The Value Of MRI Grade Of PLL Injury To The Operation Choice In Thoracolumbar Burst Fractures

With the development of the economy,the incidence of spinal trauma increased year by year.Burst fractures contribute to approximately 10–20%of such injuries,and 50%of which accompanied by neurological damage^[1].In the1980s,Vidal proposed to use posterior external fixation to prop open the posterior longitudinal ligament to reduce the bone fragments protruding into the vertebral canal^[2].With the development of internal fixation materials,posterior surgery and reduction with posterior longitudinal ligament is the main treatment for thoracolumbar burst fractures.Some scholars believe that direct decompression is needed when the fracture block occupying exceeds50%^[3].Some scholars also believe that the simple degree of occupation in the spinal canal cannot be used as an indication of direct decompressio^[4].Although researchers hold so many opinions,when the patients do not need direct spinal canal decompression is still unknown.Objective:To explore the significance of MRI grading for posterior longitudinal ligament injuries in guiding surgical methodsMethods:A retrospective analysis was performed on 41 cases of thoracolumbar burst fractures with intraspinal bone mass occupying more than 50%treated in our hospital from March 2013 to March 2018.To study the MRI grade of PLL injury and the intraoperative findings.Measured parameters:Percentage of the canal（PC）,anterior vertebral body compression ratio（AVBCR）,Cobb angle（CA）.ResultsAll patients were followed up.One patient developed vertebral height loss,while the other did not develop related complications.All the 41 patients were treated with distraction and reduction surgery,among which 17 patients were found with unsatisfactory reduction during the operation,going with laminectomy,direct decompression and exploration of the posterior longitudinal ligament.The posterior longitudinal ligaments were ruptured.By comparing the preoperative magnetic resonance imaging（MRI）,9 of 24patients with indirect reduction were classified as gradeⅠinjury.The rest patients were classified as gradeⅡinjury.17 patients with direct decompression were classified as gradeⅢinjury.It consistent with intraoperative findings.There were statistically significant differences in the parameters of all patients before and after surgery.（P<0.05）The improvement rate of vertebral canal volume in patients undergoing indirect reduction was32.50±10.32%,and that in patients undergoing direct decompression due to poor reduction was 35.18±8.07%,with no statistically significant difference between the two groupsConclusion:The MRI grade of PLL injury can provide important message to the choice of operation in thoracolumbar burst fractue.Patiens with GradeⅠand gradeⅡPLL injury can be well decompressed with indirect decompression.Patients with GradeⅢPLL injury is recommended with laminectomy and lateral posterior transpedicular decompression.