基于SGGC-Net的动作捕捉系统解析行走步态的信度与效度

目的 以有标记点三维运动捕捉系统（Vicon）为参照标准,比较基于SGGC-Net的动作捕捉系统（SGGC-Net系统）和SIMI系统解析行走步态的信度和效度。方法 招募30名健康大学生,分析其在跑步机行走时的步态特征。应用Vicon系统12台红外摄像头及4台摄像机同步采集运动学数据,获取右侧参与者肩、肘、髋、膝和踝关节三维空间角度。采用组内相关系数（intra-class correlation coefficient,ICC）及其95%置信区间和测量标准误差（standard errors of measurement,SEM）评估信度;采用多重相关系数（multiple correlation coefficients,CMC）和均方根误差（root mean square error,RMSE）评估效度。结果 SGGC-Net系统解析上、下肢三维空间角度最大、最小值的ICC范围为0.798~0.990,SEM范围为0.04°~0.95°;SIMI系统的ICC范围为0.650~0.967,SEM范围为0.31°~1.24°。除髋关节最小角度和膝关节最大角度外,SGGC-Net系统解析所有角度的ICC均高于SIMI系统,且SEM均低于SIMI系统。与Vicon系统得出的上、下肢主要关节角度曲线相比,SGGC-Net系统得出的曲线CMC范围为0.945~0.996,RMSE为1.44°~4.65°;SIMI系统的CMC范围为0.815~0.986,RMSE为2.56°~9.99°。除踝关节外,SGGC-Net系统在所有角度上的CMC均大于SIMI系统,RMSE均小于SIMI系统。结论 SGGC-Net系统在大多数指标中的信度和效度优于SIMI系统,其在解析行走步态时具有较好的可重复性和准确性,可适用于无标记点情境下的动作捕捉,如运动员动作技术分析与特殊人群的临床步态解析。     

脑卒中患者运动过程中动力学特征的智能预测

目的 使用主成分分析（principal component analysis,PCA）和反向传播(back propagation,BP)神经网络预测脑卒中患者行走时患侧髋、膝、踝的关节力矩。方法 30例脑卒中患者通过8镜头Qualisys红外光点高速运动捕捉系统和Kistler三维测力台同步采集运动学和动力学数据。通过OpenSim计算脑卒中患者髋、膝、踝患侧关节力矩,采用PCA来筛选累积贡献率达到99%的初始变量,采用标准均方根误差（normalized root mean squared error,NRMSE）、均方根误差（root mean squared error,RMSE）、平均绝对百分比误差（mean absolute percentage error,MAPE）和平均绝对误差（mean absolute error,MAE）、R2作为PCA-BP模型的评价指标。使用肯德尔W系数评价计算关节力矩与预测力矩之间的一致性。结果 PCA数据显示躯干、骨盆、患侧髋、膝和踝关节在x、y、z轴（矢状、冠状、垂直轴）对患侧髋、膝、踝关节力矩具有显著影响。预测值与测量值间NRMSE为5.14%~8.86%,RMSE为0.184~0.371,MAPE为3.5%~4.0%,MAE为0.143~0.248,R2为0.998~0.999。结论 建立的PCA-BP模型可准确预测脑卒中患者行走时的髋膝踝关节力矩,显著缩短测量时间。在脑卒中患者的步态分析中本模型可代替传统的关节力矩计算,为获得脑卒中患者生物力学数据提供新途径,以及为脑卒中患者临床治疗提供有效的方法。     

髌骨沟的应用解剖

目的　为全膝关节成形术重建下肢正确力线提供解剖学基础。方法　在 40根干性股骨标本上用金属丝标记解剖轴、机械轴、髁上轴、经髁轴和髌骨沟全长 ,拍摄正位、侧位和轴位X线片 ,观测髌骨沟的弧长和弧度 ,髌骨沟与 4条基本轴线的角度。结果　髌骨沟的弧长和弧度变化幅度分别为 (2 0 .6± 1.8) (18.6～ 2 4.5 )mm和 115 .4°± 5 .6°(10 8.6°～ 118.4°) ;髌骨沟和股骨的 4条基本轴线的关系变化极大 ,变化范围在 10 .0°～ 16 .5°,髌骨沟最接近垂直干经上髁轴线。结论　在设计全膝人工关节股骨假体部分时 ,可参考髁上轴来确定髌骨沟的位置 ,使髌股关节能最大限度的匹配 ,减少术后并发症     

