人工股骨柄形状和表面处理对置换术后假体和人体股骨应力分布影响的有限元分析

目的建立人工髋关节置换术后的三维有限元模型,分析研究人工股骨柄、骨水泥和人体股骨的应力分布。方法应用三维重建软件及Pro/Engineer建模软件和ABAQUS有限元分析软件计算分析人工股骨柄中空形状和柄部预处理范围对置换术后假体和人体股骨应力分布的影响。结果(1)倒立圆锥形中空特征的骨水泥固定型股骨柄的应力最小,其股骨柄周围骨水泥近端应力亦较低。(2)具有上涂层骨水泥的股骨柄可使骨水泥近端产生的应力减小,且股骨柄与骨水泥二者之间的剪力和相对滑动亦较小。(3)随着非骨水泥固定型股骨柄微孔涂层范围的增加,人体股骨上的应力范围下移,人体股骨近端的应力减小。结论(1)采用倒立圆锥形中空特征的人工股骨柄有助于降低人体股骨近端与假体接触区的应力遮挡效应。(2)采用股骨柄上涂层骨水泥的方法,可增强股骨柄与骨水泥界面的结合强度,有利于降低人工髋关节置换术后的假体松动。(3)非骨水泥固定型股骨柄微孔涂层范围对人体股骨的应力有明显的影响,微孔涂层范围过大不利于保持适中的人体股骨的应力和股骨柄的固定。     

人工髋关节置换前后股骨及假体的生物力学分析

目的:研究人工髋关节置换前后股骨及假体的应力分布以及假体设计参数对应力的影响。方法:建立股骨和假体有限元模型,分析在步行峰值关节载荷和主要肌肉载荷作用下,完整股骨和置换后股骨及假体的应力水平。结果:完整股骨中上部内侧受压应力,外侧受张应力,中下部外侧受压应力,内侧受张应力,股骨应力峰值位于中下部;置换后股骨受力总体模式不变,近端应力遮挡显著。随颈干角增加,假体及股骨应力水平降低;柄长对假体应力影响不大,股骨上的应力随柄长增大略有增加。结论:假体设计时可适当增大颈干角,在骨组织条件允许的情况下可适当增加假体柄长,以减轻术后的应力遮挡效应。     

髋关节置换前后不同步态下股骨应力分布

目的探讨人工髋关节置换(total hip replacement,THR)前后慢走及上下楼梯两种不同步态下股骨的生物力学性能,为髋关节假体的优化设计和制造提供理论基础。方法建立人工髋关节股骨的三维有限元模型,并进行有效性验证;计算慢走和上下楼梯时THR前后股骨的应力分布及应力遮挡率。结果慢走运动时,THR前股骨应力由近端到远端逐渐递增,在股骨中下段达到最大,最大应力为90.6 MPa;THR后股骨出现应力遮挡现象,股骨的应力幅值有所下降,最大应力为82.5 MPa,股骨近端假体周围大转子附近股骨遮挡率最大,总体遮挡率为14.9%~99.0%。此外,假体颈部出现过大的应力集中现象。上下楼梯运动时,股骨应力分布的变化规律与慢走运动时大体相似,但应力遮挡效应更为明显。结论植入假体后,上下楼梯时股骨近端出现较大应力遮挡,并且假体自身出现过大应力集中,会影响THR手术质量,建议病人在术后应尽量减少关节角变化较大的运动。     

