After general tracheal anesthesia, the fractured and adjacent vertebral pedicles are identified under C-arm fluoroscopy of 6 pedicle projections, and an intact pedicle of the injured vertebra is fitted with screws (preoperative computed tomography scan), and the entry site to the pedicle is located at the junction between the lateral border of the superior articular facet and the bisecting midline of the transverse process. Once the pedicle is identified, a pedicle probe is used to enter the pedicle, and preoperative anteroposterior and lateral roentgenograms and computed tomography (CT) scans through the pedicles of the vertebral body to be instrumented are assessed to determine the optimal angle of entry in both the coronal and sagittal planes. Pedicle integrity is verified in all five quadrants to ensure the presence of a solid tube of bone and that violation of the spinal canal or inferiorly into the neuroforamen has not occurred. The tip of the needle is positioned at the 10 and 2 points of the left and right pedicle. The puncture angle (anteroposterior, introversion angle 10°–15°) is determined and five hollow pedicle screws are torqued in. C-arm fluoroscopy is activated again and the tip of the screw is positioned in the front one-quarter to one-third of the vertebral body to confirm that the position is satisfactory. One side of the three screws is fixed first, and then the screws are torqued in and the nuts are tightened. The order of fixation is injured vertebra, lower vertebrae, and upper vertebrae. According to the degree of compression of the injured vertebra before the operation, the reduction should be performed between the injured vertebra and the upper vertebra. Fluoroscopy is used to confirm that the working channel enters the front one-third of the injured vertebra. A bone cement injection tube with an inner core is inserted. After mixing the bone cement to the dough stage, it is injected under fluoroscopic guidance. When the bone cement flows backward and approaches the posterior edge of the vertebral body, the injection is immediately stopped. The side connecting rod is fixed and C-arm fluoroscopy is activated to confirm satisfactory positioning of the implant, and the skin is sutured.
Antibiotics were routinely administered to prevent infection, with standing or walking under the protection of a thoracolumbar brace for 2 weeks after the operation, with the lumbar brace removed 1.5 months after the operation.
The following clinical indexes were observed and recorded: operation duration; surgical blood loss; amount of cement instillation; and number of cement leakages. A visual analog scale (VAS) was used to evaluate back pain. VAS pain assessments were performed immediately, preoperatively, at 3,14 days, at 1, 3, 6,12 months and the final follow-up after surgery. The Oswestry disability index (ODI) was used to evaluate functional outcome, the plain radiographs were captured preoperatively, immediately postoperatively, and at the final follow-up. The following parameters were observed and analyzed: local kyphotic angle, defined as the angle measured between the superior endplate of the upper vertebra and the inferior endplate of the lower vertebra; and percentage of anterior height of the fractured vertebra. The anterior height of the fractured vertebra was defined as the anterior height of the fractured vertebra divided by the normal anterior height of the vertebra. Cobb angles and anterior vertebral body height were measured on lateral radiographs. The fractured and restored heights were calculated as a percentage of the estimated intact vertebral body height by averaging the anterior height from the adjacent levels.
Data are expressed as mean ± standard deviation (SD) and were analyzed using SPSS version 22.0 (IBM Corporation, Armonk, NY, USA). The paired Student’s t-test and Dunnett’s t test were used to evaluate changes in data at different times, and the VAS score, Cobb angle in the sagittal plane, and anterior height ratio of injured vertebrae were assessed using X-ray. The anterior vertebral height ratio and sagittal Cobb angle at different time were compared using repeated measures analysis of variance. Pairwise comparisons at different times after the operation were performed using Dunnett’s t test; differences with p < 0.05 were considered to be statistically significant.