穿不同鞋与裸足对羽毛球蹬地动作下肢及跖趾关节运动协调特征的影响

目的探讨穿着不同鞋和裸足对羽毛球典型蹬跨步动作蹬地时腿下肢和跖趾关节运动协调的影响,为羽毛球运动的科学训练和专用鞋的选择及研发提供理论基础。方法选取优秀男子羽毛球运动员作为研究对象,穿着某品牌羽毛球成品鞋、某款羽毛球样品鞋和裸足作为不同鞋条件,并以羽毛球典型蹬跨步作为测试动作。利用Vicon运动捕捉系统和高速摄像仪同步采集下肢蹬地过程中髋、膝、踝和跖趾关节的运动学及协调特征。结果(1)在蹬地阶段,穿着两款羽毛球专项鞋时下肢各关节的运动学表现并无显著性差异,但相比裸足,两款鞋均在一定程度上增加踝、跖趾关节的角速度,并显著减低各关节角速度到达峰值的时间;(2)下肢运动协调特征方面,3种足鞋条件均表现为在相近时间内下肢髋、膝、踝和跖趾关节由近及远依次加速蹬伸。结论穿着运动鞋具备更好的蹬伸动力来源,能增加蹬伸的速度和效果,有利于提高运动表现;羽毛球蹬伸动作协调性的表现形式倾向于顺序性与同步性的合理组合,建议应针对性地加强踝、跖趾等末端关节的速度和力量训练。     

下肢不等长对步态影响的实验分析

目的采用正常人体单侧增高模拟下肢不等长,分析下肢不等长步态特征,研究下肢不等长对步态的影响,为下肢假肢穿戴者因下肢不等长引起的慢性疾病提供理论依据。方法通过单侧穿鞋增高人为制造下肢不等长,利用三维动态捕捉系统和地面反力采集设备采集受试者在正常步态和下肢不等长步态下的时空参数、地面反力和关节角度,并进行对比分析。结果下肢不等长步态与正常步态在步长、步长时间和单侧支撑期存在显著差异。下肢不等长步态左右腿足跟着地期垂直方向地面反力均大于正常步态,髋、膝、踝角度存在明显变化。结论下肢不等长是造成行走步态异常的重要原因,可能是下肢假肢穿戴者产生腿部关节疾病的原因。     

齿状突发育畸形(终末骨)一例报告

齿状突发育畸形(终末骨)少见,我们遇到一例,现报告如下:1 患者 男,31岁,因左下肢麻木9年,右下肢无力3年,加重3月入院,曾在外院诊断脊髓多发性硬化症,治疗无好转.既往无外伤病史.神经系统检查:十二对颅神经正常,四肢肌张力正常,双上肢肌力Ⅴ°双下肢肌力Ⅳ°,右下肢肌肉轻度萎缩,双下肢腱反射亢进,踝阵挛阳性,双侧Babinski征阳性,右侧Hoffmann征阳性.腰穿:脑脊液化验正常;经颅多普勒:颈内动脉及椎基动脉系统动脉血流速度正常;神经电生理检查提示中枢性脊髓损害.     

胫骨外侧髁骨折塌陷对关节轴线及接触压力的影响

目的:研究在胫骨外侧髁骨折中关节面塌陷和外侧半月板切除对膝关节轴线、接触面积及压力的影响。方法:6个新鲜尸体膝关节标本制成胫骨外侧髁劈裂骨折模型,通过使用支撑垫片制成关节面塌陷0、1、2、4和6mm。膝关节在屈膝0°,负荷500N和屈膝30°,负荷350N。通过数码相机记录关节轴线的变化;而关节内外间隙的压力和压力扩散则由F-Scan感应器记录。每个标本在保留和切除外侧半月板下进行测试。结果:随着关节面塌陷高度的增加,膝关节外翻角度、外侧间隙的平均和最大的接触压力逐渐增加,而接触面积则逐渐减少。在屈膝0°,关节面塌陷6mm时,外翻角度平均增加7.6°,平均接触压力和最大接触压力分别增加208%和97%;而接触面积则减少33%。在同一关节面塌陷高度,切除半月板平均增加38%的外翻角度和外侧间隙45%的接触压力;而接触面积则减少26%。结论:研究结果表明在治疗胫骨外髁劈裂骨折中,减少关节面的塌陷十分重要,特别是在需切除半月板的时候。     

