四维有限元骨承载力分析技术在判断长管骨愈合程度中的应用

目的利用四维有限元骨承载力分析的方法，对于长管骨骨折术后患者采用双腿平行CT扫描、双腿几何建模、有限元分析的方法，通过与健侧肢体相同部位的对比分析，根据时间轴上的变化趋势，判断目标骨段骨愈合的程度，辅助诊断长管骨的骨愈合、骨延迟愈合和骨不连。 方法选择2014年到2017年间，临床诊断骨延迟愈合的26例病例进行了系统随访。在骨愈合不同阶段的CT数据进行三维建模，材料赋值，建立下肢长管骨的三维有限元模型，模拟仿真计算目标骨段承载受力状况，通过有限元分析软件，进行单轴压缩实验的仿真，分析双腿目标骨段的受载荷情况。结合米塞斯应力最大值及载力-位移曲线下总面积进行比值分析，作为观察骨愈合程度的指标，对于临床诊断进行二次修正，并观察最终临床愈合结果。 结果所有病例均获得2~4年的随访，平均随访时间3.4年。临床诊断骨延迟愈合完整病例26例，对26例病例采用有限元骨承载力分析法共分析54次，修正诊断为：6例（23.1%）病例判定骨愈合；16例（61.5%）病例判定骨愈合不良；4例（15.4%）病例判定骨不连。利用米塞斯应力最大值及载力-位移曲线下总面积进行比值分析，并进行卡方检验，差异无统计学意义。通过Fisher精确概率检验法得到P=0.170，具有统计学意义，两种方法存在非随机相关性。 结论采用有限元骨承载力分析的技术，可以三维定量分析骨折端的骨愈合程度，结合时间轴上变化规律的描述，可以给骨不连和骨延迟愈合的临床诊断提供一个相对客观的诊断依据。该方法也较好的观察到，高能量损伤的骨愈合过程难以按照经典骨愈合理论的进程演变，通常其骨愈合所需的时间更长，但能显示出其缓慢的愈合趋势，应用前景广阔。     

距骨颈骨折螺钉固定的三维有限元分析

目的 通过三维有限元法对距骨颈骨折不同螺钉内固定方式进行对比评价,比较不同内固定方式生物力学稳定性,为临床应用提供理论依据.方法 利用CT扫描数据,根据距骨颈骨折不同的内固定方式,建立距骨颈骨折内固定三维有限元模型,研究不同内固定von Mises应力分布和骨折面接触压力及张开位移,分析骨折固定后生物力学稳定性.结果 获得距骨颈骨折不同内固定固定有限元模型,静止站立和踝关节背伸时,不同内固定生物力学稳定性不同,双螺钉由前向后固定螺钉的应力及骨折面张开位移较小,骨折面压力较大.结论 利用双螺钉由前向后固定距骨颈骨折,可以取得较好的生物力学稳定性.     

膝关节三维有限元分析

有限元分析是在工程科学技术领域广泛应用的数学物理方法,是解决复杂工程学问题的必备工具之一.将有限元分析应用于人体生物力学研究,已显示出极大的优越性.通常的力学试验手段基本上不直接应用于人体,其试验结果并不十分准确;有限元分析则可通过对实验条件的控制,更准确地模拟体内的力学情况.对人体力学行为进行有限元数值模拟已成为深化对人体认识的一种有效手段.该文对膝关节三维有限元分析的近期研究进展进行综述,讨论在临床应用中的实际意义,并总结目前有限元分析在膝关节生物力学研究中存在的不足.     

下颌骨截骨整形手术三维有限元模型的建立

目的：为研究下颌骨截骨整形手术的生物力学原理,建立了生物力学相似性较高的无牙下颌骨和颞下颌关节三维有限元模型。方法：以颅颌面系统正常的女性青年志愿者为标本,经过薄层CT断层扫描得到DICOM格式文件,经Mimics和Ansys软件建模,采用只受拉的Link10单元模拟下颌韧带和咀嚼肌约束,采用接触单元对关节窝进行约束。结果：建立了包括颞下颌关节、肌肉和韧带的正常下颌骨三维有限元模型。可根据实验设计建立实验分模型。结论：提高了模型的相似性,为进一步研究下颌角截骨整形生物力学奠定了基础。     

