An international, multicenter, prospective, postmarketing clinical registry to record the accuracy of pedicle screw placement, using the O-arm Complete Multidimensional Surgical Imaging System with StealthStation Navigation. To evaluate the accuracy of pedicle screw placement in common neurosurgical practice and assess the patient's radiation exposure. Several imaging techniques have been used to increase accurate pedicle screw placement. The O-arm 3-dimensional (3D) imaging (Medtronic Navigation, Louisville, CO), an intraoperative computed tomographic (CT) scan, combined with an existing navigation system was reported to further increase accuracy of screw placement, especially because an intraoperative 3D scan provides information for screw adjustment before wound closure. Patients already planned for instrumented spinal surgery were operated while using the O-arm as imaging device and the StealthStation Navigation (Medtronic Navigation, Louisville, CO) as navigation tool. At the end of all pedicle screw insertions, the placement was classified according to a validated method. The accuracy of pedicle screw placement based on the intraoperative 3D scan and the surgeon's perception of correct screw placement were assessed as well as the radiation doses the patient received during the entire procedure. During a 16-month period, a total of 1922 screws in 353 patients were evaluated. In 97.5%, the screws were correctly placed. Only 2.5% of the screws were considered as misplaced, and 1.8% of the screws were revised during the same procedure. When the surgeon perceived the screws to be correctly placed, the CT scan verified his assessment in 98.5% of the cases. The mean radiation dose was comparable with half the dose of a 64 multislice CT scan. The use of the O-arm in combination with a navigation system increases the accuracy of pedicle screw placement. The accuracy of the surgeon's perception and the need to limit the radiation dose for the patient justify an additional CT scan only after careful assessment of the potential additional value.

Blocking angiogenesis is an attractive strategy to inhibit tumor growth, invasion, and metastasis. We describe here the structure and the biological action of a new cyclic peptide derived from vascular endothelial growth factor (VEGF). This 17-amino acid molecule designated cyclopeptidic vascular endothelial growth inhibitor (cyclo-VEGI, CBO-P11) encompasses residues 79-93 of VEGF which are involved in the interaction with VEGF receptor-2. In aqueous solution, cyclo-VEGI presents a propensity to adopt a helix conformation that was largely unexpected because only beta-sheet structures or random coil conformations have been observed for macrocyclic peptides. Cyclo-VEGI inhibits binding of iodinated VEGF165 to endothelial cells, endothelial cells proliferation, migration, and signaling induced by VEGF165. This peptide also exhibits anti-angiogenic activity in vivo on the differentiated chicken chorioallantoic membrane. Furthermore, cyclo-VEGI significantly blocks the growth of established intracranial glioma in nude and syngeneic mice and improves survival without side effects. Taken together, these results suggest that cyclo-VEGI is an attractive candidate for the development of novel angiogenesis inhibitor molecules useful for the treatment of cancer and other angiogenesis-related diseases.

A retrospective clinical and radiological study. To compare the safety and accuracy of pedicle screw insertion using two different computed tomography (CT) data set acquisitions (preoperative and intraoperative) for computer-guidance systems in a series of 100 consecutive patients. Misplacement and pedicle cortical violation occurs in over 20% of screw placements and can result in potential neurovascular complications. Many technological innovations have been described to help reduce this range of error, such as image-guided surgery using fluoroscopy or CT-based image guidance. However, these techniques are not without their drawbacks. The next technological evolution is the use of an intraoperative CT scan, which would allow us to solve some of the critical phases of spinal navigation, such as position-dependent changes, thus granting a higher accuracy of the navigation system. The authors have compared and discussed the results of a preoperative and intraoperative CT data set acquisition mode for spinal navigation. One hundred consecutive patients with a diagnosis of lumbar degenerative spondylolisthesis who underwent a surgical approach of lumbar pedicle screw fixation using a CT-based computer-guidance system were evaluated. The population was divided into two groups: in group I, a preoperative CT scan was used for the navigation system; whereas in group II, an intraoperative CT scan acquired during surgery was used. Epidemiological and surgical data of the patients in the two groups were then analyzed and compared. The Pearson χ2 test was used for comparisons between groups (significance level 0.05). The evaluation and classification of the screw positioning was performed on the basis of a control CT scan according to the classification proposed by Laine. Out of 504 screws, 471 were correctly inserted into the pedicles (93.5%): the accuracy of group I was of 91.8%, whereas in group II it was 95.2% (no statistical significance). The overall rate of perforation was 6.5% (33 screws): 21 in group I and 12 in group II. Twenty-eight screws had a perforation of the pedicle less than 2 mm (Grade I), three comprised from 2 to 4 (Grade II), and only two more than 4 mm and less than 6 mm (Grade III). Out of 33 misplaced screws only one was replaced (graded as III in group II). Surgical time was shorter for group II, with a statistically significant difference. This result is mainly because of the automatic recognition and merging of the intraoperative images with the surgical anatomy that avoided the phase of registration with a paired-point technique. The results of this study suggest that the CT-based computer-assisted surgical navigation systems are precise, granting an elevated accuracy in pedicle screw positioning.

The present study proposes a semi-automatic software approach to reconstruct 3D subject-specific musculoskeletal model of thoraco-lumbar spine from radiographic digitized images acquired with EOS system. The approach is applied to evaluate the intervertebral loads in 38 standing adolescents with mild idiopathic scoliosis. For each vertebra a set of landmarks was manually identified on radiographic images. Coordinates were processed calculating vertebral configuration in 3D space: i) location; ii) dimensions; iii) rotations. Spherical joints simulated discs, ligaments and facet joints. Body weight distribution, muscles forces and insertion points were placed according to physiologic-anatomical values. Inverse static analysis, calculating joints reactions in maintaining assigned spine configuration, was performed with AnyBody software. Reaction forces were computed to quantify intervertebral loads and correlation with the patient anatomical parameters was then checked. Preliminary validation was performed comparing the model outcomes with that obtained from other authors in previous modelling works and from in vivo measurements. The comparison with previous modelling works and in vivo studies partially fulfilled the preliminary validation purpose. However, minor incongruities were pointed out that need further investigations. The subjects intervertebral loads were found significantly correlated with the anatomical parameters in the sagittal and axial planes. Despite preliminary encouraging results that support model suitability, future investigations to consolidate the proposed approach are necessary. Nonetheless, the present method appears to be a promising tool that once fully validated could allow the subject-specific non-invasive evaluation of a deformed spine, providing supplementary information to the routine clinical examination and surgical intervention planning.