老年人下楼梯下肢关节做功模式分析

目的 探究下楼梯行走过程中老龄化对老年人下肢关节做功模式的影响,丰富楼梯行走的防跌倒理论。 方法 采用 Vicon 红外运动捕捉系统和 Kistler 三维测力台同步采集青年人和老年人下楼梯行走的运动学和动力学数据,利用下肢关节角度、力矩、功率、做功贡献度指标对下肢关节做功模式进行量化评定。 结果 下楼梯过程中,青 年组和老年组下肢三关节角度、力矩、功率的变化趋势一致。 在优势腿的 1 个支撑相内,老年人的屈髋力矩峰值、伸膝力矩第 1 峰值、第 2 峰值、跖屈力矩第 1 峰值、膝负功率第 1 峰值、第 2 峰值、踝负功率峰值以及髋、膝、踝关节净功均显著降低(P<0. 05);伸髋力矩峰值、髋负功率峰值、踝关节做功贡献度显著增加(P<0. 05),髋、膝关节做功贡献度并未出现显著性差异(P>0. 05)。 结论 在下楼梯过程中,老年人下肢关节力学特征显著降低。 老年人采取不同于青年人的下肢关节做功模式。 老年人通过较大的伸髋姿势抵制躯干的过度前倾,同时采取踝关节做功的代偿模式,提高下楼梯行走的身体稳定性。 建议老年人在锻炼时应以增加膝、踝关节肌肉力量的项目为主,以维持下楼梯的姿势控制能力。     

高跟鞋对行走中女性躯干、下肢的力学影响

通过探讨高跟鞋对行走中女性躯干、下肢的生物力学影响,可以为设计更符合人体运动功能的高跟鞋提供理论依据.通过总结本文得出高跟鞋对女性的常见损伤有扁平足、足趾畸形、踝关节扭伤、膝关节炎、腰背酸痛;穿高跟鞋行走的步态特征是步幅小、步速慢、周期长、重心起伏大、单支撑时相缩短;其力学特征有足底受力不均匀、踝关节受力减少、膝关节内压力增大、下肢肌肉肌力变小、脊柱负荷加大等.总之长期穿高跟鞋行走对女性躯干、下肢产生许多不利影响,因此建议女性平时尽量少穿高跟鞋.     

护踝对功能性踝关节不稳患者下肢运动生物力学特征的影响

目的 探究护踝对功能性踝关节不稳(functional ankle instability,FAI)患者的保护作用,为其护踝的选择提供依据。 方法 15 名 FAI 患者随机佩戴半刚性、弹性护踝及无护踝以自选速度步行和跑步,运用红外光点运动捕捉系统和三维测力台采集其下肢运动生物力学参数。 通过 3×2 重复设计的双因素方差分析检验护踝和运动模式对下肢运动学、动力学和能量吸收的影响。 结果 护踝与运动模式对本研究中所有指标均无交互作用(P>0. 05)。不论运动模式,与无护踝相比,弹性护踝显著减少了 FAI 患者踝关节内翻角峰值、内翻角速度和踝关节能量吸收(P<0. 05),同时增加了踝关节外翻力矩( P < 0. 001);而半刚性护踝增加了踝关节内翻角峰值和内翻角速度(P<0. 05)。 此外,弹性护踝可降低着地时刻的膝关节内旋力矩和外旋力矩峰值(P<0. 05)。 结论 与无护踝相比,弹性护踝通过减小踝关节内翻角、内翻角速度和能量吸收,增大踝关节外翻力矩,继而起到预防踝关节扭伤的作用。 FAI 患者佩戴半刚性护踝后需定时关注踝关节慢性损伤风险。 整体来看,弹性护踝的防护效果可能更有效,且未引起膝关节功能补偿,可作为预防 FAI 患者踝关节扭伤的有效措施。     

