| Objective To bulid the three-dimensional finite elementbiomechanical model and Verify the reliability of the model;Usingthe established lumbar vertebra pelvic-proximal femur model，simulation Lumbar fixed-point Sitting-rotatory manipulation,Explore the mechanism of Lumbar fixed-point Sitting-rotatorymanipulation, and evaluate the safety of Lumbar fixed-pointSitting-rotatory manipulation.Method Using64slice Spiral computed tomography (CT), scanned thevolunteer from the inferior margin of12th thoracic vertebra to thesuperior margin of bilateral proximal femur. obtained879CTpictures about original image of the volunteer,and stored them withDICOM format. Imported those CT pictures which with DICOM formatinto Mimics10.01, masked and edited them. Use the function ofthree-dimensional reconstruction,built the model of lumbarvertebra-pelvic-proximal femur; Imported the model into geomagic12and further modified it (function of reducing noise, relaxating,removing nails, fastly smoothing, sandpaper, filling holes,automatic repairing) in order to make the meshing easily. Confirmed there were not self-intersecting triangles in the model, thenimported the model. Imported the geometric model into hypermesh10modified by geomagic12, divied the model with tetrahedron gridand added the inter-vertebral disc (distinguish the annulusfibrosus and nucleus pulposus) and relevant ligament. refer torelevant literature, set the material properties of each part ofthe model. set the surface of bilateral proximal femur’s bottomas boundary, simulation lumbar oblique-pulling manipulation,Lumbar stretch-pulling manipulation and lumbar Sitting rotatory manipulation. Designed three conditions. condition①: noload, dextrorotation15°; condition②: anteflexion15°,Vertical load300N, dextrorotation15°;condition③: anteflexion15°, tract300N, dextrorotation15°. Refer to the data obtainedby previous biological mechanics experiment and the finite elementanalysis loaded the model,in order to Verify the validity of themodel. According to the principle of the Lumbar fixed-pointSitting-rotatory manipul-ation, divided it and loded the modelwith four congitions by changing the angle of lumbar anteflexionand lateral flexion. Condition④: X-axis anteflexion15°, Y-axis lateral flexion15°, Z-axis dextrorotation15°, load300NVertically on L1vertebra body, load15Nm running torque towardsthe right on L1vertebra body, load15Nm running torque at L4spinous process towards left anterior30°; Condition⑤: X-axisanteflexion15°, Y-axis lateral flexion9°, Z-axisdextrorotation15°, load300N Vertically on L1vertebra body, load15Nm running torque towards the right on L1vertebra body, load15Nm running torque at L4spinous process towards left anterior30°; Condition⑥: X-axis anteflexion20°, Y-axis lateral flexion12°, Z-axis dextrorotation15°, load300N Verticallyon L1vertebra body, load15Nm running torque towards the righton L1vertebra body, load15Nm running torque at L4spinous processtowards left anterior30°; Condition⑦: X-axis anteflexion15°, Y-axis lateral flexion20°, Z-axis dextrorotation15°,load300N Vertically on L1vertebra body, load15Nm running torquetowards the right on L1vertebra body, load15Nm running torqueat L4spinous process towards left anterior30°.Imported therelated data into three-dimensional finite element model andoperated, to obtain the displacement and stress-distribution ineach part of the model effected by Lumbar fixed-point Sitting rotatory manipulation.Result①Obtained the-dimensionalfinite element model including: bone of lumbar vertebra-pelvic-proximal femur (distinguish between Cancellous bone and Compactbone), lumbar inter-vertebral disc (distinguish between nucleuspulposus and annulus fibrosus), and Anterior longitudinalligament，Posterior longitudinal ligament，Liga-ment flava，Supraspinal ligament，Interspinal ligaments，Sacrospinou ligament,Sacrotuberous ligament, Iliolumbar ligament, Inguinal ligament.with which290771node,1321886tetrahedralsolid element and296spring element.②In the condition of no load, dextrorotation15°, compare the displacement and stress-distribution in the lumbarvertebra-pelvic-proximal femur, lumbar inter-vertebral discand each ligament with tracted and Vertical loaded, The value ofeach index is generally smaller obviously.