Osteoporosis is characterized by low bone mass and microstructural destruction of bone tissue, increased bone fragility, and easy fracture from minor injuries, with vertebral fracture being one of the best sites of incidence. Traditional conservative treatment is prone to complications such as crushing pneumonia and venous thrombosis due to the need for prolonged bed rest; vertebroplasty has achieved good results in treating vertebral compression fractures in osteoporosis, but this treatment is a relative contraindication for patients with osteoporotic vertebral burst fractures, especially those requiring spinal canal decompression; simple pedicle screw repositioning and fixation technique Because of the combination of osteoporosis patients are more likely to cause screw loosening or even extraction and internal fixation failure, later easy to occur reset loss, progressive retroconvex deformity, etc., reported as follows. (1) Clinical data: There were 11 cases in this group, 3 males and 8 females, age 52-69 years old, average 56.1 years old. The history of trauma was clear. There were no major underlying diseases in the past. The T-values were less than 2.5 standard deviations of the standard, and the clinical diagnosis was osteoporosis. Preoperative routine frontal and lateral spine radiographs, CT and MRI showed the injured spine: one case in the thoracic spine, eight cases in the thoracolumbar segment, and two cases in the lumbar spine; all were single-segmented. All patients had varying degrees of low back pain, 5 cases with neurogenic symptoms, ASIA score of neurological function: grade B in 1 case, grade C in 1 case, grade D in 3 cases, 11 cases with significant kyphotic deformity, CT showed that the posterior wall of the vertebral body was broken into the spinal canal and the spinal canal was occupied by 15-70%, X-rays or MRI indicated that the preoperative vertebral body was compressed by 45% on average (37-81%), and Genant semi-quantitative vertebral fracture The Genant semi-quantitative vertebral fracture analysis was grade III. (2) Preoperative preparation: Anti-osteoporosis treatment with calcium, osteotriol and salmon calcitonin, “triple” drugs. The patient was also treated with cardiac and lower extremity vascular ultrasound, pulmonary function tests and comprehensive physical examination, and intensive treatment of medical comorbidities such as hypertension, diabetes mellitus, anemia, chronic bronchitis, etc., and routine iodine allergy testing. (3) Operation method: The patient was given general anesthesia, the injured vertebra was located by C-arm X-ray machine, the posterior median spine incision was made to reveal the injured vertebra and the articular processes of the superior and inferior vertebrae, the “herringbone crest” positioning method was accurately positioned (assisted by C-arm fluoroscopy if necessary), the adjacent vertebrae above and below the injured vertebrae were drilled through the pedicle, and a tap with a diameter slightly smaller than that of the proposed screw was used. Tapping, the probe is repeatedly checked to ensure that the nail path is not broken, and if necessary, a contrast agent can be injected and judged by surveillance images. A 10 ml syringe is used to inject the bone cement (polymethyl methacrylate, PMMA from Stryker) into the vertebral body and the pedicle through the cannula, and the injection is stopped at 0.5 cm from the nail entry hole while withdrawing. The whole process was carried out under the supervision of C-arm X-ray machine, and the patient’s vital signs were closely monitored. The U-slot of the screw was adjusted so that it was in a straight line, and if necessary, pre-installation with a trial mold stick was used, and the overflowing bone cement was removed immediately. After the C-arm fluoroscopic repositioning is satisfactory, a nail bar coupling device is installed, the posterior lateral allograft or autologous bone graft is fused, a drainage tube is left in place, and a suture is applied. (4) Postoperative treatment: Observe the sensory movement of both lower limbs, prevent infection for 3 days with postoperative antibiotics, prevent thrombosis with low molecular heparin sodium, leave the bed under the protection of brace for 3-5 days after surgery, and review X-ray or CT film. Calcium, osteotriol, salmon calcitonin, and the “triple” anti-osteoporosis treatment for six months. Postoperative follow-ups were conducted at 1, 3, 6, 9, 12 months and every six months thereafter. (5) Evaluation method: Pre-operative, immediate post-operative and follow-up X-ray examinations of the thoracolumbar spine were performed, and the changes in the sagittal Cobb angle and sagittal index (SI = anterior height/posterior height of the injured vertebrae × 100%) were measured and calculated at different time points. Preoperatively and postoperatively and at follow-up all patients underwent ASIA grading statistics, simplified McGill (short-form of McGill pain questionnaire, SF-MPQ) pain questionnaire (including PPI, PRI and VAS scores) and Oswestry dysfunction index (ODI) version 2.0 Chinese version for satisfaction evaluation of surgical outcomes. (6) Statistical analysis: All data were analyzed and processed using SPSS11.5 statistical software, and the results were expressed as ±s. The t-test was used for comparison between two groups. 2. Results (1) All 11 patients were followed up for 7~42 months (average 27 months), all patients had one stage of wound healing, no 1 case of wound redness, infection and non-healing occurred, and no serious complications occurred. The average operating time was 92.7±5.3 min, and the average blood loss was 270±6.1 ml, with a total of 4.5-5.3 ml of self-curing bone cement injected into the pedicle nail tract, with an average of 5.1 ml. neurological symptoms. (2) In all cases, the internal fixation was not removed at the time of follow-up, and no fracture or screw dislodgement occurred. The SI values of injured spine height and injured spine Cobb angle were significantly improved in each group of patients after surgery and at follow-up compared with those before surgery (P1<0.01), and there was no significant difference between postoperative and follow-up (P2>0.05). See Table 1 (3) Survey of patient satisfaction rate and objective evaluation of clinical efficacy All 29 patients were followed up, and the ASIA scores of neurological function: preoperative grade B in 1 case to grade D, grade C in 1 case to grade E, grade D in 2 cases to grade E, and grade D in 1 case with no change, with very few patients feeling recurrent symptoms at the final follow-up, with a mean SF-MPQ score of 4.45, a mean VAS score of 2.1, and The mean ODI score was 19.3%, but the difference was not statistically significant when compared with postoperative (P>0.05). Bone density values increased slightly after surgery and at follow-up, but there was no statistical difference compared with preoperative values. 