小腿假肢接受腔计算机三维模型的构建

背景:假肢接受腔作为截肢患者肢体残端和假肢之间载荷传递的惟一通道,是影响假肢适配性的重要部件。假肢接受腔的三维建模是接受腔实用性的关键,可以在测量时得到更准确的数据。目的:建立假肢接受腔计算机三维模型,为接受腔有限元分析提供数据基础,为加工制造接受腔提供可靠的参数。方法:选择1例32岁右侧小腿截肢的男性患者,髋关节各肌力正常,髋18°屈曲挛缩,其他关节活动度正常。根据患者CT和核磁共振扫描图像,采用Mimics10.0软件处理数据,构建假肢接受腔计算机三维模型,准确模拟残肢和接受腔的结构。结果与结论:建立的小腿残肢和接受腔计算机三维模型比较准确地反映了接受腔和残肢的几何特征和外部轮廓。假肢接受腔三维模型的建立有助于提高制作的成功率,从根本上改变传统依靠手工设计、测量、取型、修型等落后的生产模式。     

大腿假肢支撑期有限元分析

目的分析大腿截肢患者的硅胶套材料属性,对支撑期残肢与接受腔之间接触面的力学分布的影响,为大腿假肢适配方案中硅胶套的选取提供参考。方法利用计算机断层扫描技术获取大腿截肢患者残端与接受腔的断层图像,通过影像学信息和工程学方法,分别获取接受腔、硅胶套、残肢、骨骼等结构的三维模型;根据角度变化调整模型,获得初始接触期、负荷反应期、站立中期、站立末期、摆动前期5个时相的组装模型;根据三维动作捕捉系统Motion和Kistler三维测力平台测得的地面反作用力及髋关节角度变化的结果,对5个时相下大腿假肢模型分别进行有限元非线性接触分析;在此基础上,模拟分析了硅胶套不同弹性模量的变化对残肢表面等效应力以及剪切应力分布的影响。结果穿戴不同弹性模量的硅胶套时,残肢所受最大等效应力以及最大剪切应力在初始接触期、负荷反应期、站立中期、站立末期时相时出现在残肢内侧和接受腔口型边缘对应的残肢位置,在摆动前期时相时则出现在残肢内侧、接受腔口型边缘对应的残肢位置和坐骨周围等位置。当硅胶套弹性模量在0.98~2.70 MPa范围内变化时,在摆动前期残肢所受等效应力变化范围为13.85~23.55 k Pa,最大剪切应力变化范围为7.82~13.46 k Pa,而其他时相基本一致。结论硅胶套的力学特性影响大腿假肢残肢与接受腔之间接触面的受力分布,摆动前期残肢所受最大等效应力与最大剪切应力随硅胶套弹性模量变化大,在实际适配过程中需注意。     

大腿残肢步态过程的非线性有限元分析

目的利用三维有限元分析方法研究大腿截肢患者在行走过程中3个不同时相下残肢的生物力学特性,为建立完整的大腿接受腔测量、设计与评估系统提供研究基础。方法首先根据CT图像三维重建大腿截肢患者的骨骼、肌肉软组织和接受腔的三维几何模型;定义软组织为超弹性和线弹性材料属性,并相应建立两个有限元仿真模型;定义残端与接受腔之间的接触关系,约束残肢近端,对模型的远端施加膝关节载荷,模拟步态周期中足跟着地时期、站立相中期、脚尖离地3个时相下大腿残肢-接受腔系统所受载荷;计算分析接触界面上的应力,并对比分析超弹性和线弹性软组织力学特性对接触界面力学行为特性的影响。结果无论线弹性还是超弹性模型,3个时相下大腿残肢-接受腔界面的最大接触压力均在残肢末端达到最大值。超弹性模型3个时相下接触压力峰值分别为55.80、47.63和50.44 kPa;而线弹性模型接触压力的最大值都增加2倍以上,其值分别为149.86、118.55和139.68 kPa。同时通过分析接触面间的径向剪切应力和轴向剪切应力发现,3个时相下接触界面间的应力在残肢末端较集中,在足跟着地到脚尖离地过程中,有部分力通过接受腔后侧缘传递转向接受腔前缘传递。结论不同时相下残肢与接受腔接触界面的压力和剪切应力分布情况不同,在设计接受腔时需要充分考虑其受力特点。     

