Effect of medial foot loading self-practice on lower limb kinematics in young individuals with asymptomatic varus knee alignment

BackgroundVarus alignment of the knee is a risk factor for developing knee osteoarthritis. Recently, voluntary shifting the plantar pressure distribution medially (medial foot loading) during gait has been found to reduce knee adduction angle during stance, which may lower the joint load. However, it is not yet known whether such effect would persist after long-term self-practice. This study aimed to determine whether medial foot loading can be an effective self-care protocol for reducing the knee adduction angle.MethodsEight subjects with asymptomatic varus knee alignment were trained on medial foot loading once in a laboratory, then carried out as self-practice for 8 weeks outside the laboratory. Spatiotemporal gait parameters and lower limb joint kinematics data were collected during natural walking prior to the training (baseline walking), during the practice session immediately after the initial training (trained walking), and during natural walking after the self-practice period (post-practice walking).ResultsParticipants walked significantly faster after the self-practice period with longer step length compared with the baseline. The knee adduction angle at initial contact, maximum angle during stance, and mean angle during a gait cycle were significantly decreased during both the trained and post-practice walking compared with baseline. The 8-week self-practice caused larger decrements in the three angles than the single training, but no significant differences were found between the two conditions.ConclusionsSelf-practice of medial foot loading walking could be an effective gait strategy to reduce the knee adduction angle. The effect could be sustained for individuals with asymptomatic varus knee alignment.     

Intersegmental coordination during human locomotion: does planar covariation of elevation angles reflect central constraints?

To study intersegmental coordination in humans performing different locomotor tasks (backward, normal, fast walking, and running), we analyzed the spatiotemporal patterns of both elevation and joint angles bilaterally in the sagittal plane. In particular, we determined the origins of the planar covariation of foot, shank, and thigh elevation angles. This planar constraint is observable in the three-dimensional space defined by these three angles and corresponds to the plane described by the three time-varying elevation angle variables over each step cycle. Previous studies showed that this relation between elevation angles constrains lower limb coordination in various experimental situations. We demonstrate here that this planar covariation mainly arises from the strong correlation between foot and shank elevation angles, with thigh angle independently contributing to the pattern of intersegmental covariation. We conclude that the planar covariation of elevation angles does not reflect central constraints, as previously suggested. An alternative approach for analyzing the patterns of coordination of both elevation and joint (hip, knee, and ankle) angles is used, based on temporal cross-correlation and phase relationships between pairs of kinematic variables. We describe the changes in the pattern of intersegmental coordination that are associated with the changes of locomotor modes and locomotor speeds. We provide some evidence for a distinct control of thigh motion and discuss the respective contributions of passive mechanical factors and of active (arising from neural control) factors to the formation and the regulation of the locomotor pattern throughout the gait cycle.     

Asymptomatic Genu Recurvatum reshapes lower limb sagittal joint and elevation angles during gait at different speeds

BackgroundKinematic characteristics of walking with an asymptomatic genu recurvatum are currently unknown. The objective of this study is to characterize the lower limb sagittal joint and elevation angles during walking in participants with asymptomatic genu recurvatum and compare it with control participants without knee deformation at different speeds.MethodsThe spatio-temporal parameters and kinematics of the lower limb were recorded using an optoelectronic motion capture system in 26 participants (n = 13 with genu recurvatum and n = 13 controls). The participants walked on an instrumented treadmill during five minutes at three different speeds: slow, medium and fast.ResultsParticipants with genu recurvatum showed several significant differences with controls: a narrower step width, a greater maximum hip joint extension angle, a greater knee joint extension angle at mid stance, a lower maximum knee joint flexion angle during the swing phase, and a greater ankle joint extension angle at the end of the gait cycle. Participants with genu recurvatum had a greater minimum thigh elevation angle, a greater maximum foot elevation angle, and a change in the orientation of the covariance plane. Walking speed had a significant effect on nearly all lower limb joint and elevation angles, and covariance plane parameters.ConclusionOur findings show that genu recurvatum reshapes lower limb sagittal joint and elevation angles during walking at different speeds but preserves the covariation of elevation angles along a plane during both stance and swing phases and the rotation of this plane with increasing speed.     

