【作者】 吴寅良；

【导师】 杨惠林；

【作者基本信息】 苏州大学 ， 骨科学， 2007， 硕士

【摘要】 骶骨肿瘤手术通常需要选择性进行骶骨切除，由于骶骨参与组成的骶髂关节是中轴骨和下肢骨之间的唯一力学连接结构，骶骨切除必然会对局部的生物力学结构产生影响，而且对整个骨盆结构的力学传导产生影响。然而，目前国内外鲜见关于选择性切除骶骨后骨盆力学特性的文献报道。基于此，本实验针对选择性切除骶骨进行系列研究，通过标本模型和有限元模型，系统地测试骨盆的力学特性的变化，判断对其稳定性和承重能力的影响；并针对骶骨全切后的情况设计一种新型的人工骶骨假体，以期在结构上恢复中轴骨和骨盆连接的同时，在生物力学上恢复必要的承重和应力传导作用。此课题分以下三个部分。第一部分骶骨切除的骨盆生物力学分析目的：研究正常骶骨的力学特性和选择性切除骶骨后对骨盆力学结构产生的生物力学效应，探讨骶骨部分切除后重建的必要性。方法：采用6具成人防腐骨盆标本，于检验器具里固定双侧坐骨结节模拟坐姿，通过WE-5电子万能试验机垂直方向实行分级加载0、200、400、600、800、1000N，分别测量并记录骨盆完整时、经S3、S2、S1神经孔上下缘横行切除骶骨时、切除一侧骶髂关节时骨盆的主要应力传导路径和应力分布、应力应变关系、位移趋势以及刚度变化，测量并记录经S1神经孔上缘切除后残余骶骨结构的极限载荷。结果：随着骶骨切除平面越向头侧，经S3孔上缘、经S2孔下缘、经S2孔上缘切除时骶髂关节骶骨侧应力值增加很少。经S1孔下缘切除时骶髂关节应力明显增加为37.10Mpa，经S1孔上缘时应力值急剧增加达48.20Mpa，对整个骨盆轴向刚度影响50～60％，弯曲刚度和位移也明显增大。切除一侧骶髂关节时，未切除侧骶髂关节处应力增加为59.60Mpa。残余的髂骨坍塌并靠向残存的骶骨，重心内移，骨盆环重构。经S1孔上缘横行切除时其骨盆的破坏载荷为P_max=2042.50±46.25N。结论：骶骨的主要应力传导结构位于S1以上。当切除达S1孔平面以上时，随着骶髂关节面积急剧减少，前方骨皮质及其周围骨结构被严重破坏，应力传导方向偏离正常，局部应力产生突变，严重损害了骨盆稳定性，在日常的活动如坐立、行走时有产生骨折的危险。第二部分骶骨切除的三维有限元模型分析目的：研究正常骨盆和选择性切除骶骨后骨盆力学结构产生的生物力学效应，探讨骶骨切除后重建的必要性。方法：通过一成年男子的骨盆薄层CT扫描数据，建立正常骨盆和不同方式范围切除部分骶骨后的骨盆三维有限元模型，模拟站立位和坐位时于骶骨底加载正常生理载荷及极限载荷，计算并记录骶骨完整时、经S3、S2、S1孔上下缘平面切除后、累及一侧S1和骶髂关节的骶骨肿瘤刮除术后、切除一侧部分骶髂关节直至S1孔上缘水平以上和切除一侧骶髂关节等10种骨盆模型的主要应力分布、应力传导方向和位移。结果：骶骨应力主要分布在S1以上骶段的前部。随着切除平面的提高，经S3孔上缘、经S2孔下缘、经S2孔上缘切除时骶髂关节骶骨侧应力值增加很少。经S1孔下缘切除时应力值明显增加为2.1倍，经S1孔上缘时应力值急剧增加达4.3倍，而骶髂关节髂骨侧只在经S1孔下、上缘切除时分别增加67.7％和87.5％，对整个骨盆轴向刚度影响50～60％，做更多切除时，骶髂关节骶骨侧应力增加更多，而髂骨侧突变，骤减54.3％。逐步增加载荷，上述部位应力值也明显增加，而且位移增大。切除一侧骶髂关节时，另侧骶髂关节骶骨侧应力增加3.98倍，髂骨侧则增高达4倍，且其最大应力值转移到坐骨切迹部位，远超骶骨侧。残余的髂骨坍塌并靠向残存的骶骨，重心内移。结论：骶骨的主要应力传导结构位于S1以上。当切除达S1孔平面以上时，骶髂关节大部分被切除，骶骨前方骨皮质及其周围骨结构严重破坏，应力传导方向偏离正常，局部应力值急剧增高，位移增大，严重损害了骨盆的稳定性，在正常的活动中有产生骨折的危险。对骶骨切除后进行重建应尽可能恢复这种生理性应力传导结构。对于骶骨切除对骨盆结构的力学影响，标本模型和有限元模型力学分析显示了相同的变化趋势第三部分新型人工骶骨假体的设计目的：设计一种应用于骶骨全切术后能够稳定骨盆环，承担生理载荷，有效恢复正常应力传导结构的新型人工骶骨假体。方法：采集病人的骨盆CT资料，通过有限元三维建模分析，确定骶骨主要应力传导结构。运用三维建模技术设计个体化假体，形状拟合S1前侧主要应力传导的骨结构。组合安装骨盆和假体进行有限元应力分析，判断假体承担载荷、传导应力和维持骨盆稳定的有效性。采集19例正常骨盆CT资料作三维重建，模拟骶骨切除后安装骶骨假体，测量相关尺寸。结果：由于骶骨切除的范围和残余的髂骨翼的大小不同，假体的规格在术前确定切除范围后决定。假体结构部分可调。有限元分析结果显示，整个骶骨假体内固定系统重建了骨盆环，并形成了稳定的承重结构，可以将腰椎下传的应力通过假体传导至双侧髋关节或坐骨结节。应力传导的三维空间路径很好地拟合了正常骨盆的应力传导路径，没有出现过度应力集中。结论：设计的新型个体化人工骶骨假体模型既能够很好地承重，又模拟了正常的应力传导路径，并稳定了骨盆环，符合生理需要。但是，能否真正应用于临床还有待进一步研究。综上所述，通过选择性骶骨切除的骨盆生物力学模型和有限元模型的实验研究，发现骶骨主要的应力传导结构位于S1以上，切除骶骨达S1孔以上则产生局部应力突变，严重破坏骨盆的稳定性，在正常的活动中有产生骨折的危险。对骶骨切除后进行重建应尽可能恢复这种生理性应力传导结构，实验设计的新型人工骶骨假体经过有限元模型测试，认为既能够很好地承重，又模拟了正常的应力传导路径，并稳定了骨盆环，符合生理需要。更多还原

