负重对行军士兵下肢步态特征的影响

目的评定负重行军对下肢步态产生的影响。方法采用随机交互设计,15名健康男性受试者进行4次步行,作训着装0、7.5、27、50kg,分别采用Vicon运动捕捉系统和AMTI测力台检测髋部、膝部和踝部运动学参数的变化。结果随着负重增加,周期性步频相对增加,步幅减小,基本上维持在恒定速度;左右髋关节屈角峰值、外旋角度峰值以及左右膝关节内收峰值受到影响较为明显,但关节运动幅度能够维持。左踝关节内翻角度峰值以及右踝关节外翻角度峰值同样受到影响;下肢左右膝、踝关节的力和力矩增加。结论在既定负荷范围内,负重增加,整体上下肢关节变化较为稳定,但下肢负荷增加,可潜在增加下肢损伤的风险。     

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...     

正走和倒走的膝关节生物力学特征比较

目的 比较正走和倒走两种不同行走模式时膝关节的生物力学特征。方法 采用三维运动捕捉系统Vicon T40和测力台AMTI OR6-7采集并比较13名健康青年男性志愿者正走和倒走时的时间、空间、运动学和动力学参数。结果 与正走相比,倒走时的步速、步频和步幅均显著减小,跨步周期和支撑相所占百分比显著增加;在矢状面上,倒走时膝关节活动度、最大屈伸力矩较正走小;在冠状面上,倒走时膝关节内翻外展活动范围也较正走小,内翻力矩峰值在支撑早期较正走小,但在支撑晚期较正走大;地面反作用力在支撑早期较正走大,但在支撑晚期较正走小。结论 倒走和正走膝关节生物力学特征差异明显。与正走相比倒走在支撑相早期能减轻膝关节内侧间室的负荷,而倒走在支撑相晚期对膝关节负荷的影响则尚须进一步研究。     

Accuracy, reliability, and validity of a spatiotemporal gait analysis system

BACKGROUND: Making evidence-based decisions in the clinical management of gait dysfunction requires the ability to measure spatiotemporal gait variables validly and reliably. This study examined the accuracy, reliability, and validity of a clinical gait analysis system that is relatively inexpensive and portable, the GaitMat II (GM). METHODS: The trustworthiness of measures taken with the GM was investigated by comparing the placement of the switches on three different GM systems. Measures taken with the GM system were compared with the same measures taken simultaneously with the Vicon motion analysis system, using a repetitive dynamic signal presented to both systems. FINDINGS: Variability was present in the placement of switches on the surfaces of different GM systems. The variability in switch placement was much less than the normal variability of most gait variables measured with the GM. Excellent agreement was found between the GM and Vicon systems for timing variables but poor agreement was found for distance variables. The mean difference between the GM and Vicon measures for distance variables would have little clinical significance in adults for distance measures such as step length or stride length. CONCLUSION: The results of these studies support the reliability and validity of the GaitMat II as a clinical gait analysis tool.     

Basic walker-assisted gait characteristics derived from forces and moments exerted on the walker's handles: results on normal subjects

This paper describes a method that passively assesses basic walker-assisted gait characteristics using only force-moment measurements from the walker's handles. The passively derived gait characteristics of 22 subjects were validated against motion capture gait analysis. The force-moment based heel initial contact detection algorithm have produced a high level of concordance with heel initial contacts detected by a human inspecting the heel marker data sets of the Vicon video capture system. The algorithm has demonstrated 97% sensitivity and 98% specificity with a narrow 95% confidence interval of +/-1% during all experiments, which included five navigational scenarios. Temporal error in detecting the instances of heel initial contacts were within 5.27+/-3.66% of the overall stride time obtained from Vicon when the subjects walked in a straight line, whereas the toe-off instance estimates were within 5.18+/-2.75% of the gait cycle. The errors in determining the duration of stride time, single support, and double support were within 5.86+/-2.49%, 5.24+/-2.29%, and 4.34+/-2.13% of the gait cycle respectively. The stride time estimated, using the method presented here, correlated well with stride time computations based on visual inspection of Vicon's data, Pearson correlation coefficient r=0.86 for straight line segments. However, absolute errors were too high to estimate the single and double support phases with acceptable accuracy. The potential application of the instrumented walker and the method presented here is longitudinal basic gait assessment that can be performed outside of the conventional gait labs.     