佩带膝外翻支具膝骨关节炎患者膝关节的生物力学变化

背景：佩带膝关节外翻矫形器已被证明是一种可以有效减轻内侧间室膝骨关节炎患者疼痛的方法,但是佩带矫形器后的膝关节所产生的运动学以及动力学变化至今尚不明确。 目的：观察内侧间室膝骨关节炎患者佩带膝关节矫形器前后的膝关节运动学以及动力学参数变化,便于为将来设计新型膝关节矫形器提供依据。 方法：纳入20例内侧间室膝骨关节炎患者,分别通过三维步态分析系统和测力板对其在佩带膝外翻矫形器及不佩带膝外翻矫形器两种情况步行中的运动学及动力学参数进行采集,并进行对比。 结果与结论：相比未佩带膝关节外翻支具,佩带膝关节外翻支具后患者在步行过程中膝关节内收力矩明显减小,与此同时膝关节内翻角度明显减小,外翻角度明显增加(P均< 0.05),膝关节在步行过程中的最大屈曲角度以及时间空间参数差异无显著性意义。提示膝关节外翻矫形器可有效地通过增加内侧间室膝骨关节炎患者膝关节在步行过程中的外翻角度减小内翻角度从而降低膝内侧间室所承受的压力,与此同时纠正膝关节非正常对线。     

Lower limb kinematics during treadmill walking after space flight: implications for gaze stabilization

We examined the lower limb joint kinematics observed during pre- and postflight treadmill walking performed by seven subjects from three Space Shuttle flights flown between March 1992 and February 1994. Basic temporal characteristics of the gait patterns, such as stride time and duty cycle, showed no significant changes after flight. Evaluation of phaseplane variability across the gait cycle suggests that postflight treadmill walking is more variable than preflight, but the response throughout the course of a cycle is joint dependent and, furthermore, the changes are subject dependent. However, analysis of the phaseplane variability at the specific locomotor events of heel strike and toe off indicated statistically significant postflight increases in knee variability at the moment of heel strike and significantly higher postflight hip joint variability at the moment of toe off. Nevertheless, the observation of component-specific variability was not sufficient to cause a change in the overall lower limb joint system stability, since there was no significant change in an index used to evaluate this at both toe off and heel strike. The implications of the observed lower limb kinematics for head and gaze control during locomotion are discussed in light of a hypothesized change in the energy attenuation capacity of the musculoskeletal system in adapting to weightlessness.     

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...     

How accurate are lockable orthotic knee braces? An objective gait analysis study

There has been an increasing use of orthotic knee braces in the management of knee injuries but, to our knowledge, there is no gait analysis study assessing the accuracy of these braces. Eight healthy male subjects were studied to determine the accuracy of immobilisation or splintage provided by a lockable orthotic knee brace using gait analysis. Six types of immobilisation were studied: locked at 0, 10, 20, 30° and unlocked in an orthotic knee brace, and without a brace. The knee flexion angles measured using the kinematic instruments at 0 and 10° were significantly greater than those set at the knee brace. The knee flexion angle measured using the unlocked knee brace was significantly greater than that measured in the absence of a brace. This study highlights inaccuracies in a knee brace at low knee flexion angles. The higher actual angles alter the biomechanics of the knee joint and result in greater forces across the knee joint and especially the extensor mechanism.     

不同硬度鞋底对人体步行下肢运动学的分析

目的通过对穿着不同硬度鞋底的受试者开展步行时的运动学分析,评价不同硬度鞋底对人体下肢步行运动学参数的影响。方法受试者穿3种不同硬度鞋底的鞋,在跑台上以6 km/h的速度行走,利用Vicon红外摄像系统进行动作捕捉,以采集行走过程中脚后跟高度、脚尖高度、膝角度、踝角度等运动学参数,并分析实验结果。结果穿软底鞋的步态周期比其他鞋的步态周期增加,小腿前摆角度最小;穿中等硬底鞋大腿前摆角度最小、后摆角度最大;穿硬底鞋的大腿前摆角度最大、后摆角度最小;摆动期时间相对稳定。结论软底鞋更适合短时间慢速行走,中等硬底鞋对人体长时间步行的下肢运动学影响最小,硬底鞋适合短时间快速行走。     