3. Discussion (1) Treatment of vertebral burst fractures with osteoporosis: for vertebral compression fractures of grade I and II, percutaneous vertebroplasty (PVP) or balloon kyphoplasty (PKP) can achieve better pain relief and partial correction of vertebral body loss height. However, for severe vertebral compression fractures or vertebral burst fractures, especially those requiring spinal canal decompression, are considered relatively contraindicated. In such patients, posterior simple arch nail repositioning and internal fixation open surgery can achieve satisfactory repositioning and correction of the posterior convexity deformity, but due to the patient’s reduced bone density, it is very easy to cause the fixation nail to loosen or even pull out, resulting in internal fixation failure. Anterior surgery can directly reconstruct the stability of the anterior mid-column, but this procedure is riskier for elderly patients, especially those of advanced age, and the average operation time, bleeding volume and risk are higher than those of posterior surgery. In recent years, although the biomechanical study of the effect of bone cement on the reinforcement of pedicle screws has been intensified, and there are more biomechanical reports on the application of bone cement to strengthen pedicle screws in recent years, the practice of clinical strengthening of screws is lagging behind and less carried out, and the main problem is that the leakage of bone cement cannot be completely eliminated, and once it occurs, the sensory and motor impairment occurs in mild cases, and pulmonary embolism in severe cases, which is life-threatening, so we We summarized the previous experience and lessons learned and improved the surgical technique to treat osteoporotic vertebral burst fractures in this group, and achieved better results. (2) The importance of perioperative osteoporosis drug therapy: The guidelines for the treatment of osteoporosis point out that the surgical treatment of vertebral fractures should be accompanied by anti-osteoporosis drug therapy, and the combination of osteoporosis drug therapy is desirable, with calcium, vitamin D and bone resorption inhibitors (bisphosphonates or calcitriol) constituting a “triple” drug therapy. Currently, the more recognized treatment plan. Although the bone mineral density of this group of cases did not increase significantly after drug treatment, the drug treatment obviously prevented the further decrease of bone mineral density, which indicates that the perioperative application of osteoporosis drugs is extremely necessary. (3) The effect of cement-enhanced screw fixation on spinal stability: The factors closely related to the stability of pedicle screws are the quality of the placed screws, the screw-bone interface and the screw connection, among which, the key is the screw-bone interface. The mechanism of bone cement for the strengthening of pedicle screw fixation is twofold: like artificial joints, bone cement has a certain anchoring effect between the screw and the bone; when the screw is screwed into the nail channel, the bone cement is extruded into the bone around the screw, and the strength of the surrounding bone is strengthened after curing. Experimental studies have shown that the use of PMMA can immediately increase the screw extraction resistance by 95% and 196% when added under pressure. Although it cannot be absorbed in vivo, it has a higher strengthening effect than calcium phosphate cement (CPC), calcium sulfate cement (CSC), hydroxyapatite (HA) and various biocomposites. stability, especially the immediate stabilization effect, which facilitates intraoperative repositioning of the pedicle, and significantly increases the fatigue resistance of the fixed spinal segments, resulting in durable and strong internal spinal fixation in patients with osteoporosis. From the follow-up results of this group, the arch nailing system combined with PMMA nail tract infusion is effective for vertebral body repositioning, with low risk of internal fixation fracture, dislocation and failure, and insignificant loss of vertebral body height after correction. (4) Surgical techniques and postoperative precautions: ① the operation must be performed under C-arm X-ray machine fluoroscopy; ② the depth of cement injection guide pin is generally at the junction of the middle and front 1/3 of the vertebral body; ③ for the central endplate with collapsed fracture, the curved guide cone should be used to pry combined with longitudinal bracing, so that the central endplate can be reset as far as possible; ④ when injecting cement in the nail channel, the cannula should be withdrawn while injecting to 0.5 cm from the entry hole The whole process of injection should be carried out under the supervision of C-arm X-ray machine, and the patient’s vital signs should be closely monitored; ⑤ It is recommended to use a slightly smaller diameter tap for tapping before nail placement, which not only increases the amount of cement placement and reduces the possibility of cement spillage caused by rupture of the pedicle, but also reduces the amount of cement spillage from the mouth of the nail during screw placement by forming a closed structure between the nail and the thread of the nail. (6) The use of a transverse joint device is emphasized. Biomechanical tests have shown that the use of a strong straight connection between the screw and the connecting rod with a transverse connection device can improve the relative stability of screw fixation in osteoporosis. Because the rod system instrumentation with tonic connection between the screw and connecting rod, together with two transverse connection devices, connects the whole instrumentation into a solid whole, which is equivalent to locking plate screw fixation, with good anchoring force and pullout resistance, and also improves the torsional force and fatigue resistance stability of the instrumentation. ⑦Patients are advised to wear the brace for at least 1 month after surgery; ⑧Due to the patient’s age, if there is no obvious fracture or loosening of the pedicle screw, it is not recommended to remove the internal fixation device; ⑨Adhere to the postoperative osteoporosis medication and diet regulation to slow down the process of osteoporosis as much as possible.