Navigation of tumor and metastatic lesions in the thoracolumbar spine

Abstract

Since the description of transpedicle fixation of posterior spinal implants by Roy-Camille et al. [22], this procedure has gained general acceptance for rigid segmental fixation. Correct implantation of the screws without perforation of the pedicle is difficult and requires detailed anatomic knowledge and good surgical skills. The identification of the correct entry point for the pedicle screw and the angle of inclination in the sagittal and transverse planes are crucial. A standard technique for pedicle screw insertion is done with an image intensifier in the lateral and anteroposterior (AP) views. In osteolytic tumors identification of anatomical landmarks is difficult and intra-operative imaging can be impossible due to increased radio translucent vertebrae. Computed tomography (CT)-controlled studies have had significant rates of incorrect placement of lumbar transpedicle screws [6, 10, 29]; implant-related and neurologic complications have also been reported [7, 30]. The central implant placement in the thoracic pedicle is a more difficult procedure [32], and an increasing rate of misplacement can be expected in this region. Within the past years, computer-aided systems for CTbased freehand navigation have been introduced [19, 28]. With this technique, a pre-operative CT scan (CT dataset) is superimposed onto the intra-operative rigid body (the spinal vertebra). As long as the navigated vertebra is non-deformable, online visualization of the instruments within the preoperative data set is possible. In addition, it accurate visualization of the tumor can be obtained preoperatively using CT or magnetic resonance imaging (MRI) scans, which can provide safer surgery for the patient. The aim of this clinical feasibility study was to investigate the efficacy of a computer-aided visualization technique during neural decompression and transpedicle stabilization in patients who require tumor-related surgery of the spine. © 2007 Springer Medizin Verlag Heidelberg.