幼兒半椎體所致脊柱側(cè)凸后路矯形三維有限元分析
發(fā)布時間：2018-08-04 19:40
【摘要】：目的：先天性脊柱側(cè)凸是一種發(fā)病率高、嚴(yán)重影響患兒身心健康的疾病。尤其小年齡組脊柱側(cè)凸畸形患兒胸廓發(fā)育差、心肺功能不全，具有畸形復(fù)雜嚴(yán)重、手術(shù)并發(fā)癥發(fā)生率高、手術(shù)麻醉風(fēng)險大的特點，一直是脊柱側(cè)凸治療領(lǐng)域的難題。這種畸形需要早期手術(shù)矯治，但又需最大程度地減少對脊柱生長發(fā)育的影響。所以矯形方式和椎體融合節(jié)段的選擇是影響療效和預(yù)后的關(guān)鍵因素。目前后路半椎體切除椎弓根螺釘內(nèi)固定是主要的治療方式。但是，因患兒畸形復(fù)雜、個體之間畸形變化差異很大，在矯形過程中，固定節(jié)段的選擇主要根據(jù)醫(yī)生的臨床經(jīng)驗，其生物力學(xué)研究證據(jù)不足。所以易導(dǎo)致矯形欠佳、不滿意或術(shù)后出現(xiàn)脊柱失代償?shù)炔l(fā)癥�；诖�，本研究利用建立的幼兒半椎體所致脊柱側(cè)凸（Congenital scoliosis）三維有限元模型（finite element model，F(xiàn)EM）模擬后路半椎體切除、椎弓根螺釘固定矯形手術(shù)，并比較選擇不同固定節(jié)段的生物力學(xué)特點，從而為臨床提供理論依據(jù)。 方法： 1、獲取圖像：選取1名幼兒半椎體所致脊柱側(cè)凸患兒，男性，2歲9個月，胸12為半椎體，體重14kg，身高90cm。取平臥位，行西門子64排螺旋CT從第二頸椎上緣至骶骨掃描，層厚1.25mm，層間距0mm，，掃描范圍包括全部骨性結(jié)構(gòu)及椎間盤。獲得Dicom格式CT平掃圖像470張，實際建模采用中間有效部位148張。 2、建立三維幾何模型：將獲得的Dicom格式圖像，倒入逆向工程軟件Mimics14.0中，對原始圖像進行蒙版、分割、光滑等步驟生成胸椎、腰椎、椎間盤的初級三維模型。將模型的正側(cè)位視圖與臨床正側(cè)位X線片對比，并在模型上測量半椎體大小、體積、Cobb角等。 3、模擬后路矯形手術(shù)：對模型進行簡易處理后導(dǎo)入3-Matic5.1處理軟件中，進行模擬后路半椎體切除椎弓根螺釘內(nèi)固定手術(shù)。術(shù)中先行打入椎弓根螺釘，再行切除十二胸椎半椎體，安裝矯形棒，逐漸閉合T11和L1椎間隙，達(dá)到側(cè)凸畸形的矯正。與術(shù)后X線相比矯形效果滿意。 4、建立三維有限元模型：在3-Matic5.1中,將椎弓根螺釘和矯形棒以及椎骨、椎間盤裝配，裝配后整體進行網(wǎng)格劃分。劃分好后再次將先天性脊柱側(cè)凸模型導(dǎo)入Mimics14.0中，設(shè)置模型各個組件的彈性模量、柏松比等相關(guān)參數(shù)，得到先天性脊柱側(cè)凸三維有限元模型。 5、進行有限元分析：將已賦好材料屬性、劃分好網(wǎng)格的幼兒半椎體所致脊柱側(cè)凸模型導(dǎo)入有限元分析軟件ANSYS13.0中，對模型進行約束（于四組模型的底部進行約束，限定各個方向位移）、加載（最上面椎體上表面凹側(cè)施加垂直向下的壓力100N、200N、300N、400N、500、600N，凸側(cè)施加垂直向上的壓力100N、200N、300N、400N、500、600N）、求解，得到不同固定節(jié)段的等效應(yīng)力云圖和位移云圖，并比較不同固定節(jié)段的應(yīng)力和位移變化。 結(jié)果： 1建立了幼兒半椎體所致脊柱側(cè)凸三維有限元模型，包括胸椎、腰椎、椎間盤。共有105252個單元，185849個節(jié)點，其中胸椎模型2塊，單元31576個、節(jié)點56105個；腰椎模型2塊，單元37890個、節(jié)點67281個，椎間盤模型（髓核+纖維環(huán)）5塊，單元11577個、節(jié)點21163個。 2幼兒半椎體所致脊柱側(cè)凸有限元模型逼真的描繪了患兒脊柱的特點：幼兒脊柱椎體寬、略呈卵圓形；椎體高度明顯高于椎間盤厚度；椎體滋養(yǎng)孔多，孔徑較大；松質(zhì)骨與密質(zhì)骨相互包容，難以界定。模型于臨床大體像、X線片脊柱曲線吻合。胸12半椎體體積為3793mm3，最大長徑31.27mm，最大高度為15.13mm，術(shù)前Cobb角為40.2°。 3順利完成后路半椎體切除、椎弓根螺釘內(nèi)固定手術(shù)模擬。根據(jù)固定節(jié)段的不同，進行個體化分組，有T_(10)~L_1組(凹凸側(cè)各3枚螺釘)，T_(11)~L_1組（凹凸側(cè)各2枚螺釘）、T_(11)~L_2組（凹凸側(cè)各3枚螺釘）、T_(10)~L_2組（凹凸側(cè)各4枚螺釘），術(shù)后矯形效果均達(dá)到100%。 4軟件ANSYS13.0分析得出四種固定方案下模型的等效應(yīng)力（Equivalent Stress）分布圖、位移云圖和安全系數(shù)云圖。從圖中看出，隨著加載力值的逐漸增加(10~4N)，模型的位移云圖圖形、應(yīng)力云圖圖形基本無變化，而各云圖區(qū)域所代表的值，呈線性增長。四組固定方案的等效應(yīng)力云圖顯示，最大等效應(yīng)力主要集中在椎弓根螺釘釘頭與螺釘體、椎弓根螺釘與矯形桿、椎弓根螺釘與椎弓根交界處。四組固定方案的位移云圖顯示，其最大位移均在每一組的最上面椎體，并向下呈依次減小趨勢。 