The Finite-element Analysis Of The Court Bonesetting Wan Yao Ting Li Manipulation Treating Lumbosacral Joint Disorder

BackgroundLumbago is one of the most common symptoms of clinical orthopedics,and the lumbar facet joint disease is a common disease in the waist,which is one of the causes of low back pain.Lumbar facet joint disorder means the dislocation of the lumbar articular process joints,which leads to the pain,dysfunction and so on.It mainly results from the waist's incorrect posture or sudden flash,torsion injuries,which performs as low back pain?hip pain or lumbarsacral pain in clinical,and it needs to distinguish from the nerve root's low back pain and the strain of lumbar muscles.The disease occurs mostly in L4-L5 and L5-S1,and occurs among 20-40 year-old adults largely.It can be related to muscle,ligaments,fascia,intervertebral joints,lumbosacral joint or sacroiliac joint,which belongs to the category of "lower back pain" and "cramp" of Traditional Chinese Medicine.Lumbosacral joint belongs to lumbar facet joint,and the waist activity is limited by the severity of the disease,and the influence on the quality of life is significant.Methods for the treatment of the disease vary,and different methods have different clinical effects.The Court Bonesetting Wan Yao Ting Li Manipulation which created by professor Shu-chun Sun is one of the unique and effective way of treating lumbosacral joint disorder,and application in clinical experience obtained satisfactory therapeutic effect.However,previous research of Wan Yao Ting Li Manipulation only confines to the lumbosacral joint's biomechanics and clinical research,and it still needs to furtherly explore the mechanism of the manipulation to facilitate the clinical application and popularization of the technique.In recent years,the finite element method has been applied to the biomechanical study of the manipulation more and more,and it has opened up a new way to study the mechanism of manipulation.We haven't found any research on the combination of finite element analysis technique and Wan Yao Ting Li Manipulation yet from the published literatures.It is helpful to furtherly explore the mechanism of Wan Yao Ting Li Manipulation by simulating the stress and displacement distribution of the manipulation treating lumbosacral joint disorder segment and normal segment via the finite element analysis technique.Objective1 To set up two three-dimensional finite element models of lumbosacral joint and verify their reliability and validity and to explore the possible intrinsic factors of lumbosacral joint disorder.2.To analyse the lumbosacral joint's stress and displacement distribution of the normal and abnormal model under natural load of neutral position,and preliminarily explore the biomechanical changes of lumbosacral segment after lumbosacral joint disorder.3.To analyze the lumbosacral joint's stress and displacement distribution of the normal and abnormal model during the simulation of Wan Yao Ting Li Manipulation,and to explore the mechanism of this manipulation treating lumbosacral joint disorder disease.MethodsCollect the CT images of lumbosacral joint segments from a normal volunteer and a patient with lumbosacral joint disorder,and use Mimics 10.01,Solidworks 2016,Hypermesh 12.0 software for image positioning,smoothing,reverse processing,meshing and other steps to establish normal lumbosacral segment and lumbosacral joint disorder segment of the three-dimensional finite element model.After verifying the validity of the two models,the two models are loaded with the following three conditions respectively:(1)Constraint S1 vertebral and the place below S1 comprehensively,which limits the translation and rotation,a total of six degrees of freedom.Then load an axial compression load of two thirds of the body's weight on the surface of L5 vertebral in two models,which means that the normal and abnormal model are loaded 431.20N and 463.87N respectively.Then use Abaqus 6.13 software to analyse the two models' stress and displacement distribution under natural load of neutral position,which is operating condition 1;(2)According to the principle of Wan Yao Ting Li Manipulation and combining with the results of previous research findings,constraint S1 vertebral and the place below S1 comprehensively,and the model is put forward above 34° on L5 spinous process with a load of 186.1 ON,and then analyse the two models' stress and displacement distribution under Wan Yao Ting Li Manipulation,which is operating condition 2;(3)Constraint L5 vertebral comprehensively,and apply 2215.66N on sacral auricular surface verticaly,and analyse the two models' stress and displacement distribution,which is operating condition 3.Results1 Set up two three-dimensional finite element models of lumbosacral joint,and it shows that both of them are precise and effective after verifying their reliability and validity.2 The distribution of stress and displacement of the lumbosacral joints under natural load of