| 1 BackgroundAccording to home and abroad literature, we know that the anatomy of the thoracolumbar spine, especially that of vessels and nerves was done by scholars little even though no relevant reports. For the limitation or shortcoming of the traditional treatment, a number of technologies emerged, surgical approaches and new ideas began to appear, and were used in clinical, such as interbody fusion from the side, which requires us to study specially the basic anatomy of this area in order to meet clinical.The T11-L2 segments, due to small joints have not been fully from the frontal plane into the sagittal plane, are more vulnerable to be violence damaged by rotation and shear injury. Approximately 60% of thoracolumbar injuries occurred in this particular anatomical area. Therefore, the segment's diseases and surgery are a greater proportion. At present, the video-assisted thoracoscopic surgical(VATS) treatment of thoracolumbar fractures has been gradually spread at home and abroad, mainly used in the front exposure. The study of thoracoscopy-assisted retroperitoneal approach has been carried out at home and abroad, expected to be applied lateral fusion, anterior decompression. Some peritoneal approach damage easily the front blood vessels. The retroperitoneal approach due to the traditional posterior fusion led to complications such as postoperative pain, it is suggested by scholars that retroperitoneal approach for interbody fusion from the side.However, the special study about the side's neurovascular of the thoracolumbar spine at home and abroad was very few. In peritoneum approach some great blood vessels are likely to injury, while the retroperitoneal approach because the traditional posterior fusion led to complications such as postoperative pain, is suggested by scholars for interbody fusion from the side. However, we know from existed reports, the relevant segmental vascular injury is one of its major complications, therefore, to do a good job with video-assisted thoracoscopic thoracolumbar spine surgery must be familiar with the anatomical features of segmental vessels.However, the the relevant basic anatomy lags far behind, in order to adapt to the development of endoscopic surgery, the research of vessels and nerves is absolutely necessary. The way is to sum up past experiences and avoid a single mean of study, and using a variety of effective means to conduct a study could be more comprehensive and objective approach to acquire the relevant characteristics. At the same time, combined with previous studies deficiencies of this topic (preliminary studies only studied specimens, their research mean is not enough rich and conclusions should be further elaborated) to do something to add and modify. In view of this, to meet the clinical,this study was specifically done.2 Objectives2.1 To provide an anatomical shape base about the variation,the adjacent relationship and the course of the thoracolumbar spinal side segmental vessels and nerves. To identify the anatomical landmark and measure the distance between two adjacent segmental arteries as the largest safe zone of a surgical operation for video-assisted thoracoscopic thoracolumbar surgery.2.2 To provide the anatomic basis of imaging for the segmental vessels of the thoracolumbar spine side and measure the distance between two adjacent segmental arteries in the three-dimensional images.2.3 To provide the theoretical basis for preoperative using the imaging to develop individualized program. 2.4 To provide the outer anatomic basis of thoracolumbar spine for the video-assisted thoracoscopic surgical approach.2.5 To provide surgical approach and anatomy basis for video-assisted thoracoscopic thoracolumbar surgery.2.6 To provide an anatomical basis and related marks for the video-assisted thoracoscopic thoracolumbar spine surgery through the diaphragm.3 Methods3.128 anticorrosion fixed adult corpse specimens (56 sides,male 14, female 14, height 156-177cm) were chosen for this study. All specimens, provided by the Southern Medical University, Human Anatomy Department, had no local vascular disease, or other pathological changes. Removing the internal organs of thoracic and abdominal cavity of each specimen, then the parietal pleura and parietal peritoneum in the thoracolumbar spine segment; separating and removing diaphragm, psoas major muscle; fully displaying structures such as lateral blood vessels and nerves.Observing the course and the adjacent relationship of segment blood vessels, sympathetic trunk, great splanchnic nerve, aorta, azygos vein, hemiazygos vein.Measuring the distance between the upper and lower segment arteries in the mean line of the lateral thoracolumbar spine.3.2 After conducting angiography for 26(52 sides,13 males and 13 females) cases of normal adults through the ulnar vein, carring out thoracolumbar CT scanning. Before the scanning, inquiring the participant the medical record to exclude the thoracolumbar vertebra and the other related adjacent