Smartphone-based accelerometry is a valid tool for measuring dynamic changes in knee extension range of motion

Introduction

Measurement of static joint range of motion is used extensively in orthopaedic and rehabilitative communities to benchmark treatment efficacy. Static measures are, however, insufficient in providing detailed information about patient impairments. Dynamic range of motion measures could provide more detailed information about patient impairments thus leading to better clinical assessments. Reliable and valid methods are available, but due to limitations in the present technology, dynamic measures are seldom performed in clinical settings. The objective of this study was to determine the validity of smartphone-based accelerometry measuring the dynamic range of motion of the knee joint during a passively executed extension movement.

Reliability and validity of a new ankle electrogoniometer

Objectives:?To establish reliability, accuracy and concurrent validity of a new electrogoniometer (SG110A, Biometrics) for measuring ankle movement.

Methods:?The new electrogoniometer, placed at the lateral malleolus (A-perp), was compared to a customary electrogoniometer (SG110, Biometrics), placed along the Achilles tendon (A-para). Concurrent recordings were made with motion analysis. Common dance movements were performed by 17 dancers on two days. Intraclass correlation coefficients (ICC) and standard error of measurement (SEM) were calculated for sagittal angular displacements.

Results:?Instrument and intra-tester reliability of A-perp was high (r?≥?0.985, r?≥?0.979, respectively). Criterion and concurrent validity were also high (r?≥?0.954, r?≥?0.937). SEM ranged from 1.43° to 6.99°.

Conclusions:?The high ICC values establish acceptable reliability and validity. Subjects found A-perp more comfortable. Although both electrogoniometers are acceptable (comparable SEM) to measure extreme ankle motions, the greater comfort and durability of the new A-perp sensor is advantageous.     

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.     

前交叉韧带损伤膝关节6个自由度静态加载体的稳定性*☆

背景：由于膝关节的体外标本无法模拟膝关节的真实运动,而体内的运动测试又无法获得骨结构的运动信息,因而不能得到准确的膝关节稳定性数据,也就无法对膝关节损伤的早期诊断及防治措施进行深入的研究。 目的：应用计算机三维重建技术、2D/3D图像配准技术及图像处理技术对前交叉韧带损伤膝关节6个自由度变化进行静态加载体内稳定性测试。 方法：8例患者单侧膝关节前交叉韧带断裂而对侧正常,膝关节在屈曲0°,30°,60°和90°时分别进行134 N前加载。采集各角度相互垂直的2D图像,与3D CT图像在虚拟X射线投射系统进行2D/3D图像配准,还原膝关节不同角度时的股骨和胫骨相对3D位置关系,获得膝关节6个自由度数据。 结果与结论：前交叉韧带断裂后胫骨前移均明显增加,在完全伸直(0°)时胫骨前移最小,胫骨前移在30°时达到最大;胫骨前移在60°和90°时逐渐减小,各角度间比较差异均有显著性意义(P=0.000)。前交叉韧带断裂后,膝关节胫骨内旋、内移均较健侧增加(P=0.000)。提示通过2D/3D图像配准技术可以实现对膝关节静态加载的体内稳定性分析;前交叉韧带损伤后膝关节前移、内旋和内移均明显增加。     

Validity and reliability of smartphones in measuring joint position sense among asymptomatic individuals and patients with knee osteoarthritis: A cross-sectional study

BackgroundQuantifying proprioception deficit in patients with osteoarthritis (OA) may be important in evaluating treatment effectiveness. This study investigated the concurrent and known-groups validity as well as test–retest reliability of a smartphone application in assessing joint position sense (JPS) in asymptomatic individuals and patients with knee OA.MethodsSixty-four knees, from 16 asymptomatic controls and 16 patients with bilateral OA, were assessed twice with a 1-week interval in between. The smartphone Goniometer Pro application and isokinetic dynamometer simultaneously quantified JPS, in terms of absolute repositioning error (RE) angle, during active and passive limb movements at selected angles.ResultsBoth devices showed moderate to almost perfect correlations in measuring JPS; whether active (intra-class correlation coefficient (ICC) >0.87) or passive (ICC >0.97). The mean RE angle differences between the two devices were <0.77° (passive JPS) and <2.76° (active JPS). Both devices were capable of distinguishing patients and asymptomatic controls at 55° and 80°. The smartphone showed moderate test–retest reliability of active JPS measurement (ICC = 0.51) in the two groups, similar to that of the isokinetic dynamometer (ICC = 0.62), but with a high measurement error.ConclusionsSmartphone application is a valid alternative to the isokinetic dynamometer in assessing JPS in patients with knee OA and asymptomatic controls. The two devices could distinguish patients and asymptomatic volunteers during passive JPS measured at 55° and 80°. Both devices have moderate reliability in quantifying active JPS, but reliability results should be considered with caution.     

