| ObjectiveThe three-dimensional finite element analysis was used to observe the biomechanical effect of the spinal manipulation bed simulating the South Shaolin Daogaijinbei Manipulation on the degenerative L4-5 disc with different pushing heights,which provides a certain objective biomechanical theoretical basis for the clinical application of spinal manipulation bed simulating the South Shaolin Daogaijinbei Manipulation on the degenerative disc.Method1.Determination of pushing height:Using DR machine to take the picture of the lumbar lateral section before and after the simultaneous pushing of L4 and L5 spinous process by the Daogaijinbei Manipulation,and the measurement shows that the displacement change of L4and L5 is about 10cm,so the pushing height is set to 0~10cm.2.Acquisition of lumbar CT image and MRI image:A healthy volunteer's T12-S1 segment was scanned with Siemens 16 row spiral CT machine to obtain the lumbar CT image;the volunteer lumbar was scanned continuously with Siemens 3.0T MRI to obtain the lumbar MRI image.3.Establishment of normal lumbar model:Based on the CT and MRI images of the lumbar vertebrae of volunteer,the three-dimensional finite element model of the whole normal lumbar was established by the finite element modeling software such as Mimics 16.0,Geomagic Studio2014,Hypermesh 13.0,MSC.Patran 2012 and so on.4.Validation of the effectiveness of the lumbar model:A vertical load of 400N with a torque of10N.m was applied to the upper surface of the L1 vertebral body in the model to simulate forward bending,backward extension,left and right side bending,left and right rotation and other conditions,and the range of motion of lumbar was measured under different conditions to verify the accuracy and effectiveness of the lumbar finite element model compared with the calculation results with the published literature results.5.Establishment of degenerative lumbar disc model:Combined with previous studies,the disc height and nucleus area of lumbar disc were adjusted on the basis of normal whole lumbar disc model to establish the models of L4-5 disc with mild,moderate and severe degeneration.6.Biomechanical analysis of L4-5 disc:According to the operation characteristics of the spinal manipulation bed simulating the South Shaolin Daogaijinbei Manipulation,the 100N load is applied perpendicular to L4 and L5 simultaneously on the established three-dimensional finite element model of normal lumbar spine and degenerative lumbar spine,and 11 kinds of pushing heights(0cm,1cm,2cm,3cm…10cm)are simulated and the stress distribution of the lumbar intervertebral disc under different pushing heights was calculated and compared by using MSC.Nastran 2012 software.ResultIn this paper,the three-dimensional finite element model of normal lumbar spine is established based on the CT and MRI images of normal lumbar spine,and the finite element model of degenerated L4-5 disc is obtained by adjusting the parameters of the finite element model of normal lumbar.The changes of the stress of L4-5 discs and the size of L4-5 intervertebral foramen of different degeneration grade with different pushing heights are calculated and analyzed.The results are as follows:1.The stress of L4-5 normal disc,slightly degenerated and moderately degenerated discs showed a state of continuous growth when the pushing height was 0-8cm and a state of slow stability when the pushing height was 8-10cm,while the stress of L4-5 severely degenerated discs showed a state of continuous growth when the pushing height was 0-10cm.2.With the pushing height of 0-10cm,by comparing the normal group,the mild degeneration group,the moderate degeneration group and the severe degeneration group,changes of the peak stress of the L4-5 disc are as follows:The stress of L4-5 normal disc was 0.85Mpa-6.82Mpa,and compared with the stress of L4-5 normal disc,the stress of L4-5 disc with mild degeneration increased by 0.85-6.82%,and the stress of L4-5 disc with moderate degeneration increased by16.07%-30.32%,and the stress of L4-5 disc with severe degeneration increased by 31.10%-41.06%.3.The stress of the anterior,posterior,left and right of the fibrous ring and nucleus pulposus extracted from L4-5 disc were analyzed.The results showed that:(1)The stress of the anterior of the fibrous ring in the normal L4-5 disc was 0.82MPa~3.88MPa,and that in the L4-5 disc with mild degeneration,moderate degeneration and severe degeneration were 0.74MPa~3.52MPa,0.97MPa~4.31MPa,and 1.08MPa~5.39Mpa respectively;(2)The stress of the posterior of the fibrous ring in the normal L4-5 disc was is 0.22MPa~1.19MPa,and that in the L4-5 disc with mild degeneration,moderate degeneration and severe degeneration were 0.23MPa~0.97MPa,0.23MPa~0.79MPa and 0.45MPa~2.25MPa respectively;(3)The stress of the left of the fibrous ring in the normal L4-5 disc was 0.35Mpa~1.49Mpa,and that in the L4-5 disc with mild degeneration,moderate degeneration and severe degeneration were 0.45MPa~1.93Mpa,0.53MPa~1.95MPa and 0.72MPa~2.71MPa respectively;(4)The stress of the right of the fibrous ring in the normal L4-5 disc was 0.41MPa~1.78MPa,and that in the L4-5 disc with mild degeneration,moderate degeneration and severe degeneration were 0.51MPa~1.94MPa,0.60MPa~1.95MPa,and 0.63MPa~2.24MPa;(5)The stress of the nucleus pulposus in the normal L4-5 disc was 0.65MPa~1.18MPa,and that in the L4-5 disc with mild degeneration,moderate degeneration,and severe degeneration were 0.68MPa~1.30MPa,0.68MPa~1.18MPa,and 0.54MPa~1.35MPa respectively.4.The size of L4-5 intervertebral foramen was analyzed from the height and area of intervertebral foramen,and the results showed that:(1)The L4-5 intervertebral foramen height of normal lumbar,lumbar of L4-5 disc with mild and moderate degeneration,during the pushing process,was 20.1mm~25.9mm,18.4mm~24.9mm,14.5mm~20.2mm respectively,and the area of L4-5 intervertebral foramen is 235.2mm~2~341.9mm~2,199.9mm~2~313.3mm~2,166.8mm~2~253.6mm~2 respectively.And,the height of L4-5 intervertebral foramen and area are increasing in the process of pushing 0-8cm.After the pushing height reaches 8cm,the height of L4-5intervertebral foramen and area are gradually stable;(2)As for L4-5 disc with severe degeneration,during the pushing process,the height of L4-5 intervertebral foramen is 9.1mm~10.2mm,and the area of L4-5 intervertebral foramen is 121.6mm~2~154.1mm~2,and during the process of pushing,the height and area of L4-5 intervertebral foramen is slightly increased but not obvious.ConclusionsAs for the subjects with a height of about 170cm,this study can draw the following conclusions:1.For L4-5 disc with mild and moderate degeneration,the best pushing height of spinal manipulation bed is 8cm;for L4-5 intervertebral disc with severe degeneration,the pushing height is not clear;2.After pushing,the anterior stress of the fibrous ring of L4-5 disc with mild and moderate degeneration was significantly greater than that of the posterior;3.After the L4 and L5 spinous processes were pushed by the spinal manipulation bed,the size of L4-5 intervertebral foramen of L4-5 disc with mild and moderate degeneration were significantly larger than that before the pushing;the size of L4-5 intervertebral foramen of L4-5 disc with severe lumbar was not significantly changed. |
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