Experimental And Simulation Study Of Tensile Properties Of Lumbar Intervertebral Disc

In daily life,the lumbar intervertebral disc(IVD)is subjected to a compressive load,and is also subjected to a tensile load,such as playing badminton and swimming,which all makes the IVD of the human body is subjected to a tensile load.Due to its special location,it is more prone to injury or degeneration,leading to lumbar disc herniation.For slight lumbar disc degeneration,traction treatment is often used,but for patients with ineffective traction treatment,the method of nucleotomy is usually used.After the IVD degeneration and the nucleus pulposus removal,its material properties,mechanical environment and loading mode will change.So this paper studies the mechanical properties of normal and nucleotomy disc under tensile load from the experimental and simulation aspects,and the study results will provide theoretical basis for traction treatment of disc herniation and postoperative recovery of IVD.The experiments used fresh pig lumbar IVD as the research object.And the normal IVD was used as the control group,the degenerative and removed nucleus pulposus IVD was used as the experimental group.Digital image correlation(DIC)technique was used to study the axial and radial strain distribution rules of IVDs in different regions of the two groups of the sagittal plane under tension load.It found: in the posterior region of the IVD,the axial and radial strains of the annulus fibrosus(AF)were larger than that in the anterior region,and the inner AF were larger than that of the outer AF,and the experimental group strains were larger than control group.In order to compare with the axial strain under tensile load,DIC technique was used to study the axial strain distribution rules of the two groups of IVDs in different regions of the sagittal plane under compression load.It was found that: in the posterior region,the axial strain of the AF was larger than that in the anterior region,and the inner AF was larger than that of the outer AF,and the experimental group strain was larger than control group,this was consistent with the axial strain distribution of the disc under tensile load.The creep characteristics of IVDs under different load sizes and different loading rates were studied by applying tensile loads on the IVDs of the two groups.It was found that with the increase of tensile time,the strain of the two groups increased exponentially.When the loading rate was the same,the larger the tensile load was,the larger the strain was;when the loading load was the same,the larger the loading rate was,the larger the strain was;and the strain changes of experimental groups were larger than control groups.The ABAQUS software was used to simulate and analyze the normal and nucleotomy lumbar disc models of human body.The Mises stress contour map,creep curve map under different tensile loads,and the axial displacement cloud map,axial stress cloud map and creep curve under the combined effects of different loads were obtained.The results showed that the creep curves of both normal and removed nucleus pulposus IVDs were changed exponentially under different tensile loads,and after removing the nucleus pulposus,the strain of the IVD was greater than that of the normal disc,and which was consistent with the experimental results.The creep curves of IVDs under the combined effects of different loads all showed exponential changes.The initial growth rate of the intervertebral discs was faster,and the creep value remained basically unchanged after 1000 s,and after the removal of nucleus pulposus,the strain of the disc was larger than that of the normal disc.Under the axial tensile load,the experimental and simulation results show that the stress of the annulus fibrosus increases,indicating that under the action of tensile force,it is conducive to the shrinkage of the protruding intervertebral disc,which provides the corresponding theoretical guidance for the traction treatment of the disc herniation and the postoperative recovery of the disc.