骨水泥量及分布对椎体成形术后相邻椎体生物力学影 响的三维有限元分析

目的利用三维有限元分析骨水泥量及分布对相邻椎体生物力学的影响。方法通过CT数据,利用Mimics10.0、Geomagic studio 11.0、Hyper Mesh l1.0、Abaqus 6.9有限元分析软件,建立骨质疏松性椎体模型,根据骨水泥量及分布方式建成有限元模型,施加载荷,测量相邻椎体应力分布变化情况。结果垂直载荷下,T12椎体皮质骨等效应力在单侧2 ml骨水泥灌注中较高为29.49 MPa;下终板所受应力在单侧偏中4 ml骨水泥灌注中较高为3.93 MPa。L2皮质骨等效应力在单侧骨水泥灌注较高为15.29 MPa;上终板所受应力在单侧偏中2 ml骨水泥灌注中较高为4.53 MPa。侧屈载荷下,T12椎体皮质骨所受等效应力在单侧偏中4 ml骨水泥灌注较高114.83 MPa;下终板所受应力在双侧骨水泥4 ml灌注中较高为8.62 MPa。L2椎体皮质骨所受等效应力在单侧偏中4 ml骨水泥中较高为96.41 MPa;上终板所受应力在单侧偏中4 ml骨水泥灌注中较高为9.80 MPa。旋转载荷下,T12椎体皮质骨所受等效应力在单侧2 ml骨水泥灌注中较高为119.42 MPa;下终板所受应力在单侧2 ml骨水泥灌注中较高为8.77 MPa。L2椎体皮质骨所受等效应力在单侧2 ml骨水泥灌注中较高为146.31 MPa;L2上终板所受应力在单侧2 ml骨水泥灌注中较高为7.84 MPa。结论骨水泥量及分布是相邻椎体发生骨折的一个重要因素,但与椎体所受力学载荷方向也密切相关。     

单侧骨皮质缺损对长管状骨生物力学的影响

目的探讨长管状骨骨干不同大小的单侧骨皮质缺损对长管状骨生物力学性质的影响。方法取76根三黄鸡胫骨,随机分7组(1.5mm组n=11,2.0mm组n=9,2.5mm组n=13,3.0mm组n=12,3.5mm组n=8,4.5mm组n=11,皮质完整组即正常对照组n=12),于后侧骨皮质造成直径分别为1.5～4.5mm的环形骨缺损,进行三点弯曲单一实验,皮质完整组作为正常组对照。结果缺损直径为1.5mm及2.0mm组鸡胫骨达到结构破坏时的最大载荷与正常组差异无统计学意义(P=0.824,0.865),2.5mm、3.0mm、3.5mm组的最大载荷较正常组降低14%左右,差异有统计学意义(P=0.015,0.010,0.021);4.5mm组较正常组降低23%左右,差异有统计学意义(P=0.001)。结论单侧皮质缺损直径在长管状骨外径的(22.6±1.4)%以内时,不影响其抗弯曲性能;当其超过长管状骨外径的(29.4±2.1)%时,将降低长管状骨的抗弯曲性能,但降低的幅度跟缺损大小并不完全呈正比。     

骨质疏松性椎体骨折骨水泥强化术后骨水泥不同分布位置的三维有限元分析

目的 采用三维有限元分析研究骨质疏松性椎体骨折骨水泥强化术后骨水泥不同分布位置的生物力学改变.方法 选择6例健康成人志愿者,将其腰椎薄层CT平扫数据导入Mimics软件中,建立L1椎体骨质疏松性模型及前方、后方、右侧方填充骨水泥模型共4组.将模型导入Ansys软件中进行压力载荷模拟,记录角位移及最大压力.结果 站立位、...     

跟骨三维有限元模型的建立与静态分析

目的 建立一个基于健康人体的跟骨三维有限元模型,静态分析双足站立相时跟骨内部的生物力学特性,探讨跟骨骨折疼痛的内外侧应力不均衡因素.方法 选取1名健康男性志愿者,年龄28岁,体重64kg.采用16排螺旋CT对足部沿横断面连续扫描,将符合DICOM 3.0标准的CT断层图像导入MIMICS10.1中,设定阈值为226～3071 Houfield unit,确定方位后经手动编辑、区域增长、形态学操作及空洞处理等,生成足部的三维模型,从整个足部模型中提取跟骨模型.对跟骨进行面网格的优化处理后,导入ANSYS10.0中得到体网格模型.根据CT断层图像的灰度值完成模型材质的添加,生成最终的三维有限元模型.模拟研究对象双足静止站立的状态,距下关节面在整个分析过程中被全约束,自足跟及跟腱附着点处对模型分别施加垂直向上的320 N和160 N载荷,观察跟骨的Vonmises应力分布.结果 MIMICS软件能够迅速建立更为精确的有限元模型,当垂直载荷作用于跟骨后,跟骨内、外侧存在一定的应力不均衡因素.跟骨的外侧结构是明显的薄弱区域,随着跟骨外侧壁的应力增加,导致继发外侧畸形,压迫腓骨长短肌及跟骰关节产生疼痛.结论 创建的跟骨三维有限元模型,经验证是一个较为精确的正常跟骨三维模型,可用于理解跟骨内部的应力分布变化.     