Ambulatory measurement of shoulder and elbow kinematics through inertial and magnetic sensors

Inertial and magnetic measurement systems (IMMSs) are a new generation of motion analysis systems which may diffuse the measurement of upper-limb kinematics to ambulatory settings. Based on the MT9B IMMS (Xsens Technologies, NL), we therefore developed a protocol that measures the scapulothoracic, humerothoracic and elbow 3D kinematics. To preliminarily evaluate the protocol, a 23-year-old subject performed six tasks involving shoulder and elbow single-joint-angle movements. Criteria for protocol validity were limited cross-talk with the other joint-angles during each task; scapulohumeral-rhythm close to literature results; and constant carrying-angle. To assess the accuracy of the MT9B when measuring the upper-limb kinematics through the protocol, we compared the MT9B estimations during the six tasks, plus other four, with the estimations of an optoelectronic system (the gold standard), in terms of RMS error, correlation coefficient (r), and the amplitude ratio (m). Results indicate that the criteria for protocol validity were met for all tasks. For the joint angles mainly involved in each movement, the MT9B estimations presented RMS errors <3.6°, r > 0.99 and 0.9 < m < 1.09. It appears therefore that (1) the protocol in combination with the MT9B is valid for, and (2) the MT9B in combination with the protocol is accurate when, measuring shoulder and elbow kinematics, during the tasks tested, in ambulatory settings.     

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.     

枕颈部三维运动范围的测量

目的：研究枕颈部正常的三维运动范围，为枕颈部不稳分析和治疗提供生物力学基础。方法：运用脊柱三维运动测量分析系统，对１１具成人新鲜枕颈部标本的三维运动范围进行测试。结果：寰枕关节的前屈、后伸、左／右侧屈、左／右轴向旋转运动范围分别是：１１．７°、９．６°、２．８°／２．７°、６．９°／５．４°；寰枢关节分别为：８．９°、５．９°、３．４°／４．２°、３７．５°／３８．７°；寰枢关节中性区为２７．４°，占主运动范围的７１．７％；枕颈部与脊柱其它部位相比，主运动时伴有更明显的藕合运动，屈伸、侧屈时伴有比主运动范围更大的藕合旋转运动，分别为１０．５°、１４．３°。结论：脊柱三维测试分析系统不仅能对枕颈部的三维运动范围进行精确的测量，且能反映枕颈部三维运动的特点。     

Digital goniometric measurement of knee joint motion. Evaluation of usefulness for research settings and clinical practice

An accurate and reproducible measurement method for joint motion is essential for classification of success or failure in therapeutic intervention. Digital goniometry is increasingly used as a method of classification for knee joint excursion. The reliability of goniometry however remains debatable. Aim of the study was to determine both intra- and inter-rater reproducibility in degrees, with an electronic digital inclinometer (EDI 320) for active and passive maximum flexion and active maximum extension of the knee joint and to determine the reproducibility of active and passive range of motion. A classical crossover design, with strict measurement protocol was used. Two raters measured 72 knee motions each, in 42 healthy subjects in four sessions. The smallest detectable difference (SDD) was calculated by using adjusted Bland and Altman plots for each knee excursion. No differences in joint excursions between the sexes were found. Passive maximum flexion showed larger excursions than active maximum flexion with additional higher levels of reproducibility. SDDs for inter-rater comparisons yielded: 0+/-3.9 degrees for active maximum extension, 0+/-7.4 degrees for active maximum flexion, 0+/-6.4 degrees for passive maximum flexion, 0+/-7.6 degrees for AROM and 0+/-5.4 degrees for PROM. Intra-rater SDDs showed increased reproducibility by 0.4-1.9 degrees. We conclude that interpretation of knee joint excursions in clinical settings is with these SDDs. Clinical and statistical differences in research settings within these SDDs are not a true difference but should be attributed to measurement error.     