Ageing effects on knee and ankle joint angles at key events and phases of the gait cycle

The objective of this research was to determine whether joint angles at critical gait events and during major energy generation/absorption phases of the gait cycle would reliably discriminate age-related degeneration during unobstructed walking. The gaits of 24 healthy adults (12 young and 12 elderly) were analysed using the PEAK Motus motion analysis system. The elderly participants showed significantly greater single (60.3% versus 62.3%, p < 0.01) and double ( p < 0.05) support times, reduced knee flexion (47.7° versus 43.0°, p < 0.05) and ankle plantarflexion (16.8° compared to 3.3°, p = 0.053) at toe off, reduced knee flexion during push-off and reduced ankle dorsiflexion (16.8° compared to 22.0°, p < 0.05) during the swing phase. The plantarflexing ankle joint motion during the stance to swing phase transition (A₂) for the young group (31.3°) was about twice ( p < 0.05) that of the elderly (16.9°). Reduced knee extension range of motion suggests that the elderly favoured a flexed-knee gait to assist in weight acceptance. Reduced dorsiflexion by the elderly in the swing phase implies greater risk of toe contact with obstacles. Overall, the results suggest that joint angle measures at critical events/phases in the gait cycle provide a useful indication of age-related degeneration in the control of lower limb trajectories during unobstructed walking.     

Error performances of a model-based biplane fluoroscopic system for tracking knee prosthesis during treadmill gait task

Roentgen stereophotogrammetry analysis technique allows an accurate measurement of knee joint prosthesis position and orientation using two X-ray images. Although this technique is used generally during static procedure, it is possible to use it with a biplane fluoroscopic system to measure the prosthesis kinematics during functional tasks (e.g., gait, squat, jump) performed in a laboratory environment. However, the performance of the system in terms of errors for the measurements and the model-based matching algorithm are not well known for dynamic tasks such as walking. The goal of this study was to estimate the static and dynamic errors of a model-based biplane fluoroscopic system for a treadmill gait task and analyze the error performance according to the speed and location of the knee joint prosthesis relative to X-ray sources. The results show a static maximum error (RMSE) of 0.13° for orientation and 0.06 mm for position for prosthesis components. The dynamic errors were different for each axis of the acquisition system and each prosthesis component. The largest dynamic error was along the vertical axis for the position (RMSE = 2.42 mm) and along the medio-lateral axis (perpendicular to movement) for the orientation (RMSE = 0.95°). As expected, the error depends on the distance between the prosthesis and the source in the acquisition system as well as the linear and angular velocity of the movement. The most accurate dynamic measure was around the centroid of the acquisition system, while kinematics measurements close to the X-rays detectors gave the worst errors.     

Gait analysis in children with cerebral palsy via inertial and magnetic sensors

3D kinematic measurements in children with cerebral palsy (CP) to assess gait deviations can only be performed in gait laboratories using optoelectronic systems. Alternatively, an inertial and magnetic measurement system (IMMS) can be applied for ambulatory motion-tracking. A protocol named Outwalk has recently been developed to measure the 3D kinematics during gait with IMMS. This study preliminary validated the application of IMMS, based on the Outwalk protocol, in gait analysis of six children with CP and one typically developing child. Reference joint kinematics were simultaneously obtained from a laboratory-based system and protocol. On average, the root mean square error (RMSE) of Outwalk/IMMS, compared to the reference, was less than 17° in the transversal plane, and less than 10° in the sagittal and frontal planes. The greatest differences were found in offsets in the knee and ankle rotation, and in the hip flexion. These offset differences were mainly caused by a different anatomical calibration in the protocols. When removing the offsets, RMSE was always less than 4°. Therefore, IMMS is suitable for gait analysis of major joint angles in a laboratory-free setting. Further studies should focus on improvement of anatomical calibrations of IMMS that can be performed in children with CP.     

