Burst fractures and dislocations of two adjacent segments of the thoracolumbar vertebrae are often caused by great violence, with complex injury mechanisms, and most of them are unstable fractures with spinal cord injury, so they require early surgical treatment. Because of the different mechanisms of injury with a single thoracolumbar vertebral fracture, the use of simple internal fixation with pedicle screws across the upper and lower normal vertebral bodies of the injured vertebrae often leads to failure of internal fixation surgery, and the extension of the fixed segments can provide sufficient spinal stability, but at the expense of a number of normal spinal motility units, so this type of fracture is more tricky to treat in the clinical setting. 1, the clinical characteristics of adjacent two-segment thoracolumbar fractures adjacent two-segment thoracolumbar fractures are less common than single thoracolumbar spine fractures, mostly caused by greater violence, complex mechanism of injury, and more combined injuries, with a single fracture with different clinical characteristics: (1) Calneff et al. put forward the theory of multiple spinal fractures of the primary and secondary injuries: violence directly caused by the first fracture for the primary fracture, the violence caused by the conduction of adjacent or intermediate fractures for the secondary fracture. The first fracture directly caused by violence is the primary fracture, and the adjacent or intermediate fracture caused by conduction of violence is the secondary fracture. Usually the primary fracture is more severe and the secondary fracture is less severe. The thoracolumbar segment of the spine is the “inflection point” of spinal biomechanics, where violence generates shear forces in different directions, so it often becomes the primary fracture site of the spine and the key point of injury in fall from height injuries. Among the 34 patients in this group, T11-L2 fractures accounted for 27 cases (79%), and there were 19 cases (56%) of fall from height injuries, which is in line with the literature reports.2) Some of the A1 types of secondary injuries to the vertebral body are easy to miss on X-ray, and need to be diagnosed by CT or MRI. With the deepening of the understanding of multisegmental spinal fractures and the popularization of clinical CT and MRI, the rate of missed diagnosis is getting lower and lower.3) Injury-causing violence is large, and the probability of combining with other organ injuries increases. 2, the choice of surgical and non-surgical treatment options for spinal fractures of two adjacent segments Thoracolumbar burst fracture makes the vertebral body serious bone damage, and the purpose of the surgery is to relieve the compression of the spinal canal, correct spinal deformity, restore the height of the vertebral body and stabilize the spine. The commonly used posterior pedicle screw internal fixation is considered to be the gold standard for the treatment of this type of fracture because of its simplicity and minimal damage. Currently, there is still some debate about the treatment of thoracolumbar fractures of two adjacent segments, but most scholars believe that the indications for surgery for multisegmental spinal fractures should be relaxed compared with those for single-segment spinal fractures, and that surgical treatments are more effective than non-surgical treatments in cases of unstable spinal fractures or those with spinal cord neurological function impairment. Because the adjacent two consecutive segments of thoracolumbar fractures are multiplanar fractures, stress dispersion, and loss of spinal stability, although the anterior surgery can directly remove the fragmented bone that compresses the spinal cord, it is more difficult to carry out effective internal fixation, and the surgical trauma is large, with much blood loss. The technique of posterior pedicle screw internal fixation is associated with simple anatomy, less trauma, and simple operation, and is especially suitable for patients with multiple injuries. However, posterior pedicle internal fixation is inconclusive in the selection of fixation and fusion segments. Previous long-segment posterior endoprosthetic fixation across the injured vertebrae can strongly stabilize the spine in the treatment of consecutive two-segment thoracolumbar fractures, but at the expense of the spinal motion segments, resulting in postoperative spinal stiffness, pain, and severe degeneration of the adjacent segments and many other complications. 3, the biomechanical characteristics of posterior 4 vertebrae 4 nails, 4 vertebrae 6 nails and 4 vertebrae 8 nails internal fixation Posterior 3 vertebrae 4 nails short segment pedicle screw reset internal fixation of single vertebrae fracture of thoracolumbar vertebrae is the gold standard for the treatment of thoracolumbar vertebrae fracture, however, with the increase in the number of clinical applications, there are more failures of internal fixation and the loss of deformity correction. Analysis of biomechanical studies has shown that after internal fixation of pedicle screws, the main force acting on the screws is the cantilever curvature force (suspension effect), and in the case of vertebral burst fracture resulting in failure to reconstruct the anterior mid-column injury, this cantilever curvature force is loaded more heavily, and thus easily leads to broken nails and broken rods. This, coupled with the parallelogram effect of the 3-vertebral 4-nail, further promotes failure of internal fixation. Some scholars have proposed the application of 3-vertebral 6-nail internal fixation, i.e., screws are screwed into the fractured vertebrae and its upper and lower adjacent pedicles and vertebral bodies, and the ligaments are axially reset by establishing a fulcrum on the fractured vertebrae and longitudinally bracing the fractured vertebrae with its inferior adjacent vertebrae. Transforaminal internal fixation significantly increases the strength, stiffness and stability of the spine, which can better distribute the load-bearing stress of the internal fixation and reduce the loosening or fracture of the internal fixation, and effectively reduces the hanging effect and quadrilateral effect of the internal fixation, thus reducing the incidence of late-onset kyphosis. Some scholars have obtained spinal stabilization by lengthening the internal fixation segments (2 normal vertebrae above and below the injured vertebrae), but more spinal motion segments were lost, which led to poor outcomes. By placing nails on the secondary injured vertebrae, a fulcrum was established, which effectively increased the strength of the spine and dispersed the load-bearing stresses of internal fixation, while at the same time the fulcrum on the secondary injured vertebrae facilitated the bracing and resetting of the critically injured vertebrae, which had a significant effect on the resetting of the critically injured vertebrae and the correction of the deformity compared to the 4-vertebrae, 4-nail method. Our follow-up found that although there was no internal fixation breakage or loosening, there was a certain degree of loss of the degree of correction of the kyphosis of the key injured vertebra. Clinical thoracolumbar vertebral fracture CT scan found that the injured vertebral pedicle fracture rarely occurs, and in the combination of the pedicle and the posterior margin of the vertebral body is a good site for fracture, and vertebral body fracture occurs in the anterior and superior part of the vertebral body, while the middle and lower part of the vertebral body is more intact, so it can be seen that the transforaminal pedicle fixation of the injured vertebrae is theoretically feasible. Points of key injury vertebrae nailing 1) Before nailing the key injury vertebrae, we need to determine the degree of pedicle injury by CT, if the pedicle injury is serious and displaced, then it is not suitable for nailing. Before nailing, we emphasize the hyperextension position, so that the height and shape of the injured vertebrae can be restored to a certain extent, and a larger operating space is provided for nailing.2) The entry point of pedicle screws should be chosen outside the conventional entry point to avoid entering the spinal canal. Secondly, the screws should be 2 threads shorter than the screws in other vertebrae, and the screws should point to the anterior inferior angle of the injured vertebrae to avoid affecting the healing of the injured vertebrae, and to avoid increasing the holding force of the screws due to the excessive length of the screws, which would affect the effect of the repositioning. This is different from the method reported by Wang Shouguo et al. 3) The pedicle screw of the injured vertebra does not need to be completely screwed into the injured vertebra, but 2 turns of threads are reserved, and the curved anterior convexity of the pre-curved connecting rod is aligned with the opening of the tail cap of the injured pedicle screw and tightened to fix it, so that the injured vertebra can be topped anteriorly, and then, using the pedicle screw of the key injured vertebra as the pivot, the critical-injury vertebra-normal vertebra and key-injury vertebra-secondary-injury vertebra can be performed. The key injured vertebra – normal vertebra and the key injured vertebra – secondary injured vertebra were instrumented for internal fixation (a new pivot point for the fixation was established). By pushing the injured vertebra and compressing the posterior column, not only is the repositioning direct, but it can also achieve the purpose of lengthening the anterior column and shortening the posterior column, which is more in line with the biomechanical mechanism of the spine.