全髋表面置换术后与正常股骨近端生物力学比较

目的 通过三维有限元方法研究全髋表面置换术后股骨近端骨质区应力分布的变化。方法 采用64排螺旋CT扫描获得正常股骨近端图像数据,重建股骨近端的三维有限元模型,对金属对金属全髋表面置换术后股骨近端和正常股骨近端应力分布进行量化研究,分析术后生物力学环境的变化。结果 髋关节表面置换术后,股骨头近端上、前、后、下方4个区域均出现明显应力遮挡,应力峰值分别为0.60、0.57、0.66、0.79 MPa,遮挡率分别为99.80%、99.16%、98.92%、96.66%。股骨头远端大部分区域出现了应力增加,其中应力遮挡只出现在股骨头远端的后方区域,遮挡率为4.92%。术后股骨颈近端前方区域出现了应力增加,在上、下、后方区域出现了应力遮挡,遮挡率分别为16.48%、22.75%和7.83%;股骨颈远端下方区域出现了应力增加,其余区域出现应力遮挡。大粗隆区出现应力增加9.22%;小粗隆区域和股骨颈基底区出现应力遮挡,遮挡率分别为2.49%、14.44%。结论髋关节表面置换术后股骨近端大部分区域的应力分布和正常股骨相比非常接近,应力传递接近生理状态,可有效避免术后股骨近段明显的应力遮挡,同时保留了骨量,有利于患者正常的生理活动。     

全髋关节置换术对股骨近端骨重建的影响

目的 采用Wolff骨重建理论分析全髋关节置换（total hip arthroplasty,THA）对股骨近端骨重建进程的影响。方法 根据骨重建控制方程,利用Python语言编写骨重建程序。在ABAQUS软件中分别建立术前股骨模型与术后股骨及假体有限元模型。对比THA手术前后骨重建进程,分析假体植入对THA术后中远期股骨力学性能的影响。结果 假体植入后,股骨近端应力持续降低,受力点由股骨头转移到假体,出现明显的应力遮挡现象。应力遮挡区域内骨丢失现象严重。股骨干皮质骨变薄,应力遮挡有所缓解。假体底端内侧受挤压,应力显著高于外侧,此处骨质分布不均。结论 THA术后股骨近端内侧出现明显的应力遮挡,导致骨丢失,造成假体松动;假体底端两侧应力水平存在差异,引起骨质分布不均,导致假体与股骨配合不紧密,造成术后患者大腿中段的疼痛。     

人工股骨置换术后股骨再造预测

以骨截面面积吸收率和抗弯截面模量损失率反应力遮挡效应，采用骨再造理论和有限元(Finite element，FEM)相结合的方法，用计算机模拟人工股骨植换术后股骨的再造行为，从而定量的分析人工股骨头对股骨的应力遮挡效应。骨表面再造采用BRSS97程序。有限元模型采用正常股骨的受力状态为模型一，带颈领的人工股骨头骨水泥固定骨受力状态为模型二。结果表明，人工股骨头对骨产生的应力遮挡，股骨发生骨吸收，人工假体柄中段近端区域骨吸收严重。其骨截面积吸收最大，其截面吸收率最大为31．33％，抗弯截面模量损失率最大为54．58％。     

人工股骨柄的力学研究现状

背景：临床表明,全髋关节重建涉及假体、骨水泥和股骨整体的应力分布,针对减少各个组件的应力以减少置换关节失效风险研究有了很大的进展。 目的：对髋关节置换后各组件应力分布的研究现状及进展作一综述。 方法：应用计算机检索CNKI,EI Village和ELSEVER数据库中2001-01/2011-01关于髋关节置换和股骨柄应力的文章,在标题和摘要中以“股骨柄,应力,全髋关节置换”或“stem,prosthesis,stress,Total Hip Replacement”为检索词进行检索。入选34篇文献和2本书籍进行综述。 结果与结论：人工髋关节固定需亟待解决的关键问题是髋关节置换后各组件应力非均匀传递而引起的界面剪滞效应,并将最终导致界面松动失效。研究股骨-柄松动原因和增强股骨-柄界面的自锁能力,应是提高人工髋关节的稳定性和延长置换后髋关节寿命的发展方向。     

影响THA术后股骨近端应力遮挡大小的因素

全髋关节置换术(THA)术后股骨近端的应力遮挡效应是引起假体周围骨丢失的原因之一,在骨水泥和非骨水泥假体中都存在这一现象[1,2],骨丢失可能会引起股骨假体机械性失败、假体松动、假体周围骨折、翻修手术难度增加等一系列的问题[2],因此研究如何减少应力遮挡效应有重要意义.……     

