The Biomechanical Evaluation Of Single-intervertebral-space By Anterior Instrumentation In The Treatment Of Thoracolumbar Fracture

Background:With the development of the production , the incidence of spinal fracture is increasing . The fracture often occures in thoracolumbar spine , and the most majority of a single-vertebral-fracture , and its high incidence about 60 / million, accounting for the body fracture 5% -6%. As most of the patients with spinal fractures would result in paralysis , incontinence and high disability; And the current surgery way to cure the fracture are more defects, such as injure the upper and lower vertebral on the normal fixed, reduce the normal activities of the spine, arise to surgical trauma and hemorrhage when to reduct and fix the injury vertebrae. So, in order to improve the treatment of spinal fractures, reduce the surgical trauma and bleeding complications, we use the single-intervertebral-space fixation for an initial try on the thoracolumbar fractures by anterior . At the moment , the current method of spinal surgery divide into the posterior fixation and the anterior fixation, and posterior fixation of single-intervertebral-space has been reported, but the anterior has not reported yet.Objective:The experment is to study the surgery way of spinal fractures model made by fresh porcine spinal segments and use one the single-intervertebral-space fixation and other the double-intervertebral-space fixation to reduct the fracture. Comparison of the two fixation methods in the different of biomechanical. Comparison of two surgical procedures on stability immediately after the surgery.Methods:The experiment is study on the T10 to L3 spinal segment of porcine spinal bone , the total are 10. Use the spine testing machine to measure the Vertebral T12 TO L2 (load 0 Nm～4.0 Nm), impose on the specimen each other through a pair of size equal to the opposite and effect the torque on the specimen. Each specimen has four kinds of motion states , the intact, the injured, the single-intervertebral-space fixation and the double-intervertebral-space fixation. So that the specimen has a ability to flexion, extension, left bending and left axial rotation. Take the spinal motion picture at zero load (0 Nm)and the maximum load (4.0 Nm) by the 3D laser scanner. Analyse the image by the software system, calculate the range of motion of T12 to L2. Use statistics software SPSS13.0 , data for each group analyse by the randomized block analysis of variance (least-significant difference, LSD method) each other, set the level of significance (P<0.05).Results:1. According to the test, the ROM of single-intervertebral-space fixation had a significant in the motion states of flexion, extension and left bending , compared with the infact and the injured (P<0.05).2. The ROM was no significance at the axial rotation by the single-intervertebral-space fixation and the double-intervertebral-space fixation compared with the infact (P>0.05).3. The ROM was no significance at the four motion states by the single-intervertebral-space fixation and the double-intervertebral-space fixation (P>0.05).Conclusion:1. Compared with the infact and the injured, the surgery manner of the single-intervertebral-space fixation and the double-intervertebral-space fixation not only to return to the stability of the spinal at the motion of flexion, extension and left bending,but also to enhance the stability of the spinal.2. Compared with the infact, the surgery manner of the single-intervertebral-space fixation and the double-intervertebral-space fixation had the ability to return to the stability of the spinal at the motion of flexion , but had no ability to enhance the stability of the spinal.3. There was no significance at the four motion states by the single-intervertebral -space fixation and the double-intervertebral-space fixation to show that the two fixation methods are close in the ability to rebuit the stability of spinal.4. On the base of present theory and the experiment results, we should be cautious that the effect of surgery by the single-intervertebral-space fixation is close to the double-intervertebral-space fixation, the former surgery manner has the advantage in reducing the surgical trauma , reducing the occurrence of ASD, reducing the ischemia of the spinal cord.