全膝关节置换个体化患者右转步态的骨肌多体动力学仿真

目的构建个体化患者全膝关节置换(total knee replacement,TKR)的骨肌多体力学模型,模拟患者下肢右转步态时体内膝关节的生物力学行为。方法以1位具体患者的相关数据为材料,基于骨肌动力学仿真软件Any Body及其依赖于力的运动学建模方法,建立与患者相对应的TKR下肢骨肌多体动力学模型,并对患者的右转步态进行模拟。通过逆动力学分析右转步态,同时预测患者膝关节接触力、关节运动、肌肉活性和韧带力。结果模型预测的胫骨-股骨关节内、外侧接触力的均值均方根误差分别为285、164 N,相关系数分别为0.95和0.61,预测的髌骨接触力均值最大值为250 N。模型预测的接触力和肌肉活性与患者实验测量结果基本一致。此外,模型预测的胫骨-股骨的伸展弯曲、内外旋和内外翻运动的均值分布范围分别为3°~47°、-3.4°~1.5°、0.2°~-1.5°,胫骨-股骨的前后、上下和内外侧平移的运动范围分别为2.6~9.0 mm、1.6~3.2 mm、4.2~5.2 mm。模型还预测了内、外侧旁系韧带力和后交叉韧带力,其最大值分别为190、108、108 N。结论所开发的模型能够预测人工膝关节体内生物力学行为,为后续研究膝关节假体临床失效问题提供强有力的计算平台。     

UKA 关节线安装误差对膝关节接触力学和运动学影响

目的 针对单髁膝关节置换(unicompartmental knee arthroplasty, UKA)内侧假体松动和外侧关节软骨退化问题,通过骨肌多体动力学方法研究不同生理活动中UKA关节线安装误差对膝关节接触力学和运动学的影响。方法 以内侧自然关节线为0 mm误差,分别考虑±2 mm、±4 mm、±6 mm共6种关节线安装误差情况,建立7个内侧UKA置换的骨肌多体动力学模型,对比研究步行和下蹲运动中膝关节接触力学和运动学的变化。结果 在步行步态周期70%时,相比于0 mm误差UKA假体关节线升高2 mm时内侧假体接触力增大127.3%,外侧软骨接触力减少12.0%;在UKA假体关节线降低4 mm时内侧假体接触力接近0 N,外侧软骨接触力增大10.1%;胫股关节总接触力在关节线升高和降低2 mm时分别增大19.7%和减小14.2%。在下蹲屈膝100°时,相比于0 mm误差膝关节内侧假体接触力和胫股骨关节总接触力在UKA假体关节线升高2 mm时分别增大31.6%和11.1%,在UKA假体关节线降低2 mm时分别减小24.5%和8.5%,而膝关节外侧软骨接触力变化不大。同时,在步行步态...     

人体膝关节平地行走时的动力学模拟

基于美国BRG公司的运动及动力学仿真分析软件LifeMOD,建立包括股骨、胫骨、腓骨、4条主要韧带及肌肉在内的较完整的膝关节动力学模型,并用该模型模拟了人体下肢在平地行走时膝关节的动力学行为以及前交叉韧带缺损对膝关节接触力大小的影响。通过动力学分析,得到人体在平地行走时,胫股关节之间最大的接触力值为2645N,最大韧带张力为590N,发生在内侧副韧带上;当胫股关节之间的滑动受到限制时,最大的韧带张力发生在前交叉韧带上,为560N,研究结果与文献较接近。通过动力学模拟,可以得出结论：胫股关节之间的滑动对韧带张力有较大影响;前交叉韧带缺损使得胫股关节之间的接触力变小。     

OpenSim在人体骨肌系统生物力学中的应用

斯坦福大学开发的生物力学与步态分析软件OpenSim主要用于人体肌肉骨骼系统的可视化、建模与分析,在生物力学、神经科学、人体工程、康复工程、体育科学和教育等领域得到了广泛的应用.该文从人体骨肌系统仿真分析的发展历史,基于OpenSim的运动与动力学分析、生物力学应用建模、平台算法创新与外部软件的连接和功能扩展等方面对O...     