A systematic review to determine the reliability of knee joint position sense assessment measures

BackgroundThe assessment of joint position sense (JPS) is the most widely used measurement of knee proprioceptive capability within the literature. However, it remains unclear what the most reliable method is to assess this. The purpose of this study was to determine the intra- and inter-rater reliability of the various methods used to assess knee JPS.MethodsA systematic review of published and unpublished literature sources was conducted up to June 2012. All studies principally assessing the reliability (intra- or inter-rater) or reproducibility of a JPS of the knee were included. The methodological quality of each study was reviewed using the Critical Appraisal Skills Programme tool.ResultsA total of 18 studies were eligible, assessing the reliability of JPS with 456 knees. The reliability of four methods of JPS has been recorded: position replication using a model, image recorded angulation, electrogoniometry and dynamometry/angular motion chair. Intra-rater reliability was good for the assessment of JPS using photographs and digital images, and replicating knee position using a paper model, this was good but variable when electrogoniometry was used, and moderate but variable when assessed using dynamometry/angle motion chairs. The assessment of JPS by image recorded angulation, electrogoniometry and dynamometry/angular motion chair has demonstrated good inter-rater reliability.ConclusionsWhilst JPS methods appear to have variable reliability, the four assessment methods should be further assessed with pathological populations such as those following patellar dislocation or anterior cruciate ligament rupture. This will better facilitate the generalisability of JPS assessment methods to inform clinical practice.     

坡面步行中青年女性下肢关节角及肌肉激活度

目的通过定量分析关节角及主要肌肉激活度的变化来说明步行速度和路面坡度对下肢运动的影响。方法首先按由慢到快选择了共5种步行速度,由低到高选择3种坡度,并利用运动捕捉系统对15各青年女性的步态进行测量,同时对影响下肢运动的8块主要肌肉的肌电信号进行了采集。然后通过计算分析获得她们在不同步行速度和路面坡度下髋、膝及踝关节矢状面的关节角度变化的均值,从测量数据中寻找出一个最接近这个均值曲线的研究对象。结果计算获得了该研究对象不同步行速度和路面坡度下踝关节、膝关节及髋关节在一个步态周期内的矢状面关节角的变化曲线以及主要肌肉的激活度变化曲线。结论每个步态周期内,关节角及肌肉激活度在5种不同速度下的变化很小;而在3种不同路面坡度下的变化仅趋势基本一致,峰值的差异却非常明显。     

Comparative abilities of Microsoft Kinect and Vicon 3D motion capture for gait analysis

Biomechanical analysis is a powerful tool in the evaluation of movement dysfunction in orthopaedic and neurologic populations. Three-dimensional (3D) motion capture systems are widely used, accurate systems, but are costly and not available in many clinical settings. The Microsoft Kinect? has the potential to be used as an alternative low-cost motion analysis tool. The purpose of this study was to assess concurrent validity of the Kinect? with Brekel Kinect software in comparison to Vicon Nexus during sagittal plane gait kinematics. Twenty healthy adults (nine male, 11 female) were tracked while walking and jogging at three velocities on a treadmill. Concurrent hip and knee peak flexion and extension and stride timing measurements were compared between Vicon and Kinect?. Although Kinect measurements were representative of normal gait, the Kinect? generally under-estimated joint flexion and over-estimated extension. Kinect? and Vicon hip angular displacement correlation was very low and error was large. Kinect? knee measurements were somewhat better than hip, but were not consistent enough for clinical assessment. Correlation between Kinect? and Vicon stride timing was high and error was fairly small. Variability in Kinect? measurements was smallest at the slowest velocity. The Kinect? has basic motion capture capabilities and with some minor adjustments will be an acceptable tool to measure stride timing, but sophisticated advances in software and hardware are necessary to improve Kinect? sensitivity before it can be implemented for clinical use.     

Accuracy of classifying the movement strategy in the functional reach test using a markerless motion capture system

The purpose of this study was to examine the accuracy of classifying the movement strategy in the functional reach test (FRT) using a markerless motion capture system (MLS) on the basis of values acquired with a marker-based motion capture system (MBS). Sixty young, injury-free individuals participated in this study. The task action involved reaching forward in the standing position. Using the Microsoft Kinect v2 as an MLS and Vicon as a MBS, the coordinates of the hip joints, knee joints and ankle joints were measured. The hip and ankle joint angles during the task were calculated from the coordinate data. These angles between MLS and MBS were compared using a paired t-test. The accuracy of movement strategy defined using MLS was examined based on the MBS. A t-test showed a significant difference in both the hip and ankle joint angles between systems (p?<?.01). However, in case of using data of left ankle joint, indices of the classification accuracy of MLS were 0.825 for sensitivity, 1.000 for specificity, infinity for positive likelihood ratio and 0.175 for negative likelihood ratio. The results for the right joint angle were similar to those of the left joint angle. Although the absolute measures in the hip and joint angles obtained using MLS differ from MBS, the MLS may be useful for accurately classifying the movement strategy adopted in the FRT.     