organization's illness, ensuring that volunteers in vivo without the metal implants, removing the body surface clothing's metal decorations, then let the volunteers rest 10 minutes in the peaceful hut to cause their mood to be affable, the breath steady. when scanning the body, keeping static as far as possible. Scanning range:The upper edge including the T3 vertebra upper edge, the lower edge surpassing the L5 vertebra lower edge. The participant taking the supine location.Image post-processing:All volunteers' primitive image had been inducted the CT image workstation by the BMP form, completed the maximum density projection (MIP), multiplane volume reconstructions (MPVR), volune rendering (VR),image reconstruction, MIP/MPVR/VR the image reconstruction level thick 0.1mm, MPVR/VR reconstruction image using the threshold value colored technology demonstration. In the image observation:The course and adjacent relationship of the segmental vessels, sympathetic trunk, splanchnic nerve, thoracic duct, azygos vein, half-azygos vein and the vertebral body. Measuring range(measurement processing using photoshop software):the distance between the the upper and lower segmental arteries of the middle line of spine side (if absence of segmental vessels, then measuring the distance between the mid-point of the level of vertebral body and another vessel).3.3 Comparing the observeing and surveing results between the corpse specimen and the imaging.3.4 Using two example anticorrosion fixed corpse specimens (male 1, height 173cm, female 1, height 161cm) to conduct layer by layer anatomy in the thoracolumbar spinal and observing the anatomy structure.3.5 Using one case fresh male adult specimen to simulate by paragraph thoracoscopic thoracic surgery and observing the anatomy. Analoging video-assisted thoracoscopic surgical procedures:lateral position, fixing and raising the specimen waist for the convenient of intercostal space openning and the equipment.accessing. Taking the anterior axillary line and the post-axillary line as a symbol, in the post-axillary line of the 8th,9th intercostal space, inserting the camera lens (light source), in the anterior axillary line 7th,8th, 5th,6th,.3rd,4th intercostal space inserting retractors, the working channel and the flushing operation of equipment such as suction tube so that more fully observing the spine side by making adjustments according to needing. Inserting 30°angle camera lens to observe the situation of the chest cavity, and inserting other 2-3 pipelines under the surveillance. When the lung collapse, affecting the spine observed, with a pull-hook fend off the lung, and by adjusting the inclination of operating table to strengthen the thoracolumbar spine observation. 3.6 Dissecting 12 adult fixed anticorrosion spcimens(male 6, female 6, height 156-177cm). After removing each specimen thoracic organ and exposing the costophrenic recess, simulating video-assisted thoracoscopic thoracolumbar spine anterior approach through the diaphragm to operate. Separating diaphragm at 1-2cm line from spine. Separating retroperitoneal space, exposing the medial arcuate ligament diaphragm, psoas major muscle, then removing psoas major muscle, fully revealing the left side of the lumbar spine and the surrounding blood vessels, nerves and other structures. In left surface of the upper lumbar, observing the anatomy significance of the surgical approach in the pleura back polyline (pleura lower bound), retroperitoneal space, the medial arcuate ligament and the crura diaphragmatis.measuring range:①The distance between pleural arteries back broken line and L1, the highest point of the medial arcuate ligament, visceral nerve piercing points, respectively;②The distance between the highest point of the medial arcuate ligament and L1 artery, L2 artery, lumbar sympathetic trunk piercing point (if the absence of lumbar arteries, measuring the distance between the lumbar vein or vertebral body and the the mid-point), respectively.3.7 Statisticalmethods Comparisons of means were performed using paired sample t-tests fot two sides, and the independent sample T-test in terms of gender and between the specimen and image. Conducting the correlation analysis between age, height and the each indicator. Statistics were performed using the SPSS for Windows software package (version 13.0, SPSS Inc., Chicago,Ill.) and probabilities of two sided P less than 0.05 were regarded as statistical significance.4 Results4.1 We could observe the side of the thoracolumbar spine on the adult corpse specimens, segmental arteries and veins exist and run in the central supersulcus of the corresponding vertebral body's side. An segmental artery has two main branches. That between the upper and lower segmental vessels consists a relatively non-vascular nerve safe zone where the intervertebral disc locates. And we surveyed the related datas. The distance between adjacent segmental arteries in the T10/11,T11/12,T12/L1,L1/2,L2/3 