5在四組模型頂部凹側(cè)施加垂直向下的壓力300N，凸側(cè)施加垂直向上的壓力300N時，四組矯形方案T_(10)~L_1組、T_(11)~L_1組、T_(10)~L_2組、T_(11)~L_2組的最大等效應(yīng)力值分別為：52.552Mpa、59.422Mpa、55.215Mpa、59.624Mpa；四組脊柱模型凸側(cè)所受的等效應(yīng)力明顯大于凹側(cè)，約3-6倍；模型凸側(cè)的最上面和最下面椎體所受作用力較大，中間作用力相對較小。在四組矯形方案中，T_(11)~L_1組椎弓根螺釘所受作用力最大，向頭端或尾端各延長一個固定節(jié)段，椎弓根螺釘?shù)氖芰档停鏣_(10)~L_1組、T_(11)~L_2組。但向頭端或尾端再延長一個固定節(jié)段，如T_(10)~L_2組，對椎弓根螺釘?shù)氖芰o明顯影響。在四組矯形方案的安全系數(shù)云圖中，T_(11)~L_1組凸側(cè)矯形桿最小安全系數(shù)的圖像范圍是其他三組的4-8倍，而最小安全系數(shù)的區(qū)域越大越易造成疲勞破壞。總之，T_(10)~L_1、T_(11)~L_2兩組可作為較好的手術(shù)方案選擇。 結(jié)論： 1應(yīng)用先進的計算機輔助工程軟件Mimics14.0及ANSYS13.0，根據(jù)患兒CT圖像，可成功建立幼兒半椎體所致脊柱側(cè)凸三維有限元模型。應(yīng)用該模型可成功的模擬脊柱側(cè)凸的后路半椎體切除椎弓根螺釘內(nèi)固定三維矯形手術(shù)。 2幼兒半椎體所致脊柱側(cè)凸三維有限元模型可以在各種條件下進行應(yīng)力變化分析和模擬手術(shù)研究，為幼兒半椎體所致脊柱側(cè)凸疾病提供了良好的相關(guān)生物力學(xué)理論和臨床研究，為制定脊柱側(cè)凸患兒個性化手術(shù)方案提供了良好的生物力學(xué)研究基礎(chǔ)。
[Abstract]:Objective: congenital scoliosis is a disease with high incidence and serious physical and mental health, especially in children with scoliosis, especially in children with scoliosis deformity, poor cardiopulmonary function, complex and serious malformation, high incidence of surgical complications and high risk of anesthesia, which has always been a difficult problem in the field of scoliosis treatment. Malformation requires early surgical correction, but it needs to minimize the effect on the growth and development of the spine. Therefore, the choice of orthopedic and vertebral fusion segments is the key factor affecting the curative effect and prognosis. In the process of orthopedics, the selection of fixed segments is mainly based on the clinical experience of doctors, and the evidence of biomechanics is insufficient. Therefore, it is easy to lead to poor correction, dissatisfaction, or postoperative complications such as spinal decompensation. Based on this, this study uses the established Congenital scol of the established children's hemivertebra. Iosis) the three-dimensional finite element model (finite element model, FEM) is used to simulate posterior hemi vertebral resection, pedicle screw fixation, and compare the biomechanical characteristics of different fixed segments, so as to provide a theoretical basis for clinical practice.
Method:
1, obtain images: 1 children with hemivertebra caused scoliosis, male, 2 years and 9 months, 12 hemivertebra, body weight 14kg, height 90cm. horizontal position, SIEMENS 64 row spiral CT from second cervical spine to sacral scan, thickness 1.25mm, interlayer space 0mm, scan range including all bone structure and intervertebral disc. Obtain Dicom format CT flat. 470 images were swept, and 148 effective parts were used in actual modeling.