长管状骨骨巨细胞瘤的影像诊断分析

[目的]分析长管状骨骨巨细胞瘤的影像学表现,探讨其影像学特点与病理之间的关系。[方法]分析31例由手术病理证实的长管状骨骨巨细胞瘤的影像学表现。[结果]由于病理上瘤体组织成分的不同,长管状骨骨巨细胞瘤的影像学表现为偏心性、膨胀性溶骨性骨质破坏,可呈"皂泡状"改变。[结论]大部分长管状骨骨巨细胞瘤具有较典型的影像学表现,X线平片可从宏观上显示病变;CT可从横断面显示病灶的骨质破坏程度、灶周软组织改变、病灶内部的CT值;MRI可以多方位成像,全面显示病灶的范围、灶周软组织的受累情况;三者的影像学表现综合分析对长管状骨骨巨细胞瘤的诊断有重要价值。     

半月板三维有限元模型建立及力学分析

目的:建立正常膝关节及半月板三维有限元模型,较真实模拟膝关节及半月板的解剖形态及特点,通过初步有限元生物力学分析验证模型的有效性,并阐释半月板的部分生物力学机制。方法:利用CT和MRI扫描一健康男性志愿者膝关节获得其图像信息,导入至Mimics 10.01及Geomagic Studio软件构建膝关节各组织结构三维模型,利用ANSA软件对结构模型进行组合建立完整的膝关节模型,并对模型进行网格划分,最终建立了完整膝关节三维有限元模型。最后将有限元模型导入到ANSYS软件中,设置材料属性、建立边界条件和施加载荷,进行有限元分析,验证模型有效性,并分析半月板的生物力学特性。结果:所建立的模型包含膝关节骨、关节软骨、半月板及主要韧带结构,能有效模拟膝关节及半月板的解剖形态及特点。内侧半月板接触面积为771.05 mm2,外侧半月板接触面积为634.31 mm2,内外侧半月板接触面积比为1.216。内外侧半月板的应力分布均匀,但内侧半月板所受应力高于外侧半月板,其峰值应力分别出现在内侧半月板后角及外侧半月板前角,其峰值应力为4.11 MPa。半月板最大位移位于其体部,内侧较外侧形变更大,最大位移形变值为0.33 mm。所获得的力学分析结果于文献相一致,验证了模型的有效性。结论:本研究所建立的膝关节及半月板有限元模型具有有效性,可为半月板撕裂及半月板切除术等有限元分析研究提供有效的模型。所获得的有限元分析结果能够阐释半月板的部分生物力学机制,为临床半月板损伤和治疗提供理论指导。     

股骨质量对人工髋关节置换之影响的三维有限元分析

目的　探讨股骨质量对非骨水泥型人工髋关节置换术后稳定性及应力变化的影响 ,论证三维有限元分析作为个体化假体选择临床前评价手段的可行性及价值。方法　采用三维有限元分析模型 ,对骨质正常骨与骨质疏松骨进行股骨应力、界面位移的计算 ,并与实验值比较。结果　正常骨的股骨应力比疏松骨的股骨应力大 ,非骨水泥有肩托假体 (NCC)能增加股骨矩处压应力 ,但同时大粗隆处应力减少。骨质量不同对应力改变的趋势没有影响。骨质量差者 ,界面位移大。三维有限元分析结果与生物力学实验结果比较接近。结论　三维有限元分析是目前被认为可以根据病人的股骨质量进行个体化假体选择的有前途的研究方法。骨质量是影响假体的初始稳定性及应力变化的因素     

基于中国数字人CT数据重建膝关节有限元模型

目的建立精确的数字力学人膝关节模型。方法采用中国数字人男1号数据,使用经Materialise公司授权的MIMICS8.1医学图像重建软件进行三维有限元建模,其结果导入有限元系统进行处理。结果建立起形态学高度拟真的膝关节模型。结论数字力学人模型可进行有限元计算,其精度能更好地满足数字化医学对计算机模拟论证的要求。     

The Biomechanical Influence of Defected Cartilage on the Progression of Osteochondral Lesions of the Talus: A Three-dimensional Finite Element Analysis

Objectives

Osteochondral lesions of the talus (OLTs) are common injuries in the general population. Abnormal mechanical conditions applied to defected cartilage are believed to be the culprits to deteriorating OLTs. This study aims to investigate the biomechanical effects of defect size of talar cartilage on OLTs during ankle movements.

