PubMed · 4839679
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
K S Ternovoĭ, G I Lyuzov. 1974. [Compression-distraction reduction apparatus].. https://pubmed.ncbi.nlm.nih.gov/4839679/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Currently there are few data available regarding the application and efficacy of computer-assisted procedures in the sacral spine. In order to optimize and standardize this procedure, a controlled experimental investigation has been performed. The aim of the study is to systematically assess the efficacy of a novel three-dimensional image intensifier used for navigated transiliac screw insertion into the first sacral vertebra. Screws were inserted iliosacrally into the first sacral vertebra of preserved human cadaver specimens. The instrument navigated procedure was performed with the "Siremobil Iso-C(3D) " (Siemens Medical Solutions) and the "Navigation System" by Stryker. The accuracy and quality of the imaging procedure as well as the fluoroscopic exposure times were measured. These results were compared to three control groups (CT-based navigation, C-arm navigation, and fluoroscopic guidance). In each group a total amount of 20 screws was implanted. Screw position was postoperatively assessed by Iso-C(3D) or CT-scan. The navigated procedure using the Iso-C(3D) provided good feasibility characteristics without requiring a specific matching process. It revealed the shortest procedure time of all navigated procedures and significantly decreased fluoroscopic time compared to C-arm navigation and fluoroscopic guidance. Furthermore, Iso-C(3D) navigation showed no screw malposition and was in this regard superior to C-arm navigated and fluoroscopic guided procedures. The quality of imaging was sufficient for accurate placement, but did not share the high-resolution level of CT-based navigation. These findings indicate that application of the Iso-C(3D) for navigated transiliac screw insertion into S1 can be recommended as a feasible and safe technique, enabling the surgeon to reduce procedure and fluoroscopic time. Further progress in improving the quality of the Iso-C(3D) image should be attempted.
STUDY DESIGN: A cadaveric study comparing image guidance technology to fluoroscopic guidance as a means of pedicle screw placement in the thoracic spine, using a unique starting point for screw placement. OBJECTIVE: To assess accuracy of thoracic pedicle screw placement using image guidance versus fluoroscopic guidance for screw insertion. SUMMARY OF BACKGROUND DATA: While use of pedicle screws in the thoracic spine has been increasing, its adoption has been slower than for the lumbar spine, reflecting concern regarding possible vascular or spinal cord injury due to screw malplacement. Given these risks, efforts to improve the accuracy of thoracic pedicle screw placement remain appropriate. Stereotactic guidance has been applied in other aspects of spinal surgery to improve the accuracy of instrumentation placement. METHODS: Pedicle screws were placed in the thoracic spines of eight cadavers, using either a stereotactic guidance or a manual, fluoroscopically guided technique. A slightly more superior and lateral starting point from prior descriptions was used. Each cadaver was instrumented with pedicle screws in the upper thoracic (T1-T2), middle thoracic (T4-T7), and lower thoracic (T9-T10) regions. In the upper and middle thoracic regions, screws with a 4.0-mm shank diameter were used while in the lower thoracic region a shank diameter of 4.5 mm was used. Postinstrumentation CT scans, followed by anatomic dissections, were used to evaluate screw exit rates and orientation relative to the pedicle axis. Exit rates for the two techniques and the effect of vertebral level on exit rate were compared using a chi analysis. The effect of pedicle diameter was tested using a Pearson correlation coefficient. RESULTS: No significant differences in the overall exit rates or orientation were found between the two techniques. There were significant differences in exit rates between the middle (47%), compared with the upper (9%) and lower (16%) thoracic regions, respectively (P < 0.001). A significant correlation between pedicle diameter and exit rate was also found (P < 0.0001). CONCLUSION: Our study showed no significant differences in the overall exit rates between the two techniques. Image guidance may increase confidence of surgeons with limited experience in thoracic pedicle screw placement. Successful placement of screws within the pedicle varies with the anatomic diameter of the pedicle itself. Concerns regarding accuracy of screw placement should be greatest in the middle thoracic vertebrae (T4-T7), where pedicle diameters are smallest and proximity of the great vessels is nearest.
Today, posterior stabilization of the cervical spine is most frequently performed by lateral mass screws or spinous process wiring. These techniques do not always provide sufficient stability, and anterior fusion procedures are added secondarily. Recently, transpedicular screw fixation of the cervical spine has been introduced to provide a one-stage stable posterior fixation. The aim of the present prospective study is to examine if cervical pedicle screw fixation can be done by low risk and to identify potential risk factors associated with this technique. All patients stabilized by cervical transpedicular screw fixation between 1999 and 2002 were included. Cervical disorders included multisegmental degenerative instability with cervical myelopathy in 16 patients, segmental instability caused by rheumatoid arthritis in three, trauma in five and instability caused by infection in two patients. In most cases additional decompression of the spinal cord and bone graft placement were performed. Pre-operative and post-operative CT-scans (2-mm cuts) and plain X-rays served to determine changes in alignment and the position of the screws. Clinical outcome was assessed in all cases. Ninety-four cervical pedicle screws were implanted in 26 patients, most frequently at the C3 (26 screws) and C4 levels (19 screws). Radiologically 66 screws (70%) were placed correctly (maximal breach 1 mm) whereas 20 screws (21%) were misplaced with reduction of mechanical strength, slight narrowing of the vertebral artery canal (<25%) or the lateral recess without compression of neural structures. However, these misplacements were asymptomatic in all cases. Another eight screws (9%) had a critical breach. Four of them showed a narrowing of the vertebral artery canal of more then 25%, in all cases without vascular problems. Three screws passed through the intervertebral foramen, causing temporary paresis in one case and a new sensory loss in another. In the latter patient revision surgery was performed. The screw was loosened and had to be corrected. The only statistically significant risk factor was the level of surgery: all critical breaches were seen from C3 to C5. Percutaneous application of the screws reduced the risk for misplacement, although this finding was not statistically significant. There was also a remarkable learning curve. Instrumentation with cervical transpedicular screws results in very stable fixation. However, with the use of new techniques like percutaneous screw application or computerized image guidance there remains a risk for damaging nerve roots or the vertebral artery. This technique should be reserved for highly selected patients with clear indications and to highly experienced spine surgeons.