2, a three-dimensional geometric model is established: the obtained Dicom format image is inverted into the reverse engineering software Mimics14.0, and the primary three-dimensional model of the thoracic vertebra, the lumbar vertebra and the intervertebral disc is generated by the mask, segmentation, and smoothness of the original image. The model's positive side view is compared with the clinical positive lateral X ray, and the size of the hemi vertebral body is measured on the model. Product, Cobb angle, etc.
3, simulated posterior orthopedic surgery: after simple treatment of the model, the 3-Matic5.1 treatment software was introduced into the simulated posterior hemivertebra resection with pedicle screw fixation. The pedicle screws were inserted before the operation, the twelve thoracic vertebrae were resected, the orthopedics was installed, the T11 and L1 intervertebral space were gradually closed, and the correction of scoliosis deformity was achieved. The orthopedic effect was satisfactory compared with the postoperative X-ray.
4, establish a three-dimensional finite element model: in 3-Matic5.1, the pedicle screws and orthopedics, vertebrae, and intervertebral discs are assembled, and the whole mesh is meshed. Then the model of congenital scoliosis is introduced into Mimics14.0 again, and the modulus of elasticity of each component of the model is set, and the related parameters such as pines ratio are obtained, and the congenital scoliosis is obtained. A convex three-dimensional finite element model.
5, the finite element analysis is carried out: the model of the scoliosis caused by the children's semi vertebral body is introduced into the finite element analysis software ANSYS13.0. The model is constrained (the bottom of the four groups of models is constrained, the displacement is limited in all directions), and the vertical downward pressure is imposed on the upper surface of the upper body (10). 0N, 200N, 300N, 400N, 500600N, the vertical upward pressure 100N, 200N, 300N, 400N, 500600N) are applied. The equivalent stress and displacement clouds of different fixed segments are obtained, and the stress and displacement changes of different fixed segments are compared.
