EFFECT OF NUCLEOTOMY ON AXIAL AND RADIAL COMPRESSION STRAIN DISTRIBUTIONS OF INTERVERTEBRAL DISC

Abstract

Surgery of nucleus pulposus removal is one of the methods used for the treatment of lumbar disc herniation in the clinic. In order to understand the strain states of the lumbar intervertebral disc (IVD) after nucleotomy, the axial compression experiments of porcine lumbar IVD were implemented using digital image correlation (DIC) technology. The normal IVDs are named as control group; the IVDs treated with trypsin by removing the nucleus pulposus are named as experimental group. The distributions and the change rules of both axial and radial strains in different regions of the IVD with load were studied, and the experimental results of two groups were compared. The results show that both axial and radial strains of different regions increased with stress in two groups, and the variation had non-uniformity. The axial strain in the posterior region of the annulus fibrosus (AF) was larger than that in the anterior region, and the inner AF was larger than that of the outer AF. The axial strain increase of the experimental group was larger than that of the control group obviously. In the posterior region, the radial strain increase was larger than that in the anterior region, and the outer AF was significantly larger than that of the inner AF. The radial strain direction of the experimental group in the inner AF was towards the center of the nucleus pulposus, which was opposite to that of the control group, and the radial strain increase was evidently smaller than that of the control group. In the outer AF, the radial strain direction of the experimental group was the same as that of the control group and the radial strain increase was significantly larger than that.