Simultaneous bilateral unicompartmental knee replacement improves gait parameters in patients with bilateral knee osteoarthritis

BackgroundUnicompartmental knee replacement (UKR) can provide reliable clinical and functional outcomes when performed simultaneously in both knees for treating bilateral osteoarthritis (OA). No studies to date have evaluated gait pattern after simultaneous bilateral UKR. The aim of this study was to evaluate changes in gait variables after bilateral single-stage UKR (B-UKR) and to compare them with the outcomes after unilateral UKR in two other groups of patients: one with bilateral knee OA (P-UKR) and one with the contralateral knee unaffected (H-UKR).MethodsThree-dimensional motion cohort data were prospectively collected before and six months after surgery; 37 were allocated to the B-UKR (n = 13), P-UKR (n = 12) or H-UKR (n = 12) group. Spatiotemporal variables (stride length, gait speed, gait cadence, stance phase, swing phase, and double support phase) and kinematic parameters (knee flexion and extension peak values, knee range of motion (ROM), and hip abduction peak value) were analyzed using mixed analysis of variance (ANOVA). The magnitude of effect for significant outcomes (ES) was determined using Cohen's d.ResultsPostoperative improvement in gait cadence (P < 0.01; ES = 1.20), walking speed (P < 0.05; ES = 0.58), stride length (P < 0.05; ES = 0.67), knee ROM (P < 0.05; ES = 0.89), knee flexion (P < 0.05; ES = 0.94), and hip abduction (P < 0.001; ES = 1.16) was noted for the B-UKR group, whereas only stride length improved (P < 0.05; ES = 0.48) for the H-UKR group, and no changes in any gait parameter were seen for the P-UKR group.ConclusionsPostoperative improvement in gait parameters was observed in the B-UKR patients with bilateral OA. Whenever possible, simultaneous bilateral UKR should be considered in such patients.     

Validation of joint angle measurements: comparison of a novel low-cost marker-less system with an industry standard marker-based system

Human motion tracking is widely used for the assessment of movement dysfunction in orthopaedic patients. Currently, most clinical motion analysis centres use marker-based three-dimensional (3D) systems as they are deemed to be the most accurate method. However, due to space, costs and logistics they are not available in many clinical settings. This study compared joint angles measured in functional tests using the novel low-cost Microsoft Kinect Perfect Phorm system with the established marker-based Nexus VICON system. When measuring right and left knee flexion, the average difference between the VICON and Kinect Perfect Phorm measurement was 13.2%, with a SD of 19.6. Both overestimation and underestimation of the joint angle was recorded in different participants. Although the average percentage difference during hip abduction tests was lower at ?3.9%, the range of error was far greater (SD?=?75). From this, it can be concluded that the level of accuracy presented in the new low-cost Kinect Perfect Phorm system is not yet suitable for clinical assessments. However, for general tests of performance, and for tracking cases where absolute accuracy is less critical, future versions of this software may have a place.     

Relationships between early postoperative gait biomechanical factors and patient-reported outcome measures 6 months after total knee arthroplasty

BackgroundThis study was focused on the gait parameters of the knee extensor and hip abductor muscle groups, which are believed to contribute to knee joint function improvement in early postoperative TKA. The associations between patient-reported outcome measures (PROMs) 6 months after total knee arthroplasty (TKA) and the early postoperative internal knee extension moment, knee extension negative joint power, and internal hip abduction moment while walking were investigated.MethodsTwenty-one patients who underwent primary TKA for knee osteoarthritis were included. Three weeks after TKA, gait at a comfortable speed was measured by three-dimensional motion analysis. The lower limb joint angle, internal joint moment, and joint power parameters on the operated side while standing were calculated. The PROMs 6 months after TKA were assessed using the Japanese Knee Osteoarthritis Measure (JKOM). The relationship between each gait biomechanical parameter and the JKOM was determined.ResultsThe maximum internal knee extension moment and maximum knee extension negative joint power during the early stance showed moderate negative correlations with the JKOM scores. The maximum internal hip abduction moment was not correlated with the JKOM scores. The maximum internal hip extension moment during the early stance and internal hip flexion moment during the late stance showed moderate negative correlations with the total JKOM scores.ConclusionThe early postoperative internal knee extension moment, maximum knee extension negative joint power, and internal hip extension and flexion moment are associated with patient PROMs 6 months after TKA.     

Validity of the total body centre of gravity during gait using a markerless motion capture system

Purpose: The purpose of this study was to examine the validity of total body centre of gravity (COG) measurement during gait with markerless motion capture system (MLS) on the basis of values acquired with a marker-based motion capture system (MBS).