小腿截肢患者不同路况下膝关节动态载荷研究

研究截肢患者行走过程中的膝关节动态载荷是膝关节损伤康复和假肢设计的基础。本研究以小腿截肢患者为研究对象,建立了膝关节动态载荷三维计算模型,通过平地行走、上、下楼梯三种路况下的步态分析,对一个步态周期内的膝关节载荷进行了计算分析。结果表明,各种路况下患者的步态特征和膝关节载荷各不相同,虽然总体变化规律基本一致,但上下楼梯时的小腿运动范围、地面反力和膝关节载荷比平地行走时幅值较大。这些定量分析结果为小腿截肢患者步态分析和假肢设计提供了理论依据。     

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...     

Superposition of independent units of coordination during pointing movements involving the trunk with and without visual feedback

Previous studies addressing the problem of the control of multiple degrees of freedom have examined the influence of trunk movement on pointing movements within the arm's reach. Such movements may be controlled by two functionally independent units of coordination (synergies): one involving only arm joints and producing the hand trajectory to the target (the transport synergy), and the other coordinating trunk and arm movements leaving the hand trajectory unchanged (the compensatory synergy). The question of whether or not this functional subdivision depends on visual feedback was addressed in the present study. We also tested whether or not the motor effects of different synergies are summated as independent components, a control strategy called "superposition." Finally, we investigated whether or not the relationship between different degrees of freedom within each synergy could be considered linear resulting in proportional changes in different joint angles. Seated subjects produced fast, uncorrected arm movements to an ipsi- or a contralateral target in the direction of +/-45 degrees to the sagittal midline of the trunk. Targets could be reached using the arm alone (control trials) or by combining the arm motion with a forward or backward trunk motion produced by hip flexion or extension (test trials), with and without visual feedback. The shape of the hand trajectory, its direction and tangential velocity, movement precision, joint angles and the sequence of the trunk and hand recruitment and de-recruitment were measured. In both visual conditions, the direction of the hand trajectory observed in control trials was generally preserved in test trials. In terms of sequencing, even in the absence of vision, the trunk movement was initiated before the onset of and outlasted the hand shift, indicating that the potential influence of the trunk on the hand movement was compensated by rotations in the elbow and shoulder joint. The analysis of other variables also implied that the effects of trunk recruitment on the hand trajectory were minor compared to those which could be observed if these effects were not compensated by appropriate changes in the arm joint angles. It was concluded that an arm-trunk compensatory synergy is present in pointing movements regardless of visual feedback. Principal component analysis showed that the relationship between elbow, shoulder and hip joint angles in individual arm and combined arm-trunk movements cannot be considered linear, implying that this relationship is adjusted according to the changing arm geometry. The changes in each arm joint angle (elbow, shoulder) elicited by a forward trunk bending in one block of trials were compared with those elicited by a backward bending in another block, whereas the hand moved to the same target in both blocks. These changes were opposite but of similar magnitude. As a result, for each moment of movement, the mean joint angle obtained by averaging across two directions of trunk motion was practically identical to that in control trials in which the trunk was motionless. It is concluded that the transport and arm-trunk compensatory synergies are combined as independent units, according to the principle of superposition. This principle may simplify the control of the coordination of a redundant number of degrees of freedom.     

Reliability of a technique for determining sagittal knee geometry from lateral knee radiographs

