Correlation Factors Of Intervertebral Disc Degeneration And Morphologic Differences Of Different Types Fracture In Healing Thoracolumbar Type A Fracture-one To Six Years Follow-up Study

Objective: To analyze morphologic differences of different types of thoracolumbar fracture after healing,and the correlative factors of intervertebral disc degeneration-1 to 6 years follow-up study.Methods: A retrospective study was conducted on thoracolumbar type A fracture patients from 2011 to 2016 in our department.The X-ray,CT and MRI examinations of thoracolumbar spine were performed before operation.All patients were treated with posterior open reduction and short-segment pedicle screw fixation.The internal fixation was removed after 8 to 12 months after the surgery.The MRI examinations of the patients’ thoracolumbar spine were obtained again for the next 3 to 56 months.MRI imaging was used to analyze the morphology of the injured vertebra,which is healed after the second operation,and the reposition of the endplate and signal changes of the vertebral disc.According to the AO classification and the degree of degeneration of intervertebral disc adjacent to the injured vertebral,the classification of fracture was assessed using Pfirrmann classification.The postoperative pain in patients’ lower backs and quality of life were evaluated according to visual analogue scale(VAS)and Oswestry disability index(ODI).We analyzed the correlative factors of the intervertebral disc degenerationand different types of healed vertebral by comparing the pre-operative and post-operative MRI results from 1-6 years.Results: 23 cases was completed which include 6 cases of type A1 fracture,2 cases of type A2 and 15 cases of type A3.In term of Pfirrmann classification,before the operation the discs of 9 cases were in gradeⅠ,35 cases in grade Ⅱ,2 cases in grade Ⅲ degeneration.After 1 to 6 years follow-up,there were 6 cases were in gradeⅡ,21 cases in grade Ⅲ,10 ingrade Ⅳ.It’s about 90% of discs showed varying degrees of degeneration.In the 6 cases of type A1 fracture,there were 5 cases collapsed in the central part of the vertebral body,besides,the disc adjacent to the fracture vertebral occurred degeneration.There were 15 cases of type A3 fracture vertebral malformation healed.Although the damaged endplate was unreposition and the intervertebral disc was inserted into the vertebral body,the disc adjacent to the fracture vertebral occurred obvious degeneration.There was no statistically significant between the sexes,the fracture type and disc degeneration(P > 0.05).There were statistically significant between the degree of intervertebral disc degeneration and the age of injury,the type of fracture and the follow-up time(P < 0.05).There were statistically significant between intervertebral disc degeneration and VAS and ODI(P < 0.05).VAS were significantly correlated with ODI.Conclusion: The degeneration happened in the vertebral disc which adjacent to the thoracolumbar vertebral fracture in the postoperative flow-up of 1-6years,which treated with posterior open reduction and short-segment pedicle screw fixtion.The degree of intervertebral disc degeneration was related to the patient’s age,fracture type and follow-up time.The central part of the vertebral body collapsed after the vertebral fracture of A1 type fracture.The endplate of the A3 fracture was unreposition,and the vertebral malformation healed.