Materials and methods: Thirty young healthy subjects walked on a flat surface as coordinate data from their bodies were acquired using the Kinect v2 (as a MLS) and Vicon systems (as a MBS). COG was calculated using coordinate data of the total body. Comparisons of COG ensemble curves in the mediolateral and vertical directions were performed between MLS and MBS throughout the gait cycle. The relative consistency between these systems was assessed using Pearson correlation coefficients.

Results: The COG trajectory made by using MLS data followed the trend of the COG trajectory with MBS in the mediolateral direction. In the vertical direction, however, the COG trajectories did not match between two systems. High correlation coefficients (r >?0.79) were observed from 30% to 80% of the gait cycle. The greatest difference of COG between MLS and MBS in the mediolateral direction was 1.1?mm. Differences in the vertical direction appeared to be proportional to the distance between the participant and the Kinect v2 sensor.

Conclusion: In the mediolateral direction, COG calculated with MLS data during gait was validated with COG calculated on the basis of a MBS. Further correction of systematic error is necessary to improve the validity of COG calculations in the vertical direction.     

Development and validation of a low-cost,portable and wireless gait assessment tool

BackgroundPerforming gait analysis in a clinical setting can often be challenging due to time, cost and the availability of sophisticated three-dimensional (3D) gait analysis systems. This study has developed and tested a portable wireless gait assessment tool (wi-GAT) to address these challenges.AimTo investigate the concurrent validity of the wi-GAT in measuring spatio-temporal gait parameters such as stride length, stride duration, cadence, double support time (DST), stance and swing time compared to a 3D Vicon motion analysis system.MethodsTen healthy volunteers participated in the study (age range 23–30 years). Spatio-temporal gait parameters were recorded simultaneously by the Vicon and the wi-GAT systems as each subject walked at their self-selected speed.ResultsThe stride length and duration, cadence, stance duration and walking speed recorded using the wi-GAT showed strong agreement with those same parameters recorded by the Vicon (ICC of 0.94–0.996). A difference between the systems in registering “toe off” resulted in less agreement (ICC of 0.299–0.847) in gait parameters such as %stance and %swing and DST.Discussion and conclusionThe study demonstrated good concurrent validity for the wi-GAT system. The wi-GAT has the potential to be a useful assessment tool for clinicians.     

Adaptive control for backward quadrupedal walking. I. Posture and hindlimb kinematics

1. To gain new perspectives on the neural control of different forms of quadruped locomotion, we studied adaptations in posture and hindlimb kinematics for backward (BWD) walking in normal cats. Data from four animals were obtained from high-speed (100 fr/s) ciné film of BWD treadmill walking over a range of slow walking speeds (0.3-0.6 m/s) and forward (FWD) treadmill walking at 0.6 m/s. 2. Postural adaptations during BWD walking included flexion of the lumbar spine, compared to a relatively straight spine during FWD walking. The usual paw-contact sequence for FWD walking [right hindlimb (RH), right forelimb (RF), left hindlimb (LH), left forelimb (LF)] was typically reversed for BWD walking (RH, LF, LH, RF). The hindlimbs alternated consistently with a phase difference averaging 0.5 for both forms of walking, but the phasing of the forelimbs was variable during BWD walking. 3. As BWD walking speed increased from 0.3 to 0.6 m/s, average hindlimb cycle period decreased 21%, stance-phase duration decreased 29%, and stride length increased 38%. Compared to FWD walking at 0.6 m/s, stride length was 30% shorter, whereas cycle period and stance-phase duration were 17% shorter for BWD walking. For both directions, stance occupied 64 +/- 4% (mean +/- SD) of the step cycle. 4. During swing for both forms of walking, the hip, knee, and ankle joints had flexion (F) and extension (E1) phases; however, the F-E1 reversals occurred earlier at the hip and later at the knee for BWD than for FWD walking. At the ankle joint, the ranges of motion during the F and E1 phases were similar for both directions. During BWD walking, however, the knee flexed more and extended less, whereas the hip flexed less and extended more. Thus horizontal displacement of the limb resulted primarily from hip extension and knee flexion during BWD swing, but hip flexion and knee extension during FWD swing. 5. At the knee and ankle joints, there were yield (E2) and extension (E3) phases during stance for both forms of walking; however, yields at the knee and ankle joints were reduced during BWD walking. At the hip, angular motion was unidirectional, as the hip flexed during BWD stance but extended during FWD stance. Knee extension was the prime contributor to horizontal displacement of the body during BWD stance, but hip extension was the prime contributor to horizontal displacement during FWD stance. 6. Our kinematic data revealed two discriminators between BWD and FWD walking.(ABSTRACT TRUNCATED AT 400 WORDS)     