人工全髋关节置换术对天然股骨生物力学行为的影响

目的研究人工全髋关节置换术后股骨的变形及应力改变,同时研究关节置换术对股骨振型及固有频率的影响。方法选取1名正常男性青年进行股骨段CT扫描,构建正常股骨和术后股骨的有限元模型,对其进行步态情况下的生物力学行为分析、模态分析。结果 (1)关节置换术后假体柄部有明显的应力集中,并产生了应力遮挡;(2)术后股骨的峰值应力增大到原来的4.36倍;(3)约束模态的固有频率明显高于自由模态;(4)振型阶次越高,术后股骨与正常股骨固有频率的差距越大;(5)股骨的振型主要为弯曲和扭转,且置换前后振型变化不大。结论假体的植入改变了股骨原有的力学结构特性。在假体设计方面,必须考虑到股骨的振动特性,避免共振带来的假体松动。     

髋关节的几何参数测定

髋关节是人体的重要关节。在人工髋关节置换中,假体与股骨间匹配程度是影响其长期疗效的重要因素［１－４］Ｅｎｇｈ［２］等发现假体与股骨间匹配紧密的患者Ｄ’Ａｕｂｉｇｎｅｓｃａｌｅ得分较高。Ｓａｌｚｅｒ［５］等在对三种非骨水泥假体的研究发现,在下沉１０ｍｍ以上的假体中２５％与髓腔不匹配有关。Ｃｒｏｗｎｉｎｓｈｉｅｌｄ［６,７］用三维有限元分析来估算人工关节柄长度横截面等几何尺寸范围以及骨水泥和假体柄应力分布,发现将股骨假体柄长度从１００增加至１３０时,最大拉伸应力增加３１％,同时在骨水泥中的最大压应力…     

钛合金人工关节柄烧结复合生物活性玻璃陶瓷涂层的研究

采用两步涂烧法在钛合金表面制备出防组织液渗透,结合强度高,生物相容性好的复合生物活性陶瓷涂层,适合于改善人工髋关节柄部的骨结合特性。     

三维CT术前测量儿童发育性髋关节发育不良的研究

目的 通过三维CT对发育性髋关节发育不良（DDH）儿童髋关节进行三维重建,探讨三维CT对DDH患儿的临床价值。方法 收集2016年1月~2018年12月重庆医科大学附属儿童医院进行术前三维CT重建的DDH患儿12例,在三维重建模型上对患儿髋关节的相关结构进行测量。结果 通过对12例患儿术前髋关节三维重建模型进行观察与测量,患儿平均髋臼缺损宽度为（39.06±3.11）mm,平均髋臼缺损深度为（8.69±0.57）mm。选择缝匠肌骨瓣修补患儿髋臼缺损,术后髋臼缺损皆获得明显改善。结论 三维CT能够从多个方位观察髋关节结构,更直观、更全面的观察到髋关节形态学的变化,在三维CT模型上可直接测量髋臼缺损的大小,更有效的指导手术选择及临床工作。     

人工髋关节活体有限元建模及力学分析

背景：有限元分析最为广泛地应用于人工髋关节置换的研究,能够反映人工髋关节置换前后的应力分布情况。 目的：通过CT扫描图像建立人工髋关节置换后的三维有限元模型,分析假体和股骨的力学分布,提供研究活体内假体的评估方法。 方法：选非水泥型人工髋关节假体置换后患者1例,64排CT扫描髋关节,通过三维建模软件建立三维有限元模型,加载载荷1 500 N,分析假体和股骨的应力分布,并与体外建模和正常股骨有限元模型比较。 结果与结论：应用患者人工髋关节置换后CT扫描图像建立的三维有限元模型,加载后应力主要分布在股骨干上端1/3处,在股骨假体柄颈结合处,假体外侧,假体的远端与股骨接触处,是假体置换后应力在体内传递的真实反映。结果说明活体髋关节建模优于体外建模,不改变假体在体内的位置,人工髋关节活体建模是假体评估新方法。     