Result:
1 a three-dimensional finite element model of scoliosis caused by children's hemivertebra was established, including the thoracic vertebra, the lumbar vertebra, and the intervertebral disc. There were 105252 units and 185849 nodes, including the thoracic vertebra model 2, the unit 31576, the node 56105, the lumbar model 2, the unit 37890, the node 67281, the disc model (nucleus pulposus + ring) 5, the unit 11577, node 21163. One.
2 the finite element model of scoliosis caused by the hemivertebra of young children vividly depicts the characteristics of the children's spine: the children's spine is wide and slightly oval; the height of the vertebral body is obviously higher than the thickness of the intervertebral disc; the vertebral foramen is more and the pore size is larger; the cancellous bone and the dense bone are mutually inclusive and difficult to define. The model is in the clinical general image, the X-ray curve of the spine curve. The volume of the chest 12 semi vertebral body is 3793mm3, the maximum length 31.27mm, the maximum height is 15.13mm, the preoperative Cobb angle is 40.2 degrees.
3 successfully completed posterior hemi vertebral resection and pedicle screw internal fixation. According to the different segments, individual groups were divided into group T_ (10) ~L_1 (3 screws on the concave and convex sides), T_ (11) ~L_1 group (2 screws in concave and convex sides), T_ (11) ~L_2 group (3 screws in concave and convex sides), and T_ (10) ~L_2 group (4 screws in concave and convex sides), and the postoperative orthopedic effect was all Reach 100%.
4 software ANSYS13.0 analysis obtained the equivalent stress (Equivalent Stress) distribution diagram, displacement cloud map and safety coefficient cloud chart under four fixed schemes. As we can see, as the loading force increases gradually (10~4N), the displacement cloud graph of the model, the base of the stress cloud graph are not changed, and the values represented by each cloud map are linearly increasing. The equivalent stress cloud chart of the four groups of fixed schemes showed that the maximum equivalent stress was mainly concentrated on the Shiumi Ne screw head and screw body, the Shiumi Ne screw and the orthopedics, the Shiumi Ne screw and Shiumi Ne junction. The displacement cloud chart of the four groups of fixed schemes showed that the maximum displacement was in the top vertebral body of each group, and the downward trend decreased in turn. Potential.
5 at the top concave side of the four groups, the vertical downward pressure 300N was applied and the vertical upward pressure was applied on the convex side. The four groups of orthopedic schemes T_ (10) ~L_1, T_ (11) ~L_1, T_ (10) ~L_2, and T_ (11) ~L_2 group were the equivalent stress of the 52.552Mpa, 59.422Mpa, and four spinal models. In the four groups of orthopedic schemes, the force of the T_ (11) ~L_1 pedicle screws was the largest, the head or tail was extended a fixed segment, and the force of the pedicle screw was reduced, such as the T_ (10) ~L_1 group, T_ (11) ~ (11). L_2 group. But a further extension of a fixed segment to the head or tail, such as the T_ (10) ~L_2 group, has no obvious effect on the force of the pedicle screw. In the safety factor cloud of the four groups of orthopedics, the image range of the minimum safety factor of the T_ (11) ~L_1 group is 4-8 times that of the other three groups, and the greater the area of the minimum safety factor, the more vulnerable to fatigue. In conclusion, T_ (10) ~L_1, T_ (11) ~L_2 two can be used as a better surgical option.
Conclusion:
1 with advanced computer aided engineering software Mimics14.0 and ANSYS13.0, a three-dimensional finite element model of scoliosis caused by children's hemivertebra can be successfully established according to the CT images of children. The model can be successfully used to simulate the posterior hemivertebra resection of the vertebral pedicle screw for three-dimensional orthopedic surgery.
