[Abstract] Objective: To investigate the value of sphenoid lamina complex replantation and titanium plate fixation in the resection of intravertebral canal tumors. Methods From November 2009 to July 2010, 22 cases of intravertebral canal tumors were treated by grinding the vertebral plate on both sides along 2-3 mm of the medial aspect of the articular eminence, removing the sphenopalatine lamina complex intact, and then replanting the sphenopalatine lamina complex in situ and fixing the titanium plate after treatment of intravertebral canal tumors to complete vertebroplasty. Results: 20 cases of total tumor resection and 2 cases of subtotal resection. The number of laminae removed ranged from 3 to 5, with an average of 3.75. There were no complications such as dural rupture, spinal cord and spinal nerve root injury due to grinding and drilling of the spinal canal opening and titanium plate placement. At a follow-up of 3 to 12 months, with an average of 4.5 months, there was no displacement of the returned tissue, collapse, deformity healing or spinal stenosis, and no instability or deformity was observed. Conclusion, the use of grinding and drilling posterior spinal canal opening and titanium plate fixation of the spinous process lamina complex in intravertebral canal tumor surgery is simple, safe, reliable, and beneficial to the integrity and stability of the spine. [Keywords] grinding and drilling; titanium plate fixation; intravertebral canal tumor; stability The traditional posterior surgery for intravertebral canal tumor often performs sphenoidal laminectomy, which destroys the posterior structure of the spine and to a certain extent destroys the stability of the spine. In the literature, there are many reports of spinal deformity after surgery for intradural tumors, with an incidence of 21%-42%, which can occur within 1 year after surgery [1]. Therefore, the treatment of intravertebral tumors should pay attention to the protection of spinal stability. In recent years, some authors have used a bone knife to cut the spinous process lamina complex and silk or wire fixation for vertebroplasty, which has achieved the effect of protecting the stability of the spine. However, this method is slow and the reliability of fixation is poor. from November 2009 to July 2010, we used micro-drills to remove the entire sphenopalatine lamina complex in 22 cases of intravertebral canal tumors, and then reconstructed the posterior stability of the spine by resecting the tumors and replanting them in situ and fixing them with titanium plates, and achieved good results. 1, clinical data and methods 1.1, general data, the group of 22 cases, 12 men and 10 women. The age ranged from 21 to 65 years old, with an average of 38 years old. The disease duration was 2 months~5 years, with an average of 11 months. All of them had neurological symptoms and signs before surgery, including pain in 15 cases, numbness of limbs in 17 cases, a feeling of chest and abdominal banding or a feeling of stepping on cotton on the soles of the feet in 7 cases, and weakness of limbs in 12 cases. On examination, 3 cases had no obvious neurological signs, 14 cases had different degrees of hyperalgesia, 6 cases had hyperalgesia, 12 cases had decreased muscle strength of the limbs, 1 case had muscle atrophy of the upper limbs, 2 cases had increased muscle tone of the lower limbs, 8 cases had active tendon reflexes, and 6 cases had positive pathological signs. Preoperatively, MRI and CT scan were performed. The tumors were located in the cervical spine in 15 cases, the thoracic spine in 4 cases, and across the cervicothoracic segment in 3 cases. The length of tumors ranged from 3 to 11 cm, with an average of 4.3 cm. 12 cases were located in the intramedullary region, and 10 cases were located in the extramedullary subdural region and occupied more than 2/3 of the spinal canal. Selection criteria: ① those with intradural lesions using vertebroplasty; ② complete clinical and pathological data; ③ at least 3 months of postoperative clinical and medical imaging follow-up. Exclusion criteria: ①including those with anterior approach surgery; ②underage at the time of surgery; ③intraoperative destruction of small joints. 1.2. Surgical method, prone position, tracheal intubation with static suction compound general anesthesia. With the lesion as the center, a posterior median skin incision is made and the lesion is routinely exposed on both sides of the vertebral plate as well as the upper and lower portions of the vertebral plate adjacent to it. The supraspinous ligament, interspinous ligament, and ligamentum flavum between the spinous processes at the upper and lower ends of the spinous complex to be resected in its entirety are severed, and the above ligaments between the other spinous processes are preserved intact. The vertebral plate on both sides is ground away with a high-speed grinding drill along the medial side of the articular eminence 2 to 3 mm, with the drill angled slightly to the sagittal plane of the body and tilted laterally to grind away the vertebral plate, and the other side of the plate is ground away in the same way. Lift one end with a scarf clamp, cut the attached ligamentum flavum, peel away the epidural fat and possible adhesion bands with a nerve stripper, and remove the spinous process lamina complex for replantation after freeing. The tumor is removed under a microscope using a bipolar electric knife, microscopic instruments, and an ultrasonic aspirator. After completing the intradural surgery, the spinal canal is reconstructed and one end of the titanium plate is fixed to both sides of the free spinous lamina complex with miniature self-tapping titanium nails, and then the spinous lamina complex is put back in place and fixed to the lateral lamina site with titanium nails. The flexion of the titanium plate can be shaped as required to prevent the plate from invaginating and to bring the broken end of the plate as close as possible to the lateral block section (Figure 1). 2, Results Microscopic total resection was performed in 20 cases (nerve sheath tumor in 8 cases, ventricular meningioma in 6 cases, vascular reticulocytoma in 4 cases, and cavernous hemangioma in 2 cases), and subtotal resection was performed in 2 cases (spinal meningioma in 2 cases). The number of laminae removed ranged from 3 to 5, with a mean of 3.75. None of them had complications such as dural rupture, spinal cord and spinal nerve root injury due to grinding and drilling of the spinal canal opening and titanium plate placement. At a follow-up of 3 to 12 months, with an average of 4.5 months, an anatomical repositioning of the spinous process plate complex was achieved after X-ray and CT plain examination, and no graft displacement or collapse was observed (Figure 2), and no complications such as spinal deformity and secondary spinal stenosis were observed. The human spine is divided into anterior, middle, and posterior columns, and biomechanical experiments on the spine have confirmed that the posterior column structure is also important for maintaining spinal stability. The sagittal stability of the spine is maintained by the balance of anterior and posterior structures, and any change in the posterior bone or ligamentous structures of the spine may cause displacement of the weight-bearing axis. Laminectomy shifts the weight-bearing axis ventrally to the anterior portion of the vertebral body, leaving most of the weight to be carried by the anterior vertebral body and intervertebral discs; as the load increases, the anterior spinal column tends to be deformed in compression and the posterior column is in tension; because the posterior tension band has weakened, its power to counteract altered spinal alignment is reduced, which may cause changes in the spinal sequence. Conventional laminectomy requires occlusion of the spinous process, supraspinous ligament, interspinous ligament, and lamina to fully reveal the tumor, but it affects the biomechanical balance of the spine because it disrupts the posterior spinal structures. When the tumor segments are long, the posterior structures are more damaged, which can cause spinal deformity and seriously affect the patients’ life and working ability [1]. How to maintain the biomechanical stability of the spine has increasingly become the focus of neurosurgeons’ attention [2]. Moreover, the dura mater and nerve roots are not covered by bony structures, which can easily cause postoperative scar compression. In order to reduce the impact of laminectomy on spinal stability, many scholars have actively explored. Methods such as partial laminectomy with interlaminar openings can reduce damage to posterior spinal structures, but often have limited exposure, limiting the successful performance of the procedure. Microsurgical resection of intradural tumors with a hemi-laminar approach is characterized by less surgical trauma, faster postoperative patient recovery, and preservation of spinal stability, but is also limited in exposure and restricted to extramedullary tumors with lesions on one side and occupying no more than 2/3 of the spinal canal [3,4]. The disadvantage of single-opening vertebroplasty is the inability to reveal the portal axis side, as well as inadequate exposure of the spinal canal contents, which is also not conducive to surgical manipulation [5]. The ideal procedure should adequately reveal the spinal canal while ensuring the stability of the spine. In situ reimplantation of the spinopelvic complex allows for both, ensuring adequate intraoperative exposure while maintaining the integrity and stability of the spine postoperatively. Therefore, this procedure can be considered for larger extramedullary subdural occupancies and benign intramedullary tumors in the spinal canal. This technique has the following characteristics: (1) Adequate exposure of the intradural tumor allows for a variety of intradural procedures. (ii) Postoperative spinal curvature and mobility are stable because the posterior tension band is partially preserved, which reduces the occurrence of kyphosis or instability [4]. (iii) In the cervical spine axial symptoms can be reduced. ④Postoperatively, it can provide a more robust protection for the spinal canal contents, prevent medically induced spinal stenosis, and reduce accidental injury to the spinal cord [6]. ⑤ It can restore the normal anatomy of the posterior spine, preserving the ligamentous one-nerve-one-muscle neuroreflex system and facilitating the fine regulation of paravertebral muscle activity. Most of the currently reported surgical approaches use bone knife osteotomy. The bone cutter has less bone loss and is superior to the biting forceps, but the osteotomy speed is slower and the spinal cord is easily damaged by improper use. We applied the microdrill to the posterior spinal canal during the exposure procedure and confirmed that the microdrill can not only safely and rapidly grind away the spinous process lamina complex, but also reduce bleeding compared with bone knife osteotomy. During surgery, the drill is placed 2 to 3 mm medial to the articular eminence on both sides, too medial to expose enough, too lateral to easily enter the spinal canal, and easy to damage the intervertebral joints. A miniature drill must be used during surgery to minimize bone loss to facilitate postoperative bony healing of the vertebral plate. The grinding drill is slightly inclined to the sagittal plane of the body, which helps to prevent the intrinsic invagination of the spinous complex of the vertebral plate implanted back. In addition, when the vertebral plate is estimated to be nearly ground through during surgery, do not press down on the plate or the drill with force to avoid damage to the dura, spinal nerve roots, spinal cord, or spinal cord concussion. When removing the spinous process-plate complex, the dura should be carefully separated to avoid dural tears due to adhesions. None of the 22 cases