【Abstract】 With the development of surgery, a lot of patients have been cured by selectivesacrectomy. Sacrum is the unique structure which connect lumbar and pelvis, selectivesacrectomy will harm this structure and even damage the whole continuity. We conducted aseries of research, to investigate the biomechanical properties of normal sacrum andmodels after selective sacrectomy in both experimental (cadaveric) and numerical (FEA)approaches, to judge the necessity of reconstruction after sacrectomy, to design a newsacrum prosthesis for reconstruction after total sacrectomy.Part 1OBJECTIVE: To investigate the biomechanical properties of normal sacrum anddifferent levels of partial sacrectomy.METHODS: Six human cadaveric pelves wereplaced on a testing apparatus simulating the posture of sitting. When the superior surfacewas loaded by 0, 200, 400, 600, 800, 1000N in turn after selective resection, which wereabove or below the level of S3, S2, S1 foramina, the main stress value and distribution,displacement and stiffness changes of the sacrum were detected and analyzed. The ultimateload after resection cephalad to the S1 foramina was recorded. RESULTS: The max strainchanged between 552-686μεat sacrum. Stress was mainly distributed above S1.Sacroiliac joint stress and strain did not increase significantly when resection involved theS2 and S3 foramina. As the load increased, the stress and displacement of the pelvisincreased too. When cephalad to the S1 foramina, the ultimate load measured was2042.50±46.25N. After excision of the sacral portion of the sacroiliac joint, the intrajointstress increased on both the sacral and the iliac side. The residual ilium collapsed and moved medially towards the remaining sacrum. CONCLUSIONS: The component aboveS1 is the most important part of stress transduction within the sacroiliac joint. Afterexcision above the foramina of S1, the physiological load beating ability of sacrum washarmed critically, which may result in fracture with normal activity.Part 2OBJECTIVE: To investigate the biomechanical properties of normal sacrum anddifferent levels of partial sacrectomy.METHODS: By using finite element models (FEM)based on CT image data of human pelves, the pelvic mechanical behavior was calculatedsimulating standing on two legs or sitting. The main stress value and stress distributionwere analyzed when the superior surface of the sacrum was loaded. Selective sacrectomywere conducted above or below the level of S3, S2, S1 foramina and one side of sacroiliacjoint. RESULTS: Stress was mainly distributed above S1. Sacroiliac joint stress and straindid not increase significantly when resection involved the S2 and S3 foramina. As the loadincreased, the stress and displacement of the pelvis increased too. Within the sacroiliacjoint, the average stress increased 4.3 times with transection cephalad to the S1 foraminaand 2.1 times with transection caudal to the S1 foramina on