2 the three-dimensional finite element model of scoliosis caused by children's hemivertebra can be analyzed and simulated under various conditions. It provides a good biomechanical theory and clinical study for the scoliosis caused by hemivertebra in children, and provides good biology for the formulation of the individualized operation scheme for scoliosis patients. The foundation of mechanics research.
【學(xué)位授予單位】：河北醫(yī)科大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：R726.8
本文編號：2164943
[Abstract]:Objective: congenital scoliosis is a disease with high incidence and serious physical and mental health, especially in children with scoliosis, especially in children with scoliosis deformity, poor cardiopulmonary function, complex and serious malformation, high incidence of surgical complications and high risk of anesthesia, which has always been a difficult problem in the field of scoliosis treatment. Malformation requires early surgical correction, but it needs to minimize the effect on the growth and development of the spine. Therefore, the choice of orthopedic and vertebral fusion segments is the key factor affecting the curative effect and prognosis. In the process of orthopedics, the selection of fixed segments is mainly based on the clinical experience of doctors, and the evidence of biomechanics is insufficient. Therefore, it is easy to lead to poor correction, dissatisfaction, or postoperative complications such as spinal decompensation. Based on this, this study uses the established Congenital scol of the established children's hemivertebra. Iosis) the three-dimensional finite element model (finite element model, FEM) is used to simulate posterior hemi vertebral resection, pedicle screw fixation, and compare the biomechanical characteristics of different fixed segments, so as to provide a theoretical basis for clinical practice.
Method:
1, obtain images: 1 children with hemivertebra caused scoliosis, male, 2 years and 9 months, 12 hemivertebra, body weight 14kg, height 90cm. horizontal position, SIEMENS 64 row spiral CT from second cervical spine to sacral scan, thickness 1.25mm, interlayer space 0mm, scan range including all bone structure and intervertebral disc. Obtain Dicom format CT flat. 470 images were swept, and 148 effective parts were used in actual modeling.
2, a three-dimensional geometric model is established: the obtained Dicom format image is inverted into the reverse engineering software Mimics14.0, and the primary three-dimensional model of the thoracic vertebra, the lumbar vertebra and the intervertebral disc is generated by the mask, segmentation, and smoothness of the original image. The model's positive side view is compared with the clinical positive lateral X ray, and the size of the hemi vertebral body is measured on the model. Product, Cobb angle, etc.
3, simulated posterior orthopedic surgery: after simple treatment of the model, the 3-Matic5.1 treatment software was introduced into the simulated posterior hemivertebra resection with pedicle screw fixation. The pedicle screws were inserted before the operation, the twelve thoracic vertebrae were resected, the orthopedics was installed, the T11 and L1 intervertebral space were gradually closed, and the correction of scoliosis deformity was achieved. The orthopedic effect was satisfactory compared with the postoperative X-ray.
4, establish a three-dimensional finite element model: in 3-Matic5.1, the pedicle screws and orthopedics, vertebrae, and intervertebral discs are assembled, and the whole mesh is meshed. Then the model of congenital scoliosis is introduced into Mimics14.0 again, and the modulus of elasticity of each component of the model is set, and the related parameters such as pines ratio are obtained, and the congenital scoliosis is obtained. A convex three-dimensional finite element model.
5, the finite element analysis is carried out: the model of the scoliosis caused by the children's semi vertebral body is introduced into the finite element analysis software ANSYS13.0. The model is constrained (the bottom of the four groups of models is constrained, the displacement is limited in all directions), and the vertical downward pressure is imposed on the upper surface of the upper body (10). 0N, 200N, 300N, 400N, 500600N, the vertical upward pressure 100N, 200N, 300N, 400N, 500600N) are applied. The equivalent stress and displacement clouds of different fixed segments are obtained, and the stress and displacement changes of different fixed segments are compared.