neutral position2.1 stress distribution2.1.1 L5 vertebral and posterior structureThe stress distribution of normal model's L5 vertebral segment is mainly concentrated on the ventral side of the vertebral pedicle on both sides,on both sides of the lower articular process and the leading edge of the lower endplate.Compared with the normal lumbosacral model,lumbosacral joint disorder model's L5 vertebral stress is concentrated in the center of the lower endplate,and the stress decreases from the center to the periphery.2.1.2 intervertebral discThe stress distributes evenly on both sides and on the front part of the fiber ring edge,and the stress is not obvious on the trailing edge.By contrast,the lumbosacral joint disorder segment shows obvious stress concentration,mainly in the middle of the intervertebral disc,and the stress concentration of the rest part is not obvious.2.1.3 S1 vertebra and posterior structureUnder natural load of neutral position,the stress of normal lumbosacral joint S1 is relatively and evenly distributes in fanterior edge and vertebral pedicle,and lumbosacral joint disorder model's stress concentration distributes in fanterior edge and trailing edge.2.2 displacement distribution2.2.1 L5 vertebral and posterior structureThe displacement distribution of normal model L5 vertebral body changes symmetrically and evenly,and the maximal displacement distribution is in the right-front part of the vertebral body.It deceases evenly along the front—trailing edge—vertebral pedicle—articular process—vertebral plate—spinous process,and from the top upper end plate to the lower end plate.The displacement distribution of the lumbosacral joint disorder model is obviously asymmetrical,and the maximum displacement is distributed on the left side of the transverse process,the upper and lower articular process and the left side of the spinous process,which gradually reduces from left to right.2.2.2 intervertebral discThe displacement distribution of intervertebral disc in normal model is consistent,and it mostly distributed in the right-front upper part of the disc,descending from the right-front to the left-posterior,and the minimum displacement is located in the left rear.The displacement distribution of the lumbosacral joint disorder model is not consistent,which mainly concentrates in the front part.and the displacement distribution of the posterior margin of the intervertebral disc is basically consistent,which counts the same basically.2.3 ligament stressThe tension of the ligament of the normal model and the abnormal model is basically consistent,the anterior longitudinal ligament,the posterior longitudinal ligament is relaxed,the ligamentum flavum,the interspinous ligament and the supraspinous ligament are tense,and the tension increases.3 The stress distribution and displacement of each structure of the lumbosacral joint under Wan Yao Ting Li Manipulation3.1 operating condition 23.1.1 stress distribution3.1.1.1 L5 vertebral and posterior structureThe stress distribution of normal L5 vertebral segment is mainly focused on the posterior margin of the upper endplate and the right-front of the lower endplate.In the posterior structure of the vertebral body,the stress symmetrically concentrates in the bilateral vertebral pedicle and ventral part of vertebral isthmus.The stress concentration of the abnormal L5 vertebral body is concentrated in the leading edge and posterior part of upper endplate and the central circular region of the lower endplate,The stress distribution of the other part is not obvious.3.1.1.2 intervertebral discNormal segmental's L5-S1 intervertebral disc stress concentrates in the region of the left and right sides of the fiber ring,but the intervertebral disc stress of disorder model is more focused,and it concentrates in a small circular part of nucleus pulposus,and the stress of the other part is not obvious.3.1.1.3 S1 vertebral body and posterior structureThe stress of the sacral vertebral in the normal segment is concentrated in the vertebral pedicle and the upper articular process.Compared with the normal model,the stress of the disorder model is distributed in the anterior and posterior margins of the vertebral body.3.1.2 The displacement distribution3.1.2.1 L5 vertebral body and posterior structureThe maximum displacement of normal model L5 segmental is located in the upper articular process and the right margin of the right transverse process.The displacement decreases from right to left equally,and its minimum displacement is in the left margin of the left side of the transverse process.In the disorder model,the displacement is most distributed on the left side of the left transverse process,lower articular process and the left side of spinous process,and gradually reduced from the right-posterior to the left-anterior.3.1.2.2 intervertebral discThe displacement distribution of the L5-S1 intervertebral disc is consistent with that of the L5 vertebral body and the posterior structure.In the