the sacral side of the joint byFEM. On the iliac side of the sacroiliac joint, the stress only increased 67.7％and 87.5％.The axial stiffness of the pelvis was decreased 50-60％. With expanded resection stressincreased on the sacral side, while a sudden decrease of approximately 54.3％wasobserved on the iliac side. After excision of the sacral portion of the sacroiliac joint, theintrajoint stress increased on both the sacral and the iliac side. The residual ilium collapsedand moved medially towards the remaining sacrum. CONCLUSIONS: The componentabove S1 is the most important part of stress transduction within the sacroiliac joint. Afterexcision above the foramina of S1, the physiological load bearing ability of sacrum washarmed critically, which may result in fracture with normal activity.Part 3OBJECTIVE: To design a new kind of sacrum prosthesis, which is able to connectlumbar and pelvis, bear the body weight and recover the physiological stress transduction. METHODS: A finite element model of pelvis was developed based on the CT image dataof human pelvises; the main stress distribution was calculated. The main stresstransduction structure showed. The three dimensional numerical model of A new sacrumprosthesis was designed simulating this structure and was measured by finite elementanalysis method. 19 three dimensional numerical model based on CT image data ofdifferent patients was developed and measured simulating reconstruction with the newprosthesis after total sacrectomy. RESULTS: The new sacrum prosthesis was made up ofseveral parts, the sizes of every parts was due to patient’s hight and resection degree. Byfinite element analysis, the resected pelvis which was reconstructed with the prosthesisseemed to be a stable structure, the prosthesis restores the stress transduetion prior tosacrectomy. No stress sudden change was detected. CONCLUSIONS: The new designedsacrum prosthesis has the ability of reconstructing pelvises after sacreetomy. Compared tothose already reported, it is more stable, and has the advantage of recovering thephysiological stress transduction.Above all, we concluded that the component above S1 is the most important part ofstress transduction within the sacroiliac joint, after excision above the foramina of S1, thephysiological load bearing ability of sacrum was harmed critically, which may result infracture with normal activity. A new sacrum prosthesis should be encouraged aftersacrectomy to recover the physiological stress transduction. The new sacrum prosthesisdesigned now has the ability to bear the body weight effectively and the stress transductionrecovered with a stable pelvis.更多还原