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。     

腰椎间盘突出症患者坐立时的运动学特征分析

目的 研究腰椎间盘突出症(lumbar disc herniation, LDH)患者在坐-立-坐任务中腰部和臀部的运动学与关节协调性变化。方法 应用Vicon三维运动捕捉系统采集20例健康对照与20例LDH受试者的运动学数据,通过统计参数映射(statistical parametric mapping, SPM)比较两组在坐立任务中腰椎与髋关节的运动模式差异。结果 在坐立任务中,LDH受试者腰椎屈伸活动度与髋关节外展角度明显受限,髋关节屈曲角度增加;SPM分析显示,两组在从坐到立的起始阶段(10%～13%),腰椎屈曲角度存在统计学差异,LDH受试者屈曲角度明显减少,而2%～14%阶段LDH受试者髋关节屈曲角度明显增加;在从立到坐阶段(65%～68%),LDH受试者则表现为髋关节外展角度增加。结论 LDH受试者在坐立过程中腰椎屈曲及髋关节外展功能受限,需代偿以髋关节屈曲活动增加来完成功能任务。在临床评估中,应重点关注脊柱与臀部的运动功能改变。     

女性穿着运动文胸与未着文胸状态下步态特征的差异性

目的比较女性穿着运动文胸和未着文胸行走时步态特征和步行稳定性的差异,为运动文胸的设计和评价提供依据。方法使用Qualisys红外光点运动捕捉系统采集12名C罩杯乳房大小女性分别穿着运动文胸及未着文胸状态下在跑步机上行走(6 km/h)的运动学参数。结果相比未着文胸状态,穿着运动文胸时上躯干角最大值及最小值显著减小,躯干屈曲角和躯干扭转角的幅度较小;10个步态周期的髋关节屈曲角幅度的标准差显著小于裸胸状态,乳房不同支撑状态对步频无显著影响。结论不同乳房支撑状态显著影响上躯干角度、躯干扭转角与躯干屈曲角。裸胸状态行走时躯干运动幅度增大,行走稳定性下降。不同乳房支撑状态下行走步频存在个体差异。     

胫骨高位双平面上行截骨与下行截骨治疗内翻型膝关节骨性关节炎效果及步态分析

目的 探讨胫骨高位双平面上行截骨与下行截骨治疗内翻型膝关节骨性关节炎的效果及步态分析.方法 遴选出2017年1月至2019年6月因内翻型膝关节骨性关节炎住院患者32例,按手术方式分为胫骨高位双平面上行截骨组和下行截骨组,以观察两组患者的膝关节HSS评分、VAS评分、胫股角(FTA)、胫骨后倾角、Insall-Salva...     

Development and validation of a user-friendly data logger (SUDALS) for use with flexible electrogoniometers to measure joint movement in clinical trials

Objective: Our aim was to develop and validate a user-friendly data logger system (SUDALS) for use with flexible electrogoniometry.

Methods: Data pertaining to flexion/extension of the knee from 10 normal subjects were collected during a range of activities of daily living (ADL) such as walking, ascending and descending stairs, getting in and out of a chair and deep squatting. The accuracy, reliability and reproducibility of the data from SUDALS were verified by comparing against the data simultaneously collected from the Vicon system.

Results: The results of these studies indicate that the SUDALS together with flexible electrogoniometers is able to produce stable, precise, accurate and repeatable knee flexion/extension angles with little variation existing between the data produced by the SUDALS, the Vicon system and that reported in the literature.

Conclusion: The SUDALS together with flexible electrogoniometers is a useful clinical tool, capable of recording knee flexion/extension angles accurately during ADL.     