normal model,the displacement gradually decreases from right to left,and the minimum displacement is located in the triangular region of the left fiber ring.The abnormal model of intervertebral disc displacement is concentrated in the peripheral of the fiber ring in the left side of the intervertebral disc.3.1.2.3 intervertebral foramen and articular process jointAs we can see from the two video animations during the simulation under operating condition 2,the intervertebral foramen and articular process joint of both models moves obviously.And the L5 vertebral body moves forward,making the area of intervertebral foramen bigger.The lower articular process of L5 moves forward,which reduces the interface of articular process joint.After the loading force is removed,it restores to its original position.3.1.3 ligament stressThe tension of the ligament of the normal model and the abnormal model is basically consistent.The anterior longitudinal ligament is slack,while the posterior longitudinal ligament,the ligamentum flavum,the interspinous ligaments and the supraspinous ligament are tense,and the tension increases.3.2 operating condition 33.2.1 stress distribution3.2.1.1 L5 vertebral body and posterior structureIn the simulation condition of the ground reaction force of normal L5 vertebral segment,the stress distribution is mainly concentrated on the anterior and posterior margin of vertebral endplate.In the back part of the structure,stress concentration is in the lumbar isthmus,the ventral part of vertebral pedicle and vertebral plate.By contrast,the abnormal model is basically similar to that of normal,focusing on the ventral part vertebral pedicle,isthmus and dorsal side of vertebral plate.3.2.1.2 intervertebral discThe stress of the normal L5-S1 intervertebral disc model is concentrated in the small elliptical region of the right margin of the fiber ring.And the stress distribution is scattered in the small circular region in the disorder model.3.2.1.3 S1 vertebral body and posterior structureIn the normal model,the stress of the sacrum is concentrated on the left margin of the vertebral body and the sacral crest,while the stress is mainly distributed in the posterior margin of the sacral vertebral body and the sacral crest in the abnormal model.3.2.2 the displacement distribution3.2.2.1 L5 vertebral body and posterior structureIn the normal model L5 vertebral body and posterior structural's displacement is maximally concentrated on the tip of spinous process,which is decreasing from the back to forward,and the minimum displacement appears in the upper endplate.In the disorder model,it is almost the same with the normal model,and the maximum displacement is concentrated on the tip of spinous process.Because the L5 vertebral body is fixed,it's displacement is very small.3.2.2.2 intervertebral discThe maximum intervertebral disc displacement in the normal model is concentrated in the leading edge region of the fiber ring,which gradually reduces from anterior to posterior.In the disorder model,the maximum displacement occurs in the lower part of the fiber ring of the anterior disc.3.2.2.3 intervertebral foramen and articular process jointAs we can see from the two video animations during the simulation under operating condition 3,the articular process joint of both models moves obviously.The upper articular process moves toward underneath and the distance of articular process joint increases and the change of intervertebral foramen area is relatively small.After the loading force is removed,it restores to its original position.3.2.2.4 S1 vertebra and posterior structure.In both models,the displacement of the sacrum is more concentrated and obvious than the L5 vertebra and intervertebral disc.The maximal displacement of the sacrum in the normal model occurres in the posterior margin of the sacral vertebral body and the sacral median ridge.In the disorder model,it is almost the same with the normal.3.2.3 ligament stressThe tension of the ligament of the normal model and the abnormal model is basically consistent.The stress of anterior longitudinal ligament changes little,while the posterior longitudinal ligament,the ligamentum flavum,the interspinous ligament and the supraspinous ligament are flabby,and the tension decreases.Conclusion1 Compared with normal lumbosacral joint segmental model,the degeneration of intervertebral disc in the model of lumbosacral joint disorder causes changing structure of lumbosacral joint stress,which may be the intrinsic factor of lumbosacral joint disorder.2 During the process of Wan Yao Ting Li Manipulation,the stress is concentrated in the vertebral pedicle and lumbar isthmus,indicating that twe should paid attention to the technique of manipulation,so as to avoid blind exertion,and not to cause fracture.3 During the process of Wan Yao Ting Li Manipulation,the upper and lower articular processes develops relative displacement,which may be the main mechanism for the reposition of the manipulation.