③In the condition ofdextrorotation15°, tracted and Vertical loaded, the value of thedisplacement and stress-distribution in the lumbar vertebra-pelvic-proximal femur, lumbar inter-vertebral disc and each ligament decreasing from superior to inferior; the distribution ofstress concentrated upon vertebral pedicle, umbar facet joint,sacroiliac joint and collum femoris, right more obviously.④Inthe condition of anteflexion15°, change with the angle of lateralflexion（9°-15°-20°）, the value of displacement in the same planeof the lumbar vertebra-pelvic-proximal femur, lumbar inter-vertebral disc and each ligament increasing. The largest valueappear on the condition of anteflexion20°, lateral flexion12°.⑤In the condition of anteflexion15°, change with the angleof lateral flexion（9°-15°-20°）, the value of stress in the sameplane of the lumbar vertebra-pelvic-proximal femur, lumbar inter-vertebral disc and each ligament increasing. The largest valueof lumbar vertebra-pelvic-proximal femur appear on the conditionof anteflexion20°, lateral flexion12°, The largest value oflumbar inter-vertebral disc appear on the condition of anteflexion15°, lateral flexion20°.⑥In the condition of simulatingLumbar fixed-point Sitting-rotatory manipulation, the trendencyof displacement in the lumbar vertebra-pelvic-proximal femur,lumbar inter-vertebral disc and each ligament descreasing fromsuperior to inferior, and from the right antero-superior to leftpostero-inferior，and descreasing from the right antero-superiorto left postero-inferior in the same plane in the lumbar vertebra-pelvic-proximal femur, lumbar inter-vertebral disc and eachligament follow this law also. For the displacement of vertebra-pelvic-proximal femur, there almost little displacement below theleft articulatio coxa. But there was obvious displacement in leftIliolumbar ligament， right Sacrospinou ligament and rightSacrotuberous ligament.⑦In the condition of simulating Lumbar fixed-point Sitting-rotatory manipulation, the trendency ofstress in the lumbar inter-vertebral disc and each ligamentincreasing from superior to inferior, and from the leftposterosuperior to right anteroinferior.⑧In the condition ofsimulating Lumbar fixed-point Sitting-rotatory manipulation,the trendency of stress in the lumbar vertebra-pelvic-proximalfemur was not occurred any regular distribution. The distributionof stress concentrated upon vertebral pedicle, umbar facet joint,sacroiliac joint and collum femoris, right more obviously.⑨Asa whole，nucleus pulposus and annulus fibrosus have not synchronousdisplacement with adjacentlumbar.there was a relative displacementbetween adjacent lumbar and lumbar inter-vertebral disc,about1-3mm. at the same time, there was not synchronous stress betweennucleus pulposus and annulus fibrosus. What is more, differentsignificantly.Conclusion1. Built the three-dimensional finite element model oflumbar vertebra-pelvic-proximal femur successfully，it can beused to simulate Lumbar fixed-point Sitting-rotatorymanipulation and make the finite element analysis.2. During theoperation of Lumbar fixed-point Sitting-rotatoryr manipulation,both anteflexion and lateral flexion was the main factor whicheffects the displacement and stress in the lumbar vertebra-pelvic-proximal femur (distinguish between Cancellous bone and Compactbone), lumbar inter-vertebral disc (distinguish between nucleuspulposus and annulus fibrosus), and each ligament. relativelyspeaking， anteflexion put more important influence on thebone(distinguish between Cancellous bone and Compact bone). andlateral flexion put more important influence on the lumbar inter -vertebral disc (distinguish between nucleus pulposus and annulusfibrosus).3. Those can occurre when the lumbar Sitting-rotatorymanipulation was operated, that disordered umbar facet joint wasadjusted, and adhered umbar facet joint was released. the pain inwaist and lower extremities caused by disoredered umbar facet jointand incarcerated synovial membrane was relieved accordingly.4.During the operation of lumbar Sitting-rotatory manipulation, wemust pay attention to the direction and the force ofmanipulation,lest aggravating clinical symptoms or giving rise tocomplications. |
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