Comparison of nonparametric methods for static visual field interpolation

Visual field testing with standard automated perimetry produces a sparse representation of a sensitivity map, sometimes called the hill of vision (HOV), for the retina. Interpolation or resampling of these data is important for visual display, clinical interpretation, and quantitative analysis. Our objective was to compare several popular interpolation methods in terms of their utility to visual field testing. We evaluated nine nonparametric scattered data interpolation algorithms and compared their performances in normal subjects and patients with retinal degeneration. Interpolator performance was assessed by leave-one-out cross-validation accuracy and high-density interpolated HOV surface smoothness. Radial basis function (RBF) interpolation with a linear kernel yielded the best accuracy, with an overall mean absolute error (MAE) of 2.01 dB and root-mean-square error (RMSE) of 3.20 dB that were significantly better than all other methods (p ≤ 0.003). Thin-plate spline RBF interpolation yielded the best smoothness results (p < 0.001) and scored well for accuracy with overall MAE and RMSE values of 2.08 and 3.28 dB, respectively. Natural neighbor interpolation, which may be a more readily accessible method to some practitioners, also performed well. While no interpolator will be universally optimal, these interpolators are good choices among nonparametric methods.     

Acute influence of restricted ankle dorsiflexion angle on knee joint mechanics during gait

BackgroundRestrictions in range of ankle dorsiflexion (DF) motion can persist following ankle injuries. Ankle DF is necessary during terminal stance of gait, and its restricted range may affect knee joint kinematics and kinetics. The purpose of this study was to investigate the acute influence of varied levels of restricted ankle DF on knee joint sagittal and frontal plane kinematics and kinetics during gait.MethodsThirty healthy volunteers walked with a custom-designed ankle brace that restricted ankle DF. Kinematics and kinetics were collected using a 7-camera motion analysis system and two force plates. Ankle dorsiflexion was restricted in 10-degree increments, allowing for four conditions: Free, light (LR), moderate (MR) and severe restriction (SR). Knee angles and moments were measured during terminal stance.ResultsReal peak ankle DF for Free, LR, MR, and SR were 13.7 ± 4.8°, 11.6 ± 5.0°, 7.5 ± 5.3°, and 4.2 ± 7.2°, respectively. Peak knee extension angles under the same conditions were − 6.7 ± 6.7°, − 5.4 ± 6.4°, − 2.5 ± 7.5°, and 0.6 ± 7.8°, respectively, and the peak knee varus moment was 0.48 ± 0.17 Nm/kg, 0.47 ± 0.17 Nm/kg, 0.53 ± 0.20 Nm/kg, and 0.57 ± 0.20 Nm/kg. The knee varus moment was significantly increased from MR condition with an 8-degree restriction in ankle DF.ConclusionKnee joint kinematics and kinetics in the sagittal and frontal planes were affected by reduced ankle DF during terminal stance of gait. Differences were observed with restriction in ankle DF range of approximately 8°.Level of evidencelevel III     

基于深度学习融合算法的无标记点步态分析系统

目的 以有标记点三维运动捕捉系统(MoCap)为金标准,基于双向长短时记忆(bi-lateral long short term memory, BiLSTM)递归神经网络和线性回归算法构建深度学习融合模型,减小深度传感器的系统误差,从而提高深度传感器下肢运动学分析的准确性。方法 招募10名健康男性大学生进行步态分析,应用MoCap系统和Kinect V2传感器同时采集数据。通过Cleveland Clinic及Kinect逆运动学模型分别计算下肢关节角度。以MoCap系统为目标,Kinect系统得到的角度为输入构建数据集,分别用BiLSTM算法和线性回归算法构建学习模型,得到系统误差修正后的下肢关节角度。使用留一交叉验证法评估模型的性能。采用多重相关系数(coefficient of multiple correlations, CMC)及均方根误差(root mean square error, RMSE)表示下肢关节角度波形曲线相似程度以及平均误差。结果 BiLSTM网络比线性回归算法更能够处理高度非线性的回归问题,尤其是在髋关节内收/外展、髋关节内旋/外旋和踝关节趾屈/背屈角度...     