不同速度下正常老年人下肢关节的角度参数

背景：目前国内主要采用步态分析仪测量患者步行时的关节角度,但是在每一个康复治疗时期进行这些测量非常耗费时间。利用Lokomat步态康复机器人则可以在患者训练过程中对患者的关节角度、肌力等参数进行实时记录,省时省力。 目的：采用步态康复机器人Lokomat测定正常老年人不同速度下的下肢关节角度参数。 方法：选取健康老年人30名,男15名,女15名,年龄60~64(62.40±1.58)岁。利用步态康复机器人评估工具,在减重40%,引导力60%,速度1.6,1.8,2.0 km/h状态下对正常老年人的下肢关节角度参数进行记录。 结果与结论：老年人关节角度参数动态指标测试结果显示,在速度1.6 km/h状态下左髋关节最大伸展角度,在速度2.0 km/h状态下左、右髋关节最大屈曲角度,男女组间差异有显著性意义(P < 0.05)。老年人不同速度下髋膝关节角度测试结果显示,老年人左右膝关节最大伸展角度在步行速度1.6 km/h与1.8 km/h,1.6 km/h与2.0 km/h,1.8 km/h与2.0 km/h相比差异有显著性意义(P < 0.05)。结果可见不同速度下髋关节最大屈曲角度男性大于女性,治疗师在进行Lokomat步态康复训练时应根据患者的性别差异,调整髋膝关节角度和训练模式。随着步行速度的增加老年人髋膝关节屈曲角度增加,伸展角度减小,治疗师应根据步速的增减适当调节髋膝关节活动度,增强患者腿部运动与机器人外骨骼式机械腿的配合,提高患者的训练效果。     

人体背部负重对于步态特征的影响及相应补偿策略的实验研究

人体背部负重量大小对步态特征的影响及相应补偿策略的研究对于自主式两足步行机器人的设计和平衡控制以及军人体能训练均有重要意义。从实验的角度对受试者分别背部负重6kg、12kg和25kg时的步态特征和补偿策略进行了研究。结果表明：人体背部负重后会引起步态特征的明显变化，这种差异主要表现在髋关节、膝关节以及上躯干的摆动角位移变化。负重后，人体的平均步速明显降低，但其步长的变化并不明显。人体对于负重的响应特征与受试者的肌肉强度是密切相关的。为有效补偿背部负重所产生的影响，人体利用多关节协调运动来进行补偿。但各个关节的贡献不同，其补偿主要由髋关节、膝关节以及上躯干的摆动来完成，踝关节的贡献相对较小。背部负重后总质心向前的调整主要是由上躯干的向前倾斜来实现。负重量越大，上躯干向前倾斜的平均角位移越大。为减少负重后的冲击对关节的损伤，脚跟触地时，可利用髋关节和膝关节的弯曲刚度来吸收冲击。     

A Wearable Magnet-Based System to Assess Activity and Joint Flexion in Humans and Large Animals

Functional outcomes, such as joint flexion and gait, are important indicators of efficacy in musculoskeletal research. Current technologies that objectively assess these parameters, including visual tracking systems and force plates, are challenging to deploy in long-term translational and clinical studies. To that end, we developed a wearable device that measures both physical activity and joint flexion using a single integrated sensor and magnet system, and hypothesized that it could evaluate post-operative functional recovery in an unsupervised setting. To demonstrate the feasibility of measuring joint flexion, we first compared knee motion from the wearable device to that acquired from a motion capture system to confirm that knee flexion measurements during normal human gait, predicted via changes in magnetic field strength, closely correlated with data acquired by motion capture. Using this system, we then monitored a porcine cohort after bilateral stifle arthrotomy to investigate longitudinal changes in physical activity and joint flexion. We found that unsupervised activity declined immediately after surgery, with a return to pre-operative activity occurring over a period of 2 weeks. By providing objective, individualized data on locomotion and joint function, this magnet-based system will facilitate the in vivo assessment of novel therapeutics in translational orthopaedic research.     

A Markerless Motion Capture System to Study Musculoskeletal Biomechanics: Visual Hull and Simulated Annealing Approach

Human motion capture is frequently used to study musculoskeletal biomechanics and clinical problems, as well as to provide realistic animation for the entertainment industry. The most popular technique for human motion capture uses markers placed on the skin, despite some important drawbacks including the impediment to the motion by the presence of skin markers and relative movement between the skin where the markers are placed and the underlying bone. The latter makes it difficult to estimate the motion of the underlying bone, which is the variable of interest for biomechanical and clinical applications. A model-based markerless motion capture system is presented in this study, which does not require the placement of any markers on the subject's body. The described method is based on visual hull reconstruction and an a priori model of the subject. A custom version of adapted fast simulated annealing has been developed to match the model to the visual hull. The tracking capability and a quantitative validation of the method were evaluated in a virtual environment for a complete gait cycle. The obtained mean errors, for an entire gait cycle, for knee and hip flexion are respectively 1.5° (±3.9°) and 2.0° (±3.0°), while for knee and hip adduction they are respectively 2.0° (±2.3°) and 1.1° (±1.7°). Results for the ankle and shoulder joints are also presented. Experimental results captured in a gait laboratory with a real subject are also shown to demonstrate the effectiveness and potential of the presented method in a clinical environment.