The purposes of this study were to describe an analytical technique for determining selected 2-dimensional geometric characteristics of a knee joint using lateral knee radiographs and to examine the inter- and intra-analyst reliability of this technique. Five lateral knee radiographs of different knee flexion angles (25-85 degrees at intervals of 15 degrees ) were obtained from five subjects. Two graduate and five undergraduate students with knowledge of knee anatomy served as the analysts and were asked to identify certain landmarks from the radiographs. The coordinates of these landmarks were used to determine the effective moment arm of the quadriceps force, patellar tendon length, patella height, patellar mechanism and patellar tendon angles, and tibiofemoral and patellofemoral joint spaces. For each radiograph, intraclass correlation coefficients (ICCs) were computed for combinations of 2-7 analysts. Using all seven analysts, the ICCs ranged from 0.9967 to 0.9985 for different radiographs. When fewer analysts were used, the average ICCs were 0.9975 (6 analysts), 0.9974 (5 analysts), 0.9974 (4 analysts), 0.9974 (3 analysts), and 0.9973 (2 analysts). Four of the analysts re-analyzed the radiographs 2-3months after the initial analyses. Intra-analyst ICCs ranged from 0.9842 to 0.9999. Overall, the high ICC values indicate excellent inter- and intra-analyst reliability. The proposed technique is reliable and may be used for both clinical and research purposes. The relatively small reductions in ICCs when fewer analysts were used suggest that a single experienced analyst is sufficient for clinical assessment. However, 2-3 analysts are recommended for research purposes.     

腰椎后部结构的运动学分析

以人体完整腰椎作为实验标本，设计和应用平行光三维运动测量系统，获得各向运动时腰椎后部结构特定点的三维运动参数。通过载荷－位移曲线分析，发现腰椎后部结构重要部位的立体运动规律。右旋时右侧腰４下关节突的相对运动是后移０．６ｍｍ；上移１．０ｍｍ和右移３．０ｍｍ，扩大了腰５神经根管的容积。前屈时，无论那一个腰椎节段，均发生向前、上方的运动，侧向移位较。老年腰椎标本不同节段的主运动轴在Ｘ和Ｚ轴不规律更换，加载过程中位移量变化较中青年标本大，这与标本的退变和稳定性变化有关。     

The quality of bone surfaces may govern the use of model based fluoroscopy in the determination of joint laxity

The assessment of knee joint laxity is clinically important but its quantification remains elusive. Calibrated, low dosage fluoroscopy, combined with registered surfaces and controlled external loading may offer possible solutions for quantifying relative tibio-femoral motion without soft tissue artefact, even in native joints. The aim of this study was to determine the accuracy of registration using CT and MRI derived 3D bone models, as well as metallic implants, to 2D single-plane fluoroscopic datasets, to assess their suitability for examining knee joint laxity.Four cadaveric knees and one knee implant were positioned using a micromanipulator. After fluoroscopy, the accuracy of registering each surface to the 2D fluoroscopic images was determined by comparison against known translations from the micromanipulator measurements. Dynamic measurements were also performed to assess the relative tibio-femoral error. For CT and MRI derived 3D femur and tibia models during static testing, the in-plane error was 0.4 mm and 0.9 mm, and out-of-plane error 2.6 mm and 9.3 mm respectively. For metallic implants, the in-plane error was 0.2 mm and out-of-plane error 1.5 mm. The relative tibio-femoral error during dynamic measurements was 0.9 mm, 1.2 mm and 0.7 mm in-plane, and 3.9 mm, 10.4 mm and 2.5 mm out-of-plane for CT and MRI based models and metallic implants respectively. The rotational errors ranged from 0.5° to 1.9° for CT, 0.5–4.3° for MRI and 0.1–0.8° for metallic implants.The results of this study indicate that single-plane fluoroscopic analysis can provide accurate information in the investigation of knee joint laxity, but should be limited to static or quasi-static evaluations when assessing native bones, where possible. With this knowledge of registration accuracy, targeted approaches for the determination of tibio-femoral laxity could now determine objective in vivo measures for the identification of ligament reconstruction candidates as well as improve our understanding of the consequences of knee joint instability in TKA.     

Development of computer-based environment for simulating the voluntary upper-limb movements of persons with disability

Upper-limb orthotic systems have been designed for restoring the upperlimb functions of individuals with disabilities resulting from spinal cord injury (SCI), stroke and muscular dystrophy. These systems employ either functional electrical stimulation or external power. It is proposed that, instead of time-consuming and complicated monitoring using sensors and motion analysis, a software simulator with both angular displacement and acceleration parameters can facilitate the design of a control strategy for an orthosis. Reaching movements of three cervical SCI subjects are used to verify the simulator. A motion analysis system is used to measure the range of motion and joint angles during hand reaching. Results indicate that quaternion and spline curve techniques are suitable for interpolation of the hand reaching movements. The information needed for good simulation only compress the shoulder and elbow joint angles in a few key postures. Stimulated acceleration signals on the upper-arm segment have a high correlation coefficient (>0.9) and a small root mean squared error (<0.11 g) with a real bi-axial accelerometer.