Magnified visual feedback exacerbates positional variability in older adults due to altered modulation of the primary agonist muscle

The purpose of this study was to determine whether magnified visual feedback during position-holding contractions exacerbates the age-associated differences in motor output variability due to changes in the neural activation of the agonist muscle in the upper and lower limb. Twelve young (18–35 years) and ten older adults (65–85 years) were instructed to accurately match a target position at 5° of index finger abduction and ankle dorsiflexion while lifting 10 % of their 1 repetition maximum (1RM) load. Position was maintained at three different visual angles (0.1°, 1°, and 4°) that varied across trials. Each trial lasted 25 s and visual feedback of position was removed from 15 to 25 s. Positional error was quantified as the root mean square error (RMSE) of the subject’s performance from the target. Positional variability was quantified as the standard deviation of the position data. The neural activation of the first dorsal interosseus and tibialis anterior was measured with surface electromyography (EMG). Older adults were less accurate compared with young adults and the RMSE decreased significantly with an increase in visual gain. As expected, and independent of limb, older adults exhibited significantly greater positional variability compared with young adults that was exacerbated with magnification of visual feedback (1° and 4°). This increase in variability at the highest magnification of visual feedback was predicted by a decrease in power from 12 to 30 Hz of the agonist EMG signal. These findings demonstrate that motor control in older adults is impaired by magnified visual feedback during positional tasks.     

Validation of inertial measurement units with an optoelectronic system for whole-body motion analysis

The potential of inertial measurement units (IMUs) for ergonomics applications appears promising. However, previous IMUs validation studies have been incomplete regarding aspects of joints analysed, complexity of movements and duration of trials. The objective was to determine the technological error and biomechanical model differences between IMUs and an optoelectronic system and evaluate the effect of task complexity and duration. Whole-body kinematics from 12 participants was recorded simultaneously with a full-body Xsens system where an Optotrak cluster was fixed on every IMU. Short functional movements and long manual material handling tasks were performed and joint angles were compared between the two systems. The differences attributed to the biomechanical model showed significantly greater (P ≤ .001) RMSE than the technological error. RMSE was systematically higher (P ≤ .001) for the long complex task with a mean on all joints of 2.8° compared to 1.2° during short functional movements. Definition of local coordinate systems based on anatomical landmarks or single posture was the most influent difference between the two systems. Additionally, IMUs accuracy was affected by the complexity and duration of the tasks. Nevertheless, technological error remained under 5° RMSE during handling tasks, which shows potential to track workers during their daily labour.     

Intent Recognition in a Powered Lower Limb Prosthesis Using Time History Information

New computerized and powered lower limb prostheses are being developed that enable amputees to perform multiple locomotion modes. However, current lower limb prosthesis controllers are not capable of transitioning these devices automatically and seamlessly between locomotion modes such as level-ground walking, stairs and slopes. The focus of this study was to evaluate different intent recognition interfaces, which if configured properly, may be capable of providing more natural transitions between locomotion modes. Intent recognition can be accomplished using a multitude of different signals from mechanical sensors on the prosthesis. Since these signals are non-stationary over any given stride, and gait is cyclical, time history information may improve locomotion mode recognition. The authors propose a dynamic Bayesian network classification strategy to incorporate prior sensor information over the gait cycle with current sensor information. Six transfemoral amputees performed locomotion circuits comprising level-ground walking and ascending/descending stairs and ramps using a powered knee and ankle prosthesis. Using time history reduced steady-state misclassifications by over half (p < 0.01), when compared to strategies that did not use time history, without reducing intent recognition performance during transitions. These results suggest that including time history information across the gait cycle can enhance locomotion mode intent recognition performance.     

个性化踝关节假体的设计及三维有限元分析

目的针对当前踝关节假体失效率高、临床应用风险大的问题,提出一种个性化解剖型踝关节假体的设计。方法首先建立正常人体足踝系统的三维有限元非线性模型,对模型的有效性进行验证;设计解剖型踝关节假体,对全踝关节假体置换进行几何仿真,建立假体-足踝系统的三维有限元模型;施加步态载荷,计算分析假体的生物力学特性。结果正常踝关节系统足底最大接触应力为214.6 k Pa,足骨最大等效应力为8.96 MPa。对比文献与仿真所得足底反力与足骨应力,验证了正常足踝有限元模型的可靠性。假体植入后,仿真所得距骨钛合金假体、聚乙烯衬垫、胫骨假体等效应力峰值分别为23.88、19.24、73.01 MPa,足踝假体应力相较正常足踝应力有大幅度上升。结论有限元分析的对比结果考察了个性化踝关节假体的可行性,为进一步假体设计优化以及临床应用提供参考。