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。     

Errors in using fixed flexion facet centers to determine tibiofemoral kinematics increase fourfold for multi-radius femoral component designs with early versus late decreases in the radius of curvature

BackgroundOne method to determine tibiofemoral joint kinematics following total knee arthroplasty (TKA) is to quantify movement of the anterior-posterior (AP) position of the flexion facet center (FFC) on each femoral condyle relative to the tibia during knee flexion. The primary objective was to determine how closely AP positions of fixed FFCs approximate AP positions of variable FFCs of multi-radius femoral component designs with early versus late initial transition angles (i.e. earliest flexion angle where the radius of curvature decreases markedly).MethodsVariable FFCs were determined for each femoral condyle as centers of best-fit circles to 20° segments of the sagittal profile from 0° to 120° of flexion in 15° increments. The fixed FFC of each condyle was the center of the best-fit circle from 0° to 120° of flexion. Errors in AP positions were differences between AP positions of fixed FFCs and variable FFCs.ResultsFor profiles with a late initial transition angle of 120° of flexion, the root mean square error (RMSE) was limited to 0.7 mm. For profiles with an early initial transition angle of 60° of flexion, the RMSE was 2.7 mm, nearly a fourfold increase.ConclusionsTo determine whether fixed FFCs can be used to indicate AP positions of femoral condyles with minimal RMSE < 1 mm, the initial transition angle should be found as an important first step. Condylar AP positions for designs with an early initial transition angle should not be approximated by AP positions of fixed FFCs when determining tibiofemoral kinematics.     

The effects of rocker sole and SACH heel on kinematics in gait

The rocker sole and solid-ankle cushion-heel (SACH) heels are the most commonly prescribed external shoe modification. Only a limited number of scientific evidence exists to support these interventions in clinical practice. The objective of this study was to determine the effects of rocker soles and SACH heels on kinematics during gait. In this study, we investigated the gait parameters during level walking, stair climbing and stair descending in healthy volunteers and assessed the effects of the modified shoes on the motion of the forefoot and hindfoot compared with the traditional shoes. Eleven normal subjects participated in this study. A six-camera motion analysis system was used to capture motion trajectories. The three-dimensional (3D) coordinates of the markers were used to calculate the angles of flexion-extension, valgus-varus, and internal-external rotation at the hindfoot and forefoot joints in a gait cycle by the custom software for foot kinematic analysis. The results showed that the rocker soles offer several advantages from the viewpoint of gait kinematics. The forefoot joint excursion in sagittal plane while wearing rocker shoes was significantly less than that while wearing traditional shoes during level walking, stair climbing and stair descending. It means that they could mimic the action of the forefoot joint, aid in roll off, and simulate forefoot dorsiflexion. Since the bony structures mechanically link the forefoot joint and hindfoot joint to a triplanar axis of motion, they could be used whenever there is minimal or no motion at the forefoot joint or hindfoot joint, because of, for example, fusion, fracture, cast immobilization, orthosis design, pain, or arthritis.     

Femoral anatomical frame: assessment of various definitions

The reliability of the estimate of joint kinematic variables and the relevant functional interpretation are affected by the uncertainty with which bony anatomical landmarks and underlying bony segment anatomical frames are determined. When a stereo-photogrammetric system is used for in vivo studies, minimising and compensating for this uncertainty is crucial. This paper deals with the propagation of the errors associated with the location of both internal and palpable femoral anatomical landmarks to the estimation of the orientation of the femoral anatomical frame and to the knee joint angles during movement. Given eight anatomical landmarks, and the precision with which they can be identified experimentally, 12 different rules were defined for the construction of the anatomical frame and submitted to comparative assessment. Results showed that using more than three landmarks allows for more repeatable anatomical frame orientation and knee joint kinematics estimation. Novel rules are proposed that use optimization algorithms. On the average, the femoral frame orientation dispersion had a standard deviation of 2, 2.5 and 1.5 degrees for the frontal, transverse, and sagittal plane, respectively. However, a proper choice of the relevant construction rule allowed for a reduction of these inaccuracies in selected planes to 1 degrees rms. The dispersion of the knee adduction-abduction and internal-external rotation angles could also be limited to 1 degrees rms irrespective of the flexion angle value.     