Methods

A finite element model of the ankle joint was created based on the computed tomography images of a healthy male volunteer. Different defect sizes (S = 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, and 2.0 cm²) of talar cartilage were modeled to simulate the progression of OLTs. Mechanical moments were applied to the model to generate different ankle movements, including dorsiflexion, plantarflexion, inversion, and eversion. The effects of varying defect sizes on peak stress and its location were evaluated.

Results

The maximum stress on the talar cartilage increased as the area of the defect enlarged. Additionally, as the defect size of OLTs increased, the areas with peak stress on talar cartilage tended to move closer to where the injury was located. High stresses were present in the medial and lateral areas of the talus at the neutral position of the ankle joint. The concentrated stresses were mainly located in the anterior and posterior defect areas. The peak stress in the medial region was higher than on the lateral side. The order of peak stress from highest to lowest was dorsiflexion, internal rotation, inversion, external rotation, plantar flexion, and eversion.

Conclusions

Osteochondral defect size and ankle joint movements significantly modulate the biomechanical features of the articular cartilage in osteochondral lesions of the talus. The progression of osteochondral lesions in a talus deteriorates the biomechanical well-being of the bone tissues of the talus.     

Biomechanical Evaluation of Oblique Lumbar Interbody Fusion with Various Fixation Options: A Finite Element Analysis

ObjectiveThe aim of the present study was to clarify the biomechanical properties of oblique lumbar interbody fusion (OLIF) using different fixation methods in normal and osteoporosis spines.MethodsNormal and osteoporosis intact finite element models of L₁–S₁ were established based on CT images of a healthy male volunteer. Group A was the normal models and group B was the osteoporosis model. Each group included four subgroups: (i) intact; (ii) stand‐alone cage (Cage); (iii) cage with lateral plate and two lateral screws (LP); and (iv) cage with bilateral pedicle screws and rods (BPSR). The L₃–L₄ level was defined as the surgical segment. After validating the normal intact model, compressive load of 400 N and torsional moment of 10 Nm were applied to the superior surface of L₂ to simulate flexion, extension, left bending, right bending, left rotation, and right rotation motions. Surgical segmental range of motion (ROM), cage stress, endplate stress, supplemental fixation stress, and stress distribution were analyzed in each group.ResultsCage provided the minimal reduction of ROM among all motions (normal, 82.30%–98.81%; osteoporosis, 92.04%–97.29% of intact model). BPSR demonstrated the maximum reduction of ROM (normal, 43.94%–61.13%; osteoporosis, 45.61%–62.27% of intact model). The ROM of LP was between that of Cage and BPSR (normal, 63.25%–79.72%; osteoporosis, 70%–87.15% of intact model). Cage had the minimal cage stress and endplate stress. With the help of LP and BPSR fixation, cage stress and endplate stress were significantly reduced in all motions, both in normal and osteoporosis finite element models. However, BPSR had more advantages. For cage stress, BPSR was at least 75.73% less than that of Cage in the normal model, and it was at least 80.10% less than that of Cage in the osteoporosis model. For endplate stress, BPSR was at least 75.98% less than that of Cage in the normal model, and it was at least 78.06% less than that of Cage in the osteoporosis model. For supplemental fixation stress, BPSR and LP were much less than the yield strength in all motions in the two groups. In addition, the comparison between the two groups showed that the ROM, cage stress, endplate stress, and supplemental fixation stress in the normal model were less than in the osteoporosis model when using the same fixation option of OLIF.ConclusionOblique lumbar interbody fusion with BPSR provided the best biomechanical stability both in normal and osteoporosis spines. The biomechanical properties of the normal spine were better than those of the osteoporosis spine when using the same fixation option of OLIF.     