小腿残肢与接受腔的非线性有限元分析

目的研究残肢与接受腔生机界面力学特性及残端应力情况,为设计和优化小腿接受腔结构、提高其佩戴舒适性提供理论依据。方法针对释压稳定(compression-release stabilization,CRS)接受腔,采用有限元软件ABAQUS分析残肢与CRS接受腔界面应力分布情况,软组织采用非线性超弹性材料Mooney-Rivlin本构模型,得到静止站立中期残肢与CRS接受腔接触界面正应力和剪切应力分布情况,并相应建立髌韧带承重(patellar tendon bearing,PTB)小腿接受腔三维有限元模型,将两者结果进行比较。结果残肢与CRS接受腔界面应力主要分布在胫骨内侧、胫骨外侧和后肌群等承重区,与PTB接受腔模型主要受力区域相似,CRS接受腔残肢末端平均界面应力较PTB接受腔高19 kPa。结论 CRS接受腔具有较好的透气性且应力分布较合理,接受腔形状的不同可改变残肢与接受腔生机界面应力分布,优化其设计有助于提高假肢穿戴舒适性。     

髋离断假肢接受腔-残肢站立期静态有限元分析

目的 利用有限元分析方法研究髋残肢在支撑阶段与髋离断假肢接受腔生机界面的力学特性,为优化、设计髋接受腔结构提供理论依据,为评估髋接受腔舒适度提供研究基础。方法 根据患者残肢CT扫描模型,采用逆向建模的方式,三维重建骨骼、软组织以及接受腔模型。利用有限元方法 研究站立状态下残肢-髋接受腔界面正应力及剪切应力的分布情况,并通过设计压力采集模块系统进行验证。结果 残肢与髋接受腔界面应力主要分布在腰部和残肢底部,位于残肢其余区域的界面应力则分布较为均匀。有限元计算结果和压力采集模块系统测量结果 有较好的符合。结论 为能较好实现髋接受腔功能传递性和安全舒适性,需要充分考虑残肢腰部和底部的受力以及残肢与接受腔的配合度。     

下肢假肢接受腔对残肢肌肉萎缩影响的数值研究

下肢截肢后残肢的肌肉萎缩对患者康复十分不利。为探明残肢肌肉萎缩的生物力学机制,本研究利用大腿截肢患者残肢的磁共振断层影像(MRI),建立了包含肌肉、骨骼以及主要血管的残肢有限元模型,研究分析了下肢假肢接受腔对残肢软组织及血管的生物力学影响。结果发现,旋股外侧动脉降支因挤压而发生的狭窄最为严重,股深动脉的狭窄则相对较小;旋股外侧静脉的降支、股静脉、股深静脉狭窄的程度依次降低,大隐静脉的狭窄程度较为严重。前侧肌群中应力应变最高;下侧肌群在股骨的末端处出现应力集中,并且其他生物力学指标在下侧区域中也相对较高。本研究在一定程度上揭示了接受腔对血管的挤压是导致肌肉萎缩的重要原因,这为进一步研究残肢肌肉的萎缩机制和采取有效的预防措施提供了理论参考。     

小腿假肢接受腔的三维有限元分析

通过建立三维非线性有限元模型来分析小腿假肢接受腔与残肢之间的载荷分布。此模型基于残肢,骨头,软套和接受腔的三维几何形状,考虑界面摩擦滑动条件和软组织的大变形等非线性因素。模型可以预测不同外载下残肢和接受腔之间的压力,剪切力和相对滑动情况。并分析了不同的接受腔形状对载荷分布的影响。     

一体化小腿假肢的三维有限元应力分析

建立一体化小腿假肢和残肢的三维模型，应用有限元分析方法，计算此模型在模拟Mid—Stance步态时相的载荷作用下各节点的应力，从而得到此模型内外表面的应力分布，为一体化假肢设计的CAD＼CAM系统提供理论依据。计算结果表明，接受腔的应力值较小，假腿的应力值较大，高应力区出现在假腿下端及接受腔与假腿的交界区域。     

个体化下肢小腿假肢接受腔设计的生物力学评价技术研究

作为传递体重、固定假肢的部件 ,接受腔对于小腿假肢使用的舒适性和方便程度有决定性的作用。本研究建立了基于有限元应力分析的小腿假肢生物力学评价技术平台 ,实现了小腿残端 /接受腔 3D几何建模与信息交互、三维有限元自动建模及应力分析。 3D模型与信息交互的实现基于得到广泛支持的OpenGL技术 ,有限元模型的构建采用了专门针对小腿残端 /接受腔结构特点的自动建模方法 ,通过构建档案数据库系统作为整个系统的操作平台。该技术平台可与现有的CAD/CAM系统相结合 ,为接受腔的个体化设计提供生物力学定量化依据。其临床应用将改善传统的设计流程 ,提高设计效率。同时 ,它也是未来构建接受腔设计专家 /智能系统的基础。     