Knee joint dysfunctions that influence gait in cerebrovascular injury

INTRODUCTION: There is still no consensus among different specialists on the subject of kinematic variation during the hemiparetic gait, including the main changes that take place during the gait cycle and whether the gait velocity changes the patterns of joint mobility. One of the most frequently discussed joints is the knee. OBJECTIVES: This study aims to evaluate the variables found in the angular kinematics of knee joint, and to describe the alterations found in the hemiparetic gait resulting from cerebrovascular injury. METHODS: This study included 66 adult patients of both genders with a diagnosis of either right or left hemiparesis resulting from ischemic cerebrovascular injury. All the participants underwent three-dimensional gait evaluation, an the angular kinematics of the joint knee were selected for analysis. RESULTS: The results were distributed into four groups formed based on the median of the gait speed and the side of hemiparesis. CONCLUSIONS: The relevant clinical characteristics included the important mechanisms of loading response in the stance, knee hyperextension in single stance, and reduction of the peak flexion and movement amplitude of the knee in the swing phase. These mechanisms should be taken into account when choosing the best treatment. We believe that the findings presented here may aid in preventing the occurrence of the problems found, and also in identifying the origin of these problems.     

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 degrees versus 43.0 degrees , p < 0.05) and ankle plantarflexion (16.8 degrees compared to 3.3 degrees , p = 0.053) at toe off, reduced knee flexion during push-off and reduced ankle dorsiflexion (16.8 degrees compared to 22.0 degrees , 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 degrees ) was about twice ( p < 0.05) that of the elderly (16.9 degrees ). 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.     

Quantitative video-based gait pattern analysis for hemiparkinsonian rats

Gait disturbances are common in the rat model of Parkinson's disease (PD) by administrating 6-hydroxydopamine. However, few studies have simultaneously assessed spatiotemporal gait indices and the kinematic information of PD rats during overground locomotion. This study utilized a simple, accurate, and reproducible method for quantifying the spatiotemporal and kinematic changes of gait patterns in hemiparkinsonian rats. A transparent walkway with a tilted mirror was set to capture underview footprints and lateral joint ankle images using a high-speed and high-resolution digital camera. The footprint images were semi-automatically processed with a threshold setting to identify the boundaries of soles and the critical points of each hindlimb for deriving the spatiotemporal and kinematic indices of gait. Following PD lesion, asymmetrical gait patterns including a significant decrease in the step/stride length and increases in the base of support and ankle joint angle were found. The increased footprint length, toe spread, and intermediary toe spread were found, indicating a compensatory gait pattern for impaired locomotor function. The temporal indices showed a significant decrease in the walking speed with increased durations of the stance/swing phase and double support time, which was more evident in the affected hindlimb. Furthermore, the ankle kinematic data showed that the joint angle decreased at the toe contact stage. We conclude that the proposed gait analysis method can be used to precisely detect locomotor function changes in PD rats, which is useful for objective assessments of investigating novel treatments for PD animal model.     

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...     

Predictive Simulations of Neuromuscular Coordination and Joint-Contact Loading in Human Gait

We implemented direct collocation on a full-body neuromusculoskeletal model to calculate muscle forces, ground reaction forces and knee contact loading simultaneously for one cycle of human gait. A data-tracking collocation problem was solved for walking at the normal speed to establish the practicality of incorporating a 3D model of articular contact and a model of foot–ground interaction explicitly in a dynamic optimization simulation. The data-tracking solution then was used as an initial guess to solve predictive collocation problems, where novel patterns of movement were generated for walking at slow and fast speeds, independent of experimental data. The data-tracking solutions accurately reproduced joint motion, ground forces and knee contact loads measured for two total knee arthroplasty patients walking at their preferred speeds. RMS errors in joint kinematics were?<?2.0° for rotations and?<?0.3 cm for translations while errors in the model-computed ground-reaction and knee-contact forces were?<?0.07 BW and?<?0.4 BW, respectively. The predictive solutions were also consistent with joint kinematics, ground forces, knee contact loads and muscle activation patterns measured for slow and fast walking. The results demonstrate the feasibility of performing computationally-efficient, predictive, dynamic optimization simulations of movement using full-body, muscle-actuated models with realistic representations of joint function.     

