Comparison of strain-gage and fiber-optic goniometry for measuring knee kinematics during activities of daily living and exercise

There is increasing interest in wearable sensor technology as a tool for rehabilitation applications in community or home environments. Recent studies have focused on evaluating inertial based sensing (accelerometers, gyroscopes, etc.) that provide only indirect measures of joint motion. Measurement of joint kinematics using flexible goniometry is more direct, and still popular in laboratory environments, but has received little attention as a potential tool for wearable systems. The aim of this study was to compare two goniometric devices: a traditional strain-gauge flexible goniometer, and a fiberoptic flexible goniometer, for measuring dynamic knee flexion/extension angles during activity of daily living: chair rise, and gait; and exercise: deep knee bends, against joint angles computed from a "gold standard" Vicon motion tracking system. Six young adults were recruited to perform the above activities in the lab while wearing a goniometer on each knee, and reflective markers for motion tracking. Kinematic data were collected simultaneously from the goniometers (one on each leg) and the motion tracking system (both legs). The results indicate that both goniometers were within 2-5 degrees of the Vicon angles for gait and chair rise. For some deep knee bend trials, disagreement with Vicon angles exceeded ten degrees for both devices. We conclude that both goniometers can record ADL knee movement faithfully and accurately, but should be carefully considered when high (>120?deg) knee flexion angles are required.     

Shoulder muscle function depends on elbow joint position: an illustration of dynamic coupling in the upper limb

Shoulder muscle function has been documented based on muscle moment arms, lines of action and muscle contributions to contact force at the glenohumeral joint. At present, however, the contributions of individual muscles to shoulder joint motion have not been investigated, and the effects of shoulder and elbow joint position on shoulder muscle function are not well understood. The aims of this study were to compute the contributions of individual muscles to motion of the glenohumeral joint during abduction, and to examine the effect of elbow flexion on shoulder muscle function. A three-dimensional musculoskeletal model of the upper limb was used to determine the contributions of 18 major muscles and muscle sub-regions of the shoulder to glenohumeral joint motion during abduction. Muscle function was found to depend strongly on both shoulder and elbow joint positions. When the elbow was extended, the middle and anterior deltoid and supraspinatus were the greatest contributors to angular acceleration of the shoulder in abduction. In contrast, when the elbow was flexed at 90°, the anterior deltoid and subscapularis were the greatest contributors to joint angular acceleration in abduction. This dependence of shoulder muscle function on elbow joint position is explained by the existence of dynamic coupling in multi-joint musculoskeletal systems. The extent to which dynamic coupling affects shoulder muscle function, and therefore movement control, is determined by the structure of the inverse mass matrix, which depends on the configuration of the joints. The data provided may assist in the diagnosis of abnormal shoulder function, for example, due to muscle paralysis or in the case of full-thickness rotator cuff tears.     

Motion Control in Saccade and Smooth Pursuit for Bionic Eye Based on Three-dimensional Coordinates

Saccade and smooth pursuit are two important functions of human eye.In order to enable bionic eye to imitate the two functions,a control method that implements saccade and smooth pursuit based on the three-dimensional coordinates of target is proposed.An optimal observation position is defined for bionic eye based on three-dimensional coordinates.A kind of motion planning method with high accuracy is developed.The motion parameters of stepper motor consisting of angle acceleration and turning time are computed according to the position deviation,the target's angular velocity and the stepper motor's current angular velocity in motion planning.The motors are controlled with the motion parameters moving to given position with desired angular velocity in schedule time.The experimental results show that the bionic eye can move to optimal observation positions in 0.6 s from initial location and the accuracy of 3D coordinates is improved.In addition,the bionic eye can track a target within the error of less than 20 pixels based on three-dimensional coordinates.It is verified that saccade and smooth pursuit of bionic eye based on three-dimensional coordinates are feