Background: Through the comparison of three-dimensional CT reconstruction between the supine position and the prone position, the relative position of thoracolumbar great vessels and vertebral body was studied, and the shortest safe distance between them was measured to improve the safety of bicortical pedicle screw insertion and reduce the risk of vascular injury. Methods: Forty adults were selected to participate the research. Three-dimensional reconstruction of thoracolumbar (T9-L3) CT was performed in the prone position and the supine position. The relative distance between the Aorta/Inferior Vena Cava (IVC) and vertebral body was obtained as AVD/VVD respectively. The relative angle of the Aorta/ IVC and the vertebral body was calculated as ∠AOY/∠VOY. Self-controlled experiments were carried out in the prone and the supine positions, and the data obtained were analyzed using SPSS 22.0 statistical software. Results: The AVD of the prone position and the supine position was the shortest at T12 (3.18 ± 0.68 mm), but the difference was not statistically significant. The aorta of the T9-L3 segment was shifted from the anterolateral to the anteromedial. The ∠AOY of the other groups differed significantly between the prone and supine positions in all vertebrae except T12 and L1 (P < 0.05), and the aorta in the prone position was more anteromedial than that of supine position. With regard to VVD/∠VOY, there was no significant difference between the prone and supine positions (P ≥ 0.05), and the minimum VVD of L3 segment is greater than 5.4 mm. The IVC has no obvious mobility and is fixed in the range of 20°~30°near the midline.

Background: Through the comparison of three-dimensional CT reconstruction between the supine position and the prone position, the relative position of thoracolumbar great vessels and vertebral body was studied, and the shortest safe distance between them was measured to improve the safety of bicortical pedicle screw insertion and reduce the risk of vascular injury. Methods: Forty adults were selected to participate the research. Three-dimensional reconstruction of thoracolumbar (T9-L3) CT was performed in the prone position and the supine position. The relative distance between the Aorta/Inferior Vena Cava (IVC) and vertebral body was obtained as AVD/VVD respectively. The relative angle of the Aorta/ IVC and the vertebral body was calculated as ∠AOY/∠VOY. Self-controlled experiments were carried out in the prone and the supine positions, and the data obtained were analyzed using SPSS 22.0 statistical software. Results: The AVD of the prone position and the supine position was the shortest at T12 (3.18 ±0.68mm), but the difference was not statistically significant. The aorta of the T9-L3 segment was shifted from the anterolateral to the anteromedial. The ∠AOY of the other groups differed significantly between the prone and supine positions in all vertebrae except L1 (P < 0.05), and the aorta in the prone position was more anteromedial than that of supine position. With regard to VVD/∠VOY, there was no significant difference between the prone and supine positions (P≥0.05), and the minimum VVD of L3 segment is greater than 5.4mm. The IVC has no obvious mobility and is fixed in the range of 20 °~ 30 ° near the midline. Conclusion: When using bicortical anchoring of pedicle screws, it is safe to ensure that the protruding tips of the screw is less than 3mm. Due to the mobility of the aorta in different postures and individual differences in anatomy, the prone position CT can help doctors to make better preoperative plans and decisions.

No abstract

Background: Three-dimensional CT reconstruction of prone position could measure the relative position between the Great vessels and the thoracolumbar vertebrae. The Great vessels positions of the thoracic and lumbar segments were studied to improve the accuracy of pedicle screw insertion, reduce the risk of vascular injury. Methods: Twenty-four adults participated in the present study. Three-dimensional reconstruction of thoracolumbar (T9–L3) CT was performed in the prone and supine positions. The relative distance between the arteriovenous vessels and vertebrae distance (AVD/VVD) was obtained, respectively. The relative position angle of the arteriovenous vessel and the vertebral body was calculated as ∠AOY/∠VOY. Self-controlled experiments were carried out in the prone and supine positions. The data obtained were analyzed using SPSS 22.0 statistical software. Results: With regard to AVD, The AVD of the T12 was the smallest,> 3.2 mm. The difference among the T9, T10, L2 level was statistically significant (P < 0.05). And AVD was greater in the prone position than in the supine position; while the value of ∠AOY is the descending from T9-L3 gradually, there were statistically significant differences in ∠AOY between T9-T12, L2 and L3 in prone and supine position (P < 0.05). The aorta in the prone position was closer to the midline than that of the supine position, varying from 0°to 30°near the Y axis. With regard to VVD, there was no significant difference in contrast between the prone and supine positions (P≥0.05), and the VVD was the smallest in the L3 level> 5.4 mm. Conclusion: The pre-vertebral position of the aorta may change from T9 to L3 due to changes in body position. When the T9-L3 thoracolumbar spine disease was treated with pedicle screw double cortical fixation, the screw was safe and reliable within a range of≤ 3 mm when broken the pre-cortex .The three-dimensional reconstruction of prone position CT could be used to more accurately assess the relative position of the vertebral body and the blood vessel.