基于膝关节三维模型的髌股关节动力学特性研究

目的构建有效的膝关节三维模型以计算髌股关节动力学参数。方法基于CT图像处理和CAD技术, 重建包括股骨下端、胫骨上端及髌骨的膝关节的骨骼三维模型,并定义髌股关节运动起重要作用的股四头肌直线模型、韧带及其它软组织的非线性弹性纤维束模型,以股四头肌肉力为输入控制变量。结果构造出一个有效的膝关节三维模型。结论该模型可以有效的计算髌股关节动力学参数。     

基于关节坐标系的肌肉骨骼间附着点坐标转换方法

目的运动状态下对人体骨肌系统进行运动学及动力学分析时,应避免对人体造成伤害。本研究通过尸体切片、CT或者MRI图像重建等方法构建静态骨肌模型,并将其应用于活体进行分析。方法采用尸体切片数据重建下肢的三维骨肌模型,并对此骨肌模型及活体下肢建立统一规则的关节坐标系,详细描述人体骨肌系统模型和活体上相关肌肉骨骼间附着点空间坐标值转换。结果对研究对象膝关节屈曲运动中股二头肌短头力臂及长度进行计算和分析。结论该方法对提高人体运动学和动力学仿真及肌肉力预测具有重要意义。     

膝关节矢状面机构模型

建立矢状面上膝关节二维机构模型，求解矢状面髌股关节求解屈膝过程中髌骨与股骨的接触点移动，髌骨倾角、髌韧带倾角变化，髌股关节功能角变化以及髌股接触力和髌韧带作用力的变化等髌股关节运动及动力学参数．依据膝关节主要组成部分的功能及相互间连接关系，以股胫关节交叉四连杆模型为基础，通过对髌股关节的几何描述及力平衡限定，并运用ADAMS软件进行分析计算，计算结果与文献实验结果吻合良好。     

基于影像学构建个体化OpenSim下肢肌骨模型的生物力学研究应用进展

由于OpenSim肌骨系统模拟平台开源性,近年来快速发展且被大量研究使用。个体化OpenSim肌骨模型可计算基础的运动学与动力学数据,揭示神经肌肉控制、肌肉力量和几何学变化及关节接触力等信息;结合影像学建模分析病理步态的神经肌肉控制及辅具的人机工效学评估等研究均表明其应用的可靠性与可行性,但存在耗时及足踝关节模拟的局限性。构建个体化病理肌骨模型,能提升临床生物力学及医学工程学研究的精准性和多样性,揭示不同病理特点,并为制定精准的诊断与康复方案、健康监测与评估状况及外部装置的工效学定制与测评提供科学依据,以及为未来该领域研究提供启示与方向。     

基于Anybody软件平台冷水刺激前后食指动力学的特性

背景：Anybody人体建模仿真系统是计算机辅助人类工效学和生物力学分析软件,并且是目前惟一可以分析完整骨骼肌肉系统的软件,利用它可以计算模型中骨骼、肌肉、关节的受力变形。 目的：实验旨在通过计算模型观察手指在冷水刺激环境下食指的灵活性。 方法：参照以往人食指运动实验结果,获得人食指弯曲的运动学参数,利用Anybody软件平台构建正常人手部握拳运动学模型,并进一步构建了包含两根外屈肌(指浅屈肌和指深屈肌)的骨骼肌肉模型,通过逆向动力学分析,考察受冷水刺激前后手部握拳运动时肌肉力和收缩功率等的变化。 结果与结论：冷水刺激后,食指各关节在屈伸过程中的平均角速度较冷水刺激前变小,指浅屈肌的肌肉力变化幅值也较冷水刺激前增大;指深屈肌的收缩功率下降明显,而指浅屈肌收缩功率变化不大。结果证实,冷水刺激会使正常人手握拳动作变慢,且正常人手的指浅屈肌对冷水刺激更敏感,进一步说明指浅屈肌在握拳动作中的重要性。     