髋关节骨内植入体模型的创建

目的利用CT/MRI医学影像数据,在建立人体髋关节三维模型的基础上,运用Mimics软件中MedCAD模块创建个性化的人体髋关节植入体模型。方法应用Mimics软件,对髋关节组织扫描图像进行处理,根据病体使用MedCAD模块创建植入体CAD模型,然后选择合适的植入体将其放入病体髋关节骨的合理位置上。结果首先创建病体髋关节模型,在此基础上运用Mimics的MedCAD模块在髋骨三维模型上进行植入体的操作,可根据患者的个性化对植入体的大小、形状进行选择或设计,对植入体所放的位置进行定位。结论该研究强调针对不同患者进行个性化的产品研发与设计。依据关节解剖结构的特异性,来创建人体植入体,以符合患者术后关节功能性解剖的需要。     

A radiographic study of hip-joint alignment after prosthetic hip arthoplasty

Postoperative hip alignment was studied on radiographs in cases of total hip arthroplasty (THA) and of Bipolar Head Prosthesis(BHP), both with MX-1. Postoperative anteroposterior-view radiographs of hip joints of patients with a normal hip joint on the unoperated side and without pelvic tilt were used. Thirty-nine THA patients (femoral neck fracture), 26 THA patients (osteonecrosis of the femoral head and osteoarthritis of the hip joint), and 34 BHP patients were selected for this study. Lines and points for measurement of 9 parameters were established on radiographs. The position of the greater trochanter upper edge is 6.5 mm (mean) superior to the femoral head center in the normal hip joint of Japanese, unlike in Caucasians. A femoral head prosthesis should be inserted so that its center and the greater trochanter upper edge are level in order to equalize leg lengths. In BHP cases, the insertion is made so that the greater trochanter upper edge is approximately 4-mm superior to the center of the prosthesis. For further securing of the stem and to equalize leg lengths, stems should be available in 11 diameters from 5-15 mm in 1-mm increments. Postoperative hip alignment in MX-1 THA cases was found to be satisfactory.     

金属对金属人工髋关节的磨损预测

目的发展复杂动态载荷与瞬态运动条件下的球面共型接触硬对硬人工髋关节的磨损预测模型,并用于典型的金属对金属人工髋关节在复杂三维生理运动条件下的磨损预测研究。方法建立有限元模型用于接触力学问题求解,采用固定-跟踪法(fixed-tracked method)完成具有三维欧拉运动的人工髋关节双侧界面动态磨损几何再现及相应的接触与磨损问题模拟的数值交换。结果磨损预测表明,磨损导致金属对金属人工髋关节接触界面几何由球面向非球面过渡,接触区域随磨损周期而增大,接触压力变化趋于平缓、最大接触压力逐渐减小。结论本研究所发展的三维复杂动态、具有双侧界面几何磨损变化的人工髋关节磨损预测模型,能够很好地进行金属对金属髋关节磨损数值预测模拟实验,为认识人工髋关节磨损机理提供了新的方法。     

Pose estimation of artificial hip joint using a single radiographic projection

Total hip joint arthroplasty is commonly used in cases of osteoarthritis and rheumatoid arthritis. A hip joint prosthesis consists of a cup and a stem. The relative pose (position and orientation) of the prosthesis, when the patient is standing naturally, is planned pre-operatively; however, there is no guarantee that the pre-operatively planned pose will be accurate. Prosthesis component malposition, which is inadequate positioning of the acetabular or femoral component, results in limited joint movement and a large prosthetic joint contact area, and this can cause dislocation of the femoral head from the cap. Because the range of motion after total hip joint arthroplasty is determined by the relative pose of the cup and the stem, it is important to know the relative pose after hip arthroplasty. Several pose estimation methods using single-plane fluoroscopy or conventional roentgenography have been proposed. Because a conventional radiograph system is commonly used at small cost, a method using conventional radiograms is desirable for use in a clinical setting. In this study, a pose estimation method using conventional radiography is proposed, and anin vitro experiment is performed to evaluate its accuracy. The rotational errors of the relative pose of the cup with respect to the stem were smaller than 2.3°.     