建立下肢形态学数据库为匹配术后即装假肢提供参考

文题释义： 术后假肢：现代截肢康复的方法包括手术后安装临时假体，即在完成截肢手术后，医生为患者佩戴合适的临时假体。 大腿影像数据：研究采集的大腿数据包括膝上缘周径、膝上缘5 cm处周径、膝上缘10 cm处周径和膝上缘15 cm处周径，将大腿MRI数据导入3D重建软件，得到大腿截肢范围段表面积、体积。 大腿截肢范围段：为膝关节间隙上10-25 cm。 背景：目前假肢的制作是通过取型、修型、成型3个步骤完成的，由于修型过程是人工完成，与临床技师的经验技术密切相关，制作出来的假肢不美观，接受腔与残肢很难做到全接触。 目的：收集健康志愿者大腿MRI影像数据，评估成人大腿截肢范围段(膝关节间隙上10-25 cm)的对称性；将MRI影像数据建立成数据库，为下肢截肢患者匹配合适的术后即装假肢提供参考数据。 方法：招募40名健康志愿者，采集基本信息：年龄、身高、体质量、膝上缘周径、膝上缘5 cm处周径、膝上缘10 cm处周径和膝上缘15 cm处周径。所有志愿者对试验方案均知情同意，且得到医院伦理委员会批准。对大腿截肢范围进行三维重建，以模型的表面积、体积为参数，对每一例志愿者大腿进行解剖测量，利用三维逆向工程软件对测量结果进行3D偏差分析，完成大腿形态对称性的定量化和可视化分析。 结果与结论：①同体分析：同一个体左右大腿截肢范围段表面积之间的最大百分差异比不超过0.56%(P=0.109)；左右大腿截肢范围段体积之间最大百分差异比不超过1.19%(P=0.182)；三维偏差分析结果显示，最大平均负偏差为-1.47 mm，最大平均正偏差为1.14 mm。40例受试者的3D偏差分布78.02%在2 mm以内，20.97%在2.1-3.0 mm，仅1.01%大于3 mm。②异体分析：三维偏差分析结果显示，最大平均负偏差为-1.97 mm，而最大平均正偏差为1.89 mm。③提示成人双侧大腿截肢范围具有高度的解剖学对称性；当2名成人的膝上缘周径、膝上缘5 cm处周径、膝上缘10 cm周径和膝上缘15 cm处周径分别都相差在2 cm以内时，则认为这2名成人双侧大腿截肢范围段表面轮廓具有高度相似性，与性别、身高和体质量无关。 ORCID: 0000-0001-6838-3042(伍笑棋) 中国组织工程研究杂志出版内容重点：人工关节；骨植入物；脊柱；骨折；内固定；数字化骨科；组织工程     

假肢手接受腔恒力挤压块设计

目的针对假肢手接受腔挤压模块的功能需求,设计一种恒力输出的挤压机构。方法根据正负弹簧刚度抵消获得恒力的工作原理,基于有限元分析软件ANSYS进行仿真拟合,测定弹簧片的弹性刚度系数,从而计算获得正刚度弹簧的弹性刚度系数,对加工组装后的恒力挤压机构进行压力测试。结果恒力机构的仿真结果与实验结果一致,并且在3.5 mm行程范围内实现了2%的压力恒定性。结论实验证实了挤压单元的恒力特性,为今后的假肢手接受腔分时分区控制奠定了基础。     

Raman spectroscopy for the study of porous composite alumina coating

A new acetabular cup prosthesis made of alumina and bioactive glass was studied and evaluated using nondestructive and noninvasive Raman laser spectroscopy. The prosthesis consists of an alumina socket coated with a double layer of alumina beads bonded to the prosthesis with a layer of glass. Raman spectroscopy showed that both the socket and the beads are composed of alpha-Al2O3 (corundum), while the bioactive glass (alkaline and alkaline earth alumosilicate with a small quantity of zirconium oxide) showed this to have an intermediate structure between that of vitreous silica and that of the alkaline and alkaline earth disilicate glasses. The Raman spectra of the contact surfaces between the bioactive glass and the alumina of the assembled prosthesis and of an alumina disk coated with the same glass showed the presence of new bands which may be correlated with a chemical interaction between the components of the prosthesis.     

Static and dynamic pressure prediction for prosthetic socket fitting assessment utilising an inverse problem approach

Objective

It has been recognised in a review of the developments of lower-limb prosthetic socket fitting processes that the future demands new tools to aid in socket fitting. This paper presents the results of research to design and clinically test an artificial intelligence approach, specifically inverse problem analysis, for the determination of the pressures at the limb/prosthetic socket interface during stance and ambulation.

Methods

Inverse problem analysis is based on accurately calculating the external loads or boundary conditions that can generate a known amount of strain, stresses or displacements at pre-determined locations on a structure. In this study a backpropagation artificial neural network (ANN) is designed and validated to predict the interfacial pressures at the residual limb/socket interface from strain data collected from the socket surface. The subject of this investigation was a 45-year-old male unilateral trans-tibial (below-knee) traumatic amputee who had been using a prosthesis for 22 years.