步态周期下半月板损伤对膝关节生物力学性能的影响

文题释义：半月板撕裂：膝关节内半月型纤维软骨破裂,撕裂原因主要是由于膝半屈或全屈位下的扭转力所造成。半月板分为内侧半月板和外侧半月板,内侧半月板较大且固定,外侧半月板较小,实验主要研究外侧半月板撕裂对力学机制的影响。 动态有限元分析：将人体正常完整步态周期作为边界条件施加在膝关节半月板模型中,观察在完整步态周期下半月板以及胫骨软骨的应力变化趋势及所受应力值大小。 背景：目前国内外对膝关节半月板的生物力学分析十分广泛,但大多集中于对膝关节屈曲运动状态下的研究,针对完整步态周期下膝关节半月板生物力学的有限元分析还不完善。 目的：通过对比外侧半月板撕裂模型与健康半月板模型,了解完整步态周期下半月板损伤后的生物力学变化机制。 方法：以健康成年人膝关节CT扫描数据为基础,建立包括胫-股骨、半月板、关节软骨在内的健康膝关节有限元模型,并在健康模型基础上进一步构建膝关节外侧半月板撕裂模型,探究在完整步态周期下膝关节外侧半月板撕裂的生物力学机制,并与健康膝模型进行对比。 结果与结论：①两种模型完整步态周期内的胫骨软骨瞬时应力变化趋势一致,但半月板撕裂模型中胫骨软骨在每一个瞬时受到的应力值均大于健康半月板模型,半月板撕裂模型与健康模型中胫骨软骨所受最大应力值分别为30,20.5 MPa;②两种模型完整步态周期内的半月板瞬时应力变化趋势是一致的,但撕裂模型中完整步态周期内半月板受到的应力均大于健康模型,半月板撕裂模型与健康模型中半月板所受最大应力值分别为69.8,41.3 MPa;③在步态周期的前60%,半月板撕裂模型中的胫骨软骨最大应力分布远大于健康模型,且随着步态周期的增长,接触范围逐渐向软骨外部边缘蔓延;在步态周期的60%以后,作用在胫骨软骨上的应力较小,最大应力的分布范围也比较小;④两种模型中健康内侧半月板应力分布基本一致,而撕裂的外侧半月板最大应力分布范围较健康内侧半月板广,在裂纹周围出现了较严重应力集中现象,且随着步态周期的进行,应力集中区域逐渐向裂纹靠近半月板前角处偏移;⑤结果表明半月板是人体膝关节中重要的承重部件,从生物力学角度可以较为直观地观察到半月板损伤对人体膝关节的危害。 ORCID: 0000-0002-2155-0058(吴铮) 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     

Interpreting Musculoskeletal Models and Dynamic Simulations: Causes and Effects of Differences Between Models

With more than 29,000 OpenSim users, several musculoskeletal models with varying levels of complexity are available to study human gait. However, how different model parameters affect estimated joint and muscle function between models is not fully understood. The purpose of this study is to determine the effects of four OpenSim models (Gait2392, Lower Limb Model 2010, Full-Body OpenSim Model, and Full Body Model 2016) on gait mechanics and estimates of muscle forces and activations. Using OpenSim 3.1 and the same experimental data for all models, six young adults were scaled in each model, gait kinematics were reproduced, and static optimization estimated muscle function. Simulated measures differed between models by up to 6.5° knee range of motion, 0.012 Nm/Nm peak knee flexion moment, 0.49 peak rectus femoris activation, and 462 N peak rectus femoris force. Differences in coordinate system definitions between models altered joint kinematics, influencing joint moments. Muscle parameter and joint moment discrepancies altered muscle activations and forces. Additional model complexity yielded greater error between experimental and simulated measures; therefore, this study suggests Gait2392 is a sufficient model for studying walking in healthy young adults. Future research is needed to determine which model(s) is best for tasks with more complex motion.     