we followed had complications such as dural rupture, spinal nerve root and spinal cord injury due to broken bone, proving that this procedure is safe and reliable. Some people have used a milling knife to cut through the vertebral plate and also achieved good results [7]. The purpose of the sphenopalatine plate complex replantation is to reconstruct the anatomical structure of the spinal canal and restore the integrity and stability of the spine. The most critical aspect of replantation is that it must be firm and reliable without sinking into the spinal canal, so it is important to choose a suitable fixation material. Especially in the thoracic spine, the spinal canal itself is relatively narrow and a small amount of bone is removed from both sides, which may aggravate the narrowing after fixation, which is not uncommon in clinical practice, thus requiring higher requirements for fixation materials. One of the commonly used fixation methods in the past is to fix the vertebral plate with a ligature of 10 wires, which is not strong enough and has a high possibility of loosening and displacement after surgery, resulting in non-healing or delayed healing of bone graft; the second is bio-adhesive, but it is difficult to meet the stress requirements of the spine; the third is steel wire, which has a good fixation effect, but if it breaks and falls off into the spinal canal, it will cause serious consequences, and also limits the application of MRI and other The application of auxiliary examination means. Although the fixation effect of the commonly used nail bar system in orthopedics is exact, it affects the local mobility, aggravates the degeneration of the adjacent segments, and also affects the application of MRI. We have received excellent results by using titanium plates and nails to fix the spinous process lamina complex. It is simple to operate under direct vision, easy to shape, firm fixation, and no subluxation of the vertebral plate. The segmental fixation method is adopted, and the spinous lamina complex is fixed to the articular eminence with titanium connecting plates (2 or 4 holes) and self-tapping titanium nails (2~4 on each side) on each side of the spinous process of each vertebral plate segment. The effect of limited spinal mobility after overall fixation and fusion is avoided. The screws are inserted perpendicular to the bone surface, which prevents the screws from entering the spinal canal, and postoperative MRI is not affected by the use of titanium nails. In our group of 22 patients followed up from 3 to 12 months with an average of 4.5 months, no collapse of the replanted spinous lamina complex into the spinal canal, kyphotic deformity of the spinal canal, or medically induced spinal stenosis was observed, and there was no dislodgement or displacement of the inserted material. In the literature, a transtentorial screw fixation method is also used, in which a screw is nailed from the root of the contralateral spinous process according to the preoperative angle measurement, and the spinous complex is repositioned and fixed in the direction of the superior articular eminence on the fixed side [8]. This method has a long nail path and firm fixation, but it is mainly used in the thoracic and lumbar spine; and there is a possibility that the screws may enter the spinal canal if the direction of nailing is not precise during the operation. In order to prevent the retraction of the retraction plate into the spinal canal after spine laminar complex reimplantation, attention needs to be paid to reducing bone loss in addition to firm fixation. Therefore, a microdrill should be used during the procedure to reduce the amount of bone abraded. The less bone loss and the wider the preserved vertebral plate, the more adequate the contact of the section during replantation and the more favorable the formation of bony healing. It has been reported in the literature that less bone is lost when a special wire saw is used for laminectomy [9]. It has also been reported in the literature that the spinous process is removed in its entirety in the thoracolumbar spine, and the spinous process and one side of the plate are repositioned and fixed instead of the original bilateral plate after rotation in the horizontal plane. Since the spinous process is well preserved and longer than the unilateral plate, part of the spinous process can be ground off and reimplanted according to the size of the operative window to make it suitable for the size of the operative window, which is more conducive to bony healing and prevents the reimplant from sinking into the spinal canal [10]. If the spinal canal is already stenosed before surgery, the titanium plate can be shaped in flexion and the “elevated bridge” graft can be used to enlarge the spinal canal. This procedure provides adequate exposure for resection of spinal canal tumors and is particularly useful in cases of multisegmental lesions and benign intramedullary lesions. The procedure is also advantageous because it is easy and safe to fix intraoperatively under direct vision, with reliable fixation, good bone confrontation at the trabecular edge, easy fusion, and no restriction of spinal mobility after fusion. After fixation with full laminar spinous complex coverage, ideal anatomical repositioning can be achieved, and the integrity of the spine and spinal canal can be reconstructed, avoiding complications associated with laminectomy. The good postoperative fusion of the back implant increases the stability of the spine and reduces many complications due to postoperative spinal instability. This shows that this procedure can meet the need for surgical exposure while maintaining the integrity of the spinal canal, preserving the stability of the spine, and preventing postoperative muscle-dural adhesion scar formation to compress the spinal cord. However, the maintenance of spinal stability by this method needs to be studied in a large number of cases with long-term follow-up.