Result:
1 a three-dimensional finite element model of scoliosis caused by children's hemivertebra was established, including the thoracic vertebra, the lumbar vertebra, and the intervertebral disc. There were 105252 units and 185849 nodes, including the thoracic vertebra model 2, the unit 31576, the node 56105, the lumbar model 2, the unit 37890, the node 67281, the disc model (nucleus pulposus + ring) 5, the unit 11577, node 21163. One.
2 the finite element model of scoliosis caused by the hemivertebra of young children vividly depicts the characteristics of the children's spine: the children's spine is wide and slightly oval; the height of the vertebral body is obviously higher than the thickness of the intervertebral disc; the vertebral foramen is more and the pore size is larger; the cancellous bone and the dense bone are mutually inclusive and difficult to define. The model is in the clinical general image, the X-ray curve of the spine curve. The volume of the chest 12 semi vertebral body is 3793mm3, the maximum length 31.27mm, the maximum height is 15.13mm, the preoperative Cobb angle is 40.2 degrees.
3 successfully completed posterior hemi vertebral resection and pedicle screw internal fixation. According to the different segments, individual groups were divided into group T_ (10) ~L_1 (3 screws on the concave and convex sides), T_ (11) ~L_1 group (2 screws in concave and convex sides), T_ (11) ~L_2 group (3 screws in concave and convex sides), and T_ (10) ~L_2 group (4 screws in concave and convex sides), and the postoperative orthopedic effect was all Reach 100%.
4 software ANSYS13.0 analysis obtained the equivalent stress (Equivalent Stress) distribution diagram, displacement cloud map and safety coefficient cloud chart under four fixed schemes. As we can see, as the loading force increases gradually (10~4N), the displacement cloud graph of the model, the base of the stress cloud graph are not changed, and the values represented by each cloud map are linearly increasing. The equivalent stress cloud chart of the four groups of fixed schemes showed that the maximum equivalent stress was mainly concentrated on the Shiumi Ne screw head and screw body, the Shiumi Ne screw and the orthopedics, the Shiumi Ne screw and Shiumi Ne junction. The displacement cloud chart of the four groups of fixed schemes showed that the maximum displacement was in the top vertebral body of each group, and the downward trend decreased in turn. Potential.
5 at the top concave side of the four groups, the vertical downward pressure 300N was applied and the vertical upward pressure was applied on the convex side. The four groups of orthopedic schemes T_ (10) ~L_1, T_ (11) ~L_1, T_ (10) ~L_2, and T_ (11) ~L_2 group were the equivalent stress of the 52.552Mpa, 59.422Mpa, and four spinal models. In the four groups of orthopedic schemes, the force of the T_ (11) ~L_1 pedicle screws was the largest, the head or tail was extended a fixed segment, and the force of the pedicle screw was reduced, such as the T_ (10) ~L_1 group, T_ (11) ~ (11). L_2 group. But a further extension of a fixed segment to the head or tail, such as the T_ (10) ~L_2 group, has no obvious effect on the force of the pedicle screw. In the safety factor cloud of the four groups of orthopedics, the image range of the minimum safety factor of the T_ (11) ~L_1 group is 4-8 times that of the other three groups, and the greater the area of the minimum safety factor, the more vulnerable to fatigue. In conclusion, T_ (10) ~L_1, T_ (11) ~L_2 two can be used as a better surgical option.
Conclusion:
1 with advanced computer aided engineering software Mimics14.0 and ANSYS13.0, a three-dimensional finite element model of scoliosis caused by children's hemivertebra can be successfully established according to the CT images of children. The model can be successfully used to simulate the posterior hemivertebra resection of the vertebral pedicle screw for three-dimensional orthopedic surgery.
2 the three-dimensional finite element model of scoliosis caused by children's hemivertebra can be analyzed and simulated under various conditions. It provides a good biomechanical theory and clinical study for the scoliosis caused by hemivertebra in children, and provides good biology for the formulation of the individualized operation scheme for scoliosis patients. The foundation of mechanics research.
【學(xué)位授予單位】：河北醫(yī)科大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：R726.8
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