The Results Of Thoracolumbar Burst Fracture Treated With Pedicle Screw Instrumentation

[Objective]To evaluate the results of thoracolumbar burst fracture treated with short-segmentpedicle screw system and to analyze the treatment outcomes as well as its correlationfactors.[Methods]Thoracolumbar burst fractures that were operated at our department during 1998 to2005 were followed up. 64 cases that had integrity data were analyzed. The radiographic,neurological, and functional outcomes were assessed. All of the cases were checked withradiography pre-and post-operation, before implant removal, and at final follow up.Anterior and posterior vertebral height of the fractured vertebral body, vertebral body angle,Cobb angle and sagittal index were measured at the lateral X-ray plains. The Mimura'sradiographic system for grading disc degeneration was used. 32 cases performed the axialCT scan and sagittal-coronal reconstruction at last follow-up, We measured the narrowingof midsagittal diameter of injured segment. 12 cases that were followed up more than 5years were performed MRI examination at the. final. Neurological status was assessedpre-operation and final follow up using the Frankel Scales. Patient's pain and back statuswere assessed using the Denis Pain Scale and Oswestry Disability Index (ODI).[Results]After post-operation, AVH were restored from 55.2%±415.1% to 97.2%±.8.1%, PVHfrom 88.9%±6.1% to 99.1%±5.0%, VBA from 20.3°±7.2°to 2.6°±4.0°, Cobb angel from18.9°±10.1°to 0.5°±8.9°, SI from 18.9°±7.2°to 2.1°±5.0°. After pedicle screwinstrumentation to implant removal, the losses were that, AVH 3.2%±2.6%, PVH2.1%±2.2%, VBA 2.0°±1.3°, Cobb angle 2.8°±1.3°, SI 2.0°±1.1°. After implant removal tofinal follow up, the losses were that, AVH 5.1%±4.6%, PVH 3.3%±2.8%, VBA 3.2°±2.5°, Cobb angle 6.9°±2.5°, SI 5.7°±4.5°.There was significant deference in targets (AVH, PVH, VBA, Cobb, SI) betweenpre-operation and post-operation (P＜0.01) , before implant removal and post-operation(P＜0.01), before implant removal and at final follow up (P＜0.01). The injured discspaces degenerated at final follow up. MRI examination demonstrated this change clearly.There was significant difference in the narrowing of midsagittal diameter of injuredsegment between pre-operation and at final follow up (P＜0.01), the spinal canal diameterwas enlarged significantly.At the final follow-up, all of the patients' neurological status was Frankel A in 3 cases,C in 3 cases, D in 6 cases and E in 52 cases. There were still 12 patients suffering sphinctermuscle functional impairment. Neurological status improved at least 1 Frankel grade inpatients who had preoperative incomplete paraplegia, while no improvement was obtainedin those who had preoperative complete paraplegia. According to Denis Pain Scale, 28cases were P1, 29 cases were P2, 6 cases were P3 and 1 case was P4. Of the 52 patientswhose neurological status were E, the average ODI score was 15±17, 40 cases wereexcellent, 7 cases were good, 5 cases were poor. The correlation variables of ODI scorewere pre-operative AVH(B=-0.075, P=0.045) , last AVH(B=-0.100, P=0.043), painscale(B=2.443, P=0.012). Complications are rare, there were 6 cases occurredinstrumentation breakage in 64 cases, 32 cases that performed CT scan examinationshowed there were 4 pedicle screws misplaced in 128 screws.[Conclusion]Short-segment pedicle screw systems are successfully used in treating thoracolumbarburst fracture. It can restore vertebrae height, correct local kyphosis. Patients with none orminimal neurological deficits were treated with indirect decompression with pedicle screwinstrumentation, though indirect reduction technical achieve spinal canal decompressiononly. No laminotomies or partial laminectomies were performed. Direct decompressionassociated with partial laminectomies and posterior bone graft was performed in thepatients that had obvious neurological deficits. Spinal canal decompression was effective.Spinal stability was reconstructed. After pedicle screw instrumentation, the reduction lossoccurred, most at the injured disc space, vertebral height loss was minimal. Degeneration and narrowing was occurred at the injured discs. Neurological status improved at least 1Frankel grade in the patients who had preoperative incomplete paraplegia, while thepatients with complete paraplegia had no improvement. Recovery of conus medullarisimpairment was not satisfactory. Most patients' pain and back function were satisfactory.The pre-operative AVH, last follow-up AVH and pain scale were the correlation variablesof ODI value. Complications are rare, which chiefly consisted of instrumentation breakageand screw misplacement.