A non-invasive measurement of the knee contact force using a subject-specific musculoskeletal model to investigate osteotomy

The varus knee has been defined as a Hip-Knee-Ankle alignment of less than 180 degrees. Varus knee alignment increases the load on the medial knee and also the risk of osteoarthritis. High tibial osteotomy has been designed to modify the malalignment of varus knee. The aim of this study was to investigate the osteotomy effects on knee adduction moment (KAM) and contact forces using a musculoskeletal and subject-specific knee model. A patient with varus knee and no symptoms of any other disease or disability participated in this study. The geometry of the multibody knee model has been modified using MR images. The solutions of its finite element model have been used to determine the parameters of the multibody model. The motion data, ground reaction force and kinetic data have been applied to run the subject-specific musculoskeletal model during the stance phase of gait. After osteotomy, the adduction moment decreased, where the maximum values are comparable to other studies. The pattern of KAM did not witness any significant changes. The total and medial contact forces reduced considerably after surgery, but the lateral contact force did not significantly change. The changes in total and medial contact forces and lack of change in lateral contact force could be explained by modification of the gait pattern after surgery.     

Evaluation of a musculoskeletal model with prosthetic knee through six experimental gait trials

Knowledge of the forces acting on musculoskeletal joint tissues during movement benefits tissue engineering, artificial joint replacement, and our understanding of ligament and cartilage injury. Computational models can be used to predict these internal forces, but musculoskeletal models that simultaneously calculate muscle force and the resulting loading on joint structures are rare. This study used publicly available gait, skeletal geometry, and instrumented prosthetic knee loading data [1] to evaluate muscle driven forward dynamics simulations of walking. Inputs to the simulation were measured kinematics and outputs included muscle, ground reaction, ligament, and joint contact forces. A full body musculoskeletal model with subject specific lower extremity geometries was developed in the multibody framework. A compliant contact was defined between the prosthetic femoral component and tibia insert geometries. Ligament structures were modeled with a nonlinear force–strain relationship. The model included 45 muscles on the right lower leg. During forward dynamics simulations a feedback control scheme calculated muscle forces using the error signal between the current muscle lengths and the lengths recorded during inverse kinematics simulations. Predicted tibio-femoral contact force, ground reaction forces, and muscle forces were compared to experimental measurements for six different gait trials using three different gait types (normal, trunk sway, and medial thrust). The mean average deviation (MAD) and root mean square deviation (RMSD) over one gait cycle are reported. The muscle driven forward dynamics simulations were computationally efficient and consistently reproduced the inverse kinematics motion. The forward simulations also predicted total knee contact forces (166 N < MAD < 404 N, 212 N < RMSD < 448 N) and vertical ground reaction forces (66 N < MAD < 90 N, 97 N < RMSD < 128 N) well within 28% and 16% of experimental loads, respectively. However the simplified muscle length feedback control scheme did not realistically represent physiological motor control patterns during gait. Consequently, the simulations did not accurately predict medial/lateral tibio-femoral force distribution and muscle activation timing.     

Contributions of muscles and external forces to medial knee load reduction due to osteoarthritis braces

BackgroundBraces for medial knee osteoarthritis can reduce medial joint loads through a combination of three mechanisms: application of an external brace abduction moment, alteration of gait dynamics, and reduced activation of antagonistic muscles. Although the effect of knee bracing has been reported independently for each of these parameters, no previous study has quantified their relative contributions to reducing medial knee loads.MethodsIn this study, we used a detailed musculoskeletal model to investigate immediate changes in medial and lateral loads caused by two different knee braces: OA Assist and OA Adjuster 3 (DJO Global). Seventeen osteoarthritis subjects and eighteen healthy controls performed overground gait trials in unbraced and braced conditions.ResultsAcross all subjects, bracing reduced medial loads by 0.1 to 0.3 times bodyweight (BW), or roughly 10%, and increased lateral loads by 0.03 to 0.2 BW. Changes in gait kinematics due to bracing were subtle, and had little effect on medial and lateral joint loads. The knee adduction moment was unaltered unless the brace moment was included in its computation. Only one muscle, biceps femoris, showed a significant change in EMG with bracing, but this did not contribute to altered peak medial contact loads.ConclusionsKnee braces reduced medial tibiofemoral loads primarily by applying a direct, and substantial, abduction moment to each subject's knee. To further enhance brace effectiveness, future brace designs should seek to enhance the magnitude of this unloader moment, and possibly exploit additional kinematic or neuromuscular gait modifications.     