Results

When comparing the ANN predicted interfacial pressure on 16 patches within the socket with actual pressures applied to the socket there is shown to be 8.7% difference, validating the methodology. Investigation of varying axial load through the subject's prosthesis, alignment of the subject's prosthesis, and pressure at the limb/socket interface during walking demonstrates that the validated ANN is able to give an accurate full-field study of the static and dynamic interfacial pressure distribution.

Conclusions

To conclude, a methodology has been developed that enables a prosthetist to quantitatively analyse the distribution of pressures within the prosthetic socket in a clinical environment. This will aid in facilitating the “right first time” approach to socket fitting which will benefit both the patient in terms of comfort and the prosthetist, by reducing the time and associated costs of providing a high level of socket fit.     

The low er lim b prosthesis fittingfor non┐ideal stum p andfor sports prosthesis

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The Lower Limb Prosthesis Fitting for Non-ideal Stump

1.PrefaceLowerlimbprosthesisisusedbylowerlimbaxnputeetosubstitutethelostfunctionsofstandingandwalking.TheeffectofsubstitutefunctioniscloselylinkedwiththeconditionofthestUmp.AmputeeswhohaveidealstUmpcannotonlywalk,rimandjump,butparticipategames,whilethoseWhohavenon-idealstumpwillmeetlotsofdifficultiesinprosthesisfitting,thusspecialWaysshouldbetakenaccordingtodifferentconditionsofstUInp.Therefore,thispaperproposestheeffectivemethodsfornon-idealstUmPprosthesisfittingthloughthepast8.5yearsprac…     

Morphological Features of Peri-Implant Tissue after Placement of Dental Implants into the Extraction Socket

In experiments on pigs, bone regeneration was studied after implantation of implants with four cylindrical roots and support cone and laminar crest-shaped implants with shape memory effect. The implants were placed to the extraction socket (mandibular canine) and through the socket immediately after tooth extraction using osteoplastic material or without using collapan-L. The use of collapan-L accelerated regeneration of peri-implant tissue and provided stable fixation of dental construct in the bone over 3 months after surgery, which can be relevant for determining timing of prosthodontic therapy and constructional features of prosthesis.     

Biomechanical Characterisation of Bone-anchored Implant Systems for Amputation Limb Prostheses: A Systematic Review

Bone-anchored limb prostheses allow for the direct transfer of external loads from the prosthesis to the skeleton, eliminating the need for a socket and the associated problems of poor fit, discomfort, and limited range of movement. A percutaneous implant system for direct skeletal attachment of an external limb must provide a long-term, mechanically stable interface to the bone, along with an infection barrier to the external environment. In addition, the mechanical integrity of the implant system and bone must be preserved despite constant stresses induced by the limb prosthesis. Three different percutaneous implant systems for direct skeletal attachment of external limb prostheses are currently clinically available and a few others are under investigation in human subjects. These systems employ different strategies and have undergone design changes with a view to fulfilling the aforementioned requirements. This review summarises such strategies and design changes, providing an overview of the biomechanical characteristics of current percutaneous implant systems for direct skeletal attachment of amputation limb prostheses.     

A proposed model of the response of the anophthalmic socket to prosthetic eye wear and its application to the management of mucoid discharge

Mucoid discharge associated with prosthetic eye wear can be a distressing condition that affects the quality of life of people who have lost an eye. Discharge is the second highest concern of experienced prosthetic eye wearers after health of the companion eye and is prevalent in anophthalmic populations. Specific causes of mucoid discharge such as infections and environmental allergens are well understood, but non-specific causes are unknown and an evidence based protocol for managing non-specific discharge is lacking. Current management is based on prosthesis removal and cleaning, and professional re-polishing of the prosthesis. Tear protein deposits accumulate on prosthetic eyes. These deposits mediate the response of the socket to prosthetic eye wear and their influence (good and bad) is determined by differing cleaning regimes and standards of surface finish.     

Effects of liner stiffness for trans-tibial prosthesis: a finite element contact model

The socket liner plays a crucial role in redistribution of the interface stresses between the stump and the socket, so that the peak interface stress could be reduced. However, how the peak stress is affected by various liner stiffnesses is still unknown, especially when the phenomenon of the stump slide within the socket is considered. This study employed nonlinear contact finite element analyses to study the biomechanical reaction of the stump sliding with particular attention to the liner stiffness effects of the trans-tibial prosthesis. To validate the finite element outcomes, experimental measurements of the interface stresses and sliding distance were further executed. The results showed that the biomechanical response of the stump sliding are highly nonlinear. With a less stiff liner, the slide distance of the stump would increase with a larger contact area. However, this increase in the contact area would not ensure a reduction in the peak interface stress and this is due to the combined effects of the non-uniform shape of the socket and the various sliding distances generated by the different liner stiffnesses.