Biomechanical Evaluation of Spinal Column after Percutaneous Cement Discoplasty: A Finite Element Analysis

ObjectiveTo compare the biomechanical properties of percutaneous cement discoplasty (PCD) in the spinal column between different implant‐endplate friction.MethodsA validated L3‐Scarumfinite element (FE) model was modified for simulation. In the PCD model, the L4/5 level was modified based on model 1 (M1) and model 2 (M2). In M1, the interaction between bone cement and endplate was defined as face‐to‐face contact with a friction coefficient of 0.3; in M2, the contact was defined as a Tie constraint. 7.5 N m moments of four physiological motions and axial load of 15, 100 and 400 N preload were imposed at the top of L3. The range of motion (ROM) and interface stress analysis of endplates, annulus fibrosus and bone cement of the operated level were calculated for comparisons among the three models.ResultsThe ROM of M1 and M2 increased when compared with the intact model during flexion (FL) (17.5% vs 10.0%), extension (EX) (8.8% vs −8.8%), left bending (LB) (19.0% vs −17.2%) and left axial rotation (LR) (34.6% vs −3.8%). The stress of annulus fibrosus in M1 and M2 decreased in FL (−48.4% vs −57.5%), EX (−25.7% vs −14.7%), LB (−47.5% vs −52.4%), LR (−61.4% vs −68.7%) and axis loading of 100 N (−41.5% vs −15.3%), and 400 N (−27.9% vs −27.3%). The stress of upper endplate of M1 and M2 increased in FL (24.6% vs 24.7%), LB (82.2% vs 89.5%), LR (119% vs 62.4%) and axis loading of 100 N (64.6% vs 45.5%), and 400 N (58.2% vs 24.3%), but was similar in EX (2.9% vs 0.3%). The stress of lower endplate of M1 and M2 increased in FL (170.9% vs 175.0%), EX (180.8% vs 207.7%), LB (302.6% vs 274.7%), LR (332.4% vs 132.8%) and axis loading of 100 N (350.7% vs 168.6%), and 400 N (165.2% vs 106.7%).ConclusionPercutaneous cement discoplasty procedure could make effect on the mobility or stiffness. The fusion of bone cement and endplate might have more biomechanical advantages, including of the decreasing rate of implant subsidence and dislocation, and the increase spine stability.     

畸形愈合的跟骨在不同步态位相应力分布的三维有限元研究

目的 对后关节面压缩的跟骨与距骨在步态过程中的应力变化进行生物力学分析。方法 在跟骨有限元模型上切割部分后关节面,模拟跟骨骨折后的后关节面压缩畸形。利用模拟畸形愈合的跟、距骨有限元模型模拟跟距骨在步态过程中三个位相(落地相、中立相、起步相)时的受力状况,进行有限元计算,并与正常状况进行分析。结果 获得了模拟畸形愈合的跟、距骨在三个位相时的应力分布和应力增高区,与正常状况时明显不同。结论 模拟畸形愈合的跟、距骨的应力分布变化对临床研究有重要意义,可对许多临床病理现象做出解释。     

下颌骨牵张成骨的有限元模拟

目的：建立下颌骨牵张成骨的有限元模型,以了解下颌骨牵张成骨形变发生的生物力学基础和形变规律。方法将下颌骨CT数据导入Mimics 10.1,按临床设计的截骨线位置进行模拟截骨,然后将数据输入Magics 9.9中进行模型优化。输入Ansys 12.0建模,并进行下颌骨牵张成骨的模拟。结果牵张成骨的位移变化、应力及软组织改变均可直观有效地模拟。结论有限元分析可以总结手术效果,分析应力分布及软组织阻力方向,提出治疗过程的改进意见。     

臼杯假体高度对臼杯-骨界面应力应变影响的有限元分析

目的探究臼杯假体模拟植入Crowe Ⅱ/Ⅲ型DDH髋臼的不同高度时臼杯-骨界面间应力和应变分布特征。 方法基于3位Crowe Ⅱ/Ⅲ型DDH患者髋关节的CT扫描数据,利用计算机软件作髋臼三维建模,在距髋臼下缘连线垂直高度为15、21、30 mm处分别模拟植入臼杯模型,并转化为三维有限元网格模型,施加静力载荷,记录臼杯-骨界面的应力和应变数据,行配对t检验或Wilcoxon符号秩检验分析各组最大应力及应变的差异。 结果3组臼杯模型在距髋臼下缘连线垂直高度为21 mm处的最大应力值最小,分别为患者A 10.03 Mpa、患者B 17.67 Mpa和患者C 14.99 Mpa。在安装高度为15 mm和30 mm处,臼杯的最大应力值分别为患者A 20.64、12.03 Mpa,患者B 22.06、23.02 Mpa和患者C 34.72、17.88 Mpa。对15、21、30 mm处骨质、臼杯的最大应力及应变行两两配对检验显示各组差异无统计学意义(校正后P>0.0167)。不同安装高度下臼杯假体及假体周围骨组织应变量没有明显分布规律。 结论对于Crowe Ⅱ/Ⅲ型DDH患者行全髋关节置换术,适当上移臼杯旋转中心能减少臼杯假体最大应力。