is, male:(23.86±0.69) mm, (26.20±0.46) mm, (29.43±0.57)mm,(32.96±0.32)mm,(34.13±0.37)mm and female:(22.91±0.32) mm,(25.53±0.60)mm,(28.61±0.24)mm,(32.23±0.38)mm, (33.41±0.26)mm respectively.4.2 We could observe the course and the adjacent relationship of thoracolumbar spine lateral vascular. That between the upper and lower segmental vessels consists a relatively non-vascular nerve safe zone where the intervertebral space locates. And we surveyed the related datas. The distance between adjacent segmental arteries in the T10/11,T11/12,T12/L1,L1/2,L2/3 is,male:(23.67±0.28)mm, (26.07±0.21)mm,(29.55±0.32)mm,(32.71±0.74)mm,(34.19±0.16)mm and female: (23.01±0.18)mm,(25.28±0.28)mm,(28.49±0.33)mm,(32.17±0.14)mm,(33.49±0.2 5)mm respectively.4.3 By the comparison of the observation and measurement results between specimens and images we can see:the course and adjacent relationship of the thoracolumbar segmental vessels are consistent. There is a relatively non-vascular nerve safe zone between the upper and lower segmental vessels. The difference was not statistically significant (P>0.05)4.4 We observed the anatomical structure of the dorsal spine and the abdominal side and understood the spinal column area adjacent relationship. And measured the length of crura diaphragmatis be 12.30cm, width 1.45cm, thickness 1.02cm. Further defined thoracolumbar spine surrounded by the anterior longitudinal ligament, crura diaphragmatis, greater psoas muscle.4.5 We observed that the video-assisted thoracoscopic spinal thoracolumbar anatomy.4.6 L1 artery locates in the middle of L1 vertebral.Incision the wall pleura at the T12/L1 disc.,down to the middle of vertebral body separating (19.56±0.58) mm can expose L1 artery. The highest point of the left medial arcuate ligament locates in the lower edge of the L1 vertebral level, slightly higher than the right position, but lower than the level of L1 artery about (6.24±0.33) mm, the distance from L2 artery is approximately (23.35±0.24) mm. Greater splanchnic nerve in the anterior-lateral of Li from pleural back broken line about (26.70±0.31) mm piercing diaphragm.Lumbar sympathetic trunk travels at the deep surface of the crura diaphragmatis in the lumbar lateral, lateral abdominal aorta.5 conclusions5.1 Safe zone can provide sufficient space for anterior thoracoscopic surgery, and taking the disc as a reference mark can reduce the damage of blood vessels, besides blocking blood vessels as little as possible can ensure that the spinal cord segmental arterial blood supply and reduce complications.5.2 Three-dimensional reconstruction of CT images can effectively observe the course and adjacent relationship of the thoracolumbar spinal lateral segmental artery, and can accurately measure the safe zone.5.3 The segmental arteries results of the observation and measurement are consistent between specimens and CT three-dimensional images, so in the preoperative, CT three-dimensional image can be used as the plan for operation.5.4 Familiar with the general anatomy can avoid injuring related organizational structure.5.5 Familiar with the microscopic anatomy of thoracoscopic can avoid injuring related organizational structure.5.6 Pleural back broken line, medial arcuate ligament, visceral nerve piercing point can be marked as the surgery.The principal innovation of this study1. Through the study of the specimens in the thoracolumbar spine side, we found between the two adjacent segmental arteries form a relatively safe zone without vessels and nerves, intervertebral discs (gap) locate in the middle part of this safe zone. If carry out between the two vertebral segments or a single operation, we can operate in this safe zone without the ligation of segmental arteries. When multi-segmental anterior spinal surgery, we can also minimize the number of ligation of segmental arteries. Therefore, taking the disc (gap) as anatomical landmark can reduce the damage to the vessels and nerves and reduce complications.2. Using the imaging methods (imaging, three-dimensional reconstruction, etc.) to study the side segmental vessels of the thoracolumbar can show the anatomical features of segmental arteries and thus provides a segmental vascular anatomy base of imaging.3. Through a comparative study of the results of cadaver dissection and imaging anatomy, imaging results obtained in full compliance with the findings of specimens, and further imaging studies obtained segmental arteries display is accurate.We conclude that, preoperative the three-dimensional reconstruction of segmental arteries can be personalized for the surgical operation to develop the program.4. After relatively analysing of height,age and each item,we find that there is relative relationship between the height and each item,but there is no relative relationship between the age and each item.5. By providing the safe zone specific anatomic parameters of specimens and imaging, it provides the anatomical basis for the design and ideas of clinically relevant equipment.
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