臀肌挛缩症患者三维步态特征分析

目的：探讨臀肌挛缩症患者步态的功能量化指标为该疾病的诊断提供参考与依据。方法：2011年8月-2011年11月,选取臀肌挛缩症患者16例作为研究组,同期选取健康自愿者16例作为对照组,应用三维步态系统对两组进行三维步态对比分析。结果：①步态周期时间参数：研究组在常速、快速行走时步态周期较对照组明显延长（P〈0．01）,步幅、步速较对照组均明显减小（P〈0．01）。②下肢关节角度特征：与对照组比较,研究组在常速、快速行走时髋关节摆动期最大屈曲角度及研究组快速行走时髋关节屈伸角度变化范围均减小（P〈0．05）;研究组常速、快速行走时膝关节冠状面角度变化范围均增大（P〈0．05）,而膝关节支撑相最大屈曲角度和膝关节屈伸角度范围均减小（P〈0．01）;研究组常速行走时重心左、右位移增大（P〈0．05）,快速行走时重心上、下位移减小（P〈0．05）。结论：应用三维步态分析系统对臀肌挛缩症患者进行功能量化评价,可以更为准确地观察臀肌挛缩症患者步态的生物力学变化,为患者的诊断提供了参考和依据。     

Generation of physiological parameter sets for hip joint motions and loads during daily life activities for application in wear simulators of the artificial hip joint

At present, wear investigations of total hip replacements are performed in accordance with the ISO standard 14242, which is based on simplified kinematic and force data of the gait cycle. The aim of this analytical study was to generate parameter sets of daily life activities in order to replicate more realistic joint load situations in wear testing.Hence, published in vivo motion and force data of daily life activities were evaluated and adjusted using analytical techniques. The created kinematically and dynamically consistent parameter sets comprised time trajectories of three Cardan angles to describe the motion of the femur with respect to the pelvis and time trajectories of three force components, representing the hip joint contact force. The parameter sets include the activities of walking, knee bending, stair climbing and a combined load case of sitting down and standing up. Additionally, a motion sequence following the frequency of daily life activities was presented. Differences of the evaluated angular motions and joint contact forces in comparison to the ISO standard 14242-1 were pointed out. The results of this study offer the possibility to extend the kinematics and dynamics of the ISO standard test protocol and to support the loading conditions of hip wear simulators with a comprehensive set of motions and loads close to reality.     

A neural network approach for determining gait modifications to reduce the contact force in knee joint implant

There is a growing interest in non-surgical gait rehabilitation treatments to reduce the loading in the knee joint. In particular, synergetic kinematic changes required for joint offloading should be determined individually for each subject. Previous studies for gait rehabilitation designs are typically relied on a “trial-and-error” approach, using multi-body dynamic (MBD) analysis. However MBD is fairly time demanding which prevents it to be used iteratively for each subject.This study employed an artificial neural network to develop a cost-effective computational framework for designing gait rehabilitation patterns. A feed forward artificial neural network (FFANN) was trained based on a number of experimental gait trials obtained from literature. The trained network was then hired to calculate the appropriate kinematic waveforms (output) needed to achieve desired knee joint loading patterns (input). An auxiliary neural network was also developed to update the ground reaction force and moment profiles with respect to the predicted kinematic waveforms. The feasibility and efficiency of the predicted kinematic patterns were then evaluated through MBD analysis.Resuls showed that FFANN-based predicted kinematics could effectively decrease the total knee joint reaction forces. Peak values of the resultant knee joint forces, with respect to the bodyweight (BW), were reduced by 20% BW and 25% BW in the midstance and the terminal stance phases. Impulse values of the knee joint loading patterns were also decreased by 17% BW*s and 24%BW*s in the corresponding phases. The FFANN-based framework suggested a cost-effective forward solution which directly calculated the kinematic variations needed to implement a given desired knee joint loading pattern. It is therefore expected that this approach provides potential advantages and further insights into knee rehabilitation designs.