Finite element analysis of a three-dimensional model of a proximal femur-cemented femoral THJR component construct: influence of assigned interface conditions on strain energy density

A finite element analysis of the stresses in a construct, comprising a three-dimensional model of the proximal human femur in which the stem of a total hip joint replacement was cemented, was performed. The one-legged standing condition was used, with all applied forces on the proximal femur being considered. These forces were the resultant hip joint reaction force and the forces due to the activation of the abductor, ilio-psoas, and ilio-tibialis muscles. The cortical and cancellous bones were assigned anisotropic elastic properties. It was found that the mean value of the strain energy density at each of the regions considered was considerably higher when debonding was considered at both the cancellous bone-acrylic bone cement and bone cement-stem interfaces (represented using surface-to-surface Coulomb friction, coefficient of friction = 0.22) compared to when perfect bonding conditions were taken to exist at these interfaces. The significance of this finding, together with the study limitations, is discussed.     

人工全髋关节置换治疗强直性脊柱炎髋关节强直畸形

背景：目前,人工全髋关节置换是治疗髋关节强直畸形髋关节晚期病变的最佳方案,但置换假体松动一直是置换后棘手的问题,主要与假体的界面应力和假体界面结合强度两方面有关。 目的：总结对强直性脊柱炎髋关节强直畸形患者行人工全髋关节置换的方法及疗效和并发症发生的机制。 方法：电子检索CNKI数据库、万方医学数据库等中文数据库和PubMed,Springer Link等英文数据库1980/2011-12收录的人工全髋关节置换治疗髋关节强直畸形的临床病例研究和相关综述,关键词设定为：髋关节、强直畸形、人工全髋关节置换、假体松动、并发症等,分析人工全髋关节置换治疗髋关节强直畸形的研究进展及髋关节植入后相关并发症的研究进展。 结果与结论：根据患者自身状况进行置换前后评估,选择合适型号、准备不同规格的假体对髋关节强直畸形疗效有促进作用。强直性脊柱炎晚期髋关节骨性强直年轻患者骨增生活跃,新骨可较多地长入假体表面微孔中,因此非骨水泥型假体显示了独特的优势。随着生物型假体设计的进步,尤其具有各种涂层和金属微孔表面人工全髋关节具有多部位负重和紧密匹配的特点,也使其初期的固定较以往的假体更加可靠。近年来该方法取得了很大的进展,但置换后假体的松动以及假体周围关节感染仍困扰着骨科医生和患者。     

Turning strategies during human walking.

The mechanisms involved in rapidly turning during human walking were studied. Subjects were asked to walk at a comfortable speed and to turn toward the instructed direction as soon as they felt an electrical stimulus to the superficial peroneal nerve. Stimuli were presented repeatedly at random over 10- to 15-min periods of walking for turning in both directions. Electromyograms (EMGs), joint angular movements of the right leg, and forces under both feet were recorded. The step cycle was divided into 16 parts, and the responses to stimuli in each part were analyzed separately. Two turning strategies were used, depending on which leg was placed in front for braking. For example, to turn to the right when the right foot was placed in front, subjects generally altered direction by spinning the body around the right foot (spin turn). To turn left when the right foot was in front, subjects shifted weight to the right leg, externally rotated the left hip, stepped onto the left leg, and continued turning until the right leg stepped in the new direction (step turn). The step turn is easy and stable because the base of support during the turn is much wider than in the spin turn, so some subjects used it in all parts of the cycle. Initially, the deceleration of walking is similar to a rapid stopping task, which has been previously examined. The deceleration mechanism involves a sequence of distal-to-proximal activation of muscles on one side of the body (soleus, biceps femoris, and erector spinae). This pattern is similar to the "ankle strategy" used in postural control during forward sway. The control of foot placement in the swing leg and muscle activities for rotating the trunk in the stance leg occurred within a step after the cue. The action of ankle inverters and elevation of the pelvis by activity of gluteus medius may contribute to the control of trunk rotation. This activity was closely related to the timing of the opposite foot strike, independent of the part of the step cycle when the stimulus was applied. In most subjects, the turn was completed without resetting the underlying walking rhythm. This first EMG analysis of rapid turning shows how common strategies for postural sway and stopping can be combined with one of two turning strategies. This simplifies the complex task of turning at a random time in the step cycle.