Limited knee extension during gait after total knee arthroplasty is related to a low Oxford Knee Score

BackgroundAfter total knee replacement (TKR) some patients report low self-perceived function, which is clinically measured using patient reported outcome measures (PROMs). However, PROMs, e.g. the Oxford Knee Score (OKS), inherently lack objective parameters of knee function. Biomechanical gait analysis is an objective and reliable measurement to quantitatively assess joint function. Therefore, the aim of this study was to explore the relationship between biomechanical gait parameters and the OKS.MethodsGait analyses were recorded in 37 patients at least one year after primary TKR and in 24 healthy controls. Parameters from this analysis were calculated for hip, knee and ankle joint angles and joint moments in the sagittal and frontal plane including initial contact, early, late stance and swing. For the patients these parameters were expressed as its difference to control values at matched walking speed. Linear regression analyses were performed between the parameters from gait analysis and the OKS, with speed as covariate.ResultsThe difference in knee extension angle at initial contact and late stance between patients and controls was significantly related to the OKS. Per one degree knee extension difference increase, the OKS reduced with 1.0 to 1.6 points. Overall, patients extended their knee less than controls. Neither ankle and hip gait parameters, nor joint moments showed a relation with OKS.ConclusionsAll patients with a submaximal score on the OKS showed limited knee extension during gait, even without a mechanical constraint in knee extension. This could be related to motor control limitations in this patient group.     

人体足地接触模型的步速适用性

目的构建骨肌多体动力学足地接触模型,研究其适用速度范围。方法采集5名测试者的步态运动数据,以骨肌多体动力学仿真软件Any Body全身模型为基础,建立足地接触模型,分析慢走、正常行走、快走和慢跑不同步态速度下的地面反作用力(ground reaction force,GRF)和地面反作用力矩(ground reaction moment,GRM),并与测力板实验测量值进行对比,分析模型预测精度,获得足地接触模型的适用范围。结果在慢走、正常走和快走(步速0. 69~1. 68 m/s)时,足地接触模型预测能力较高,GRF预测值与实验值相关性大于0. 875,GRM预测值与实验值相关性大于0. 9。结论所开发的足地接触模型同时计算GRF和GRM,可以消除步态分析中对测力板的依赖,能够应用于老年人及病理性步态等低速步态的运动学分析。     

Changes in gastrocnemii activation at mid-to-late stance markedly affects the intact and anterior cruciate ligament deficient knee biomechanics and stability in gait

IntroductionWe aimed to quantify the sensitivity in biomechanical response and stability of the intact and anterior cruciate ligament deficient (ACL-D) joints at mid-to-late stance periods of gait to the alterations in activation of gastrocnemii (Gas) muscles.MethodsA validated kinematics-driven musculoskeletal finite-element model of the lower extremity is used to compute knee joint response and stability under reported kinetics–kinematics of healthy subjects. Activation in Gas is altered under prescribed gait data at the mid-to-late stance of gait and associated changes in remaining muscle forces/contact forces/areas/ACL force and joint stability are computed in both intact and ACL-D joints.ResultsIn the intact joint, the anterior-tibial-translation (ATT) as well as ACL and joint contact forces follow variations in Gas forces. Both the stability and ATT of an ACL-D joint are restored to the near-intact levels when the activity in Gas is reduced. Knee joint instability, excessive ATT as well as larger peak articular contact stresses with a posterior shift in contact areas are estimated under greater Gas forces.ConclusionsACL-D joint is unstable with ATT > 10 mm under larger activities in Gas. Gas is an ACL-antagonist while hamstrings and soleus are ACL-agonists. The near-intact joint stability and ATT of an ACL-D joint can be restored at a lower activation in Gas; or in other words, when activation in ACL-antagonist muscles drops compared with that in ACL-agonist muscles. Results could help analyze the gait of ACL-D copers and non-copers and provide better understanding towards improved preventive, diagnostic, and treatment approaches.