative 3D imaging. Methods: Between August 2006 and July 2008 the positions of 84 trocars in 42 fractured vertebrae between T11 and L5 were measured by intraoperative 3D imaging before injection of the cement. The external diameter of the needles was 9 to 10G. The positions of the trocars were classified in the axial plane by a new classification system. Results: Forty 3D scans covered 84 injection cannulae in 42 fractured vertebral bodies. The average duration of the entire scanning procedure was 7.1 minutes. All 3D scans could be evaluated with adequate degree of certainty. Intraoperative evaluation of the 3D scans showed 78 correct needle positions. Two trocars were in an acceptable lateral malposition. There were 4 medial malpositions that required revision. In total, 4.8% of the trocars were positioned not acceptably. Postoperative computed tomography was performed in 17 patients. The positions of 34 needles determined by computed tomography conformed 100% to the results of the 3D scans. Conclusions: It is possible to reliably determine the position of trocars in vertebral bodies with the aid of an intraoperative 3D scan. This can lead to a reduction in the morbidity rates associated with puncture errors in kyphoplasty and vertebroplasty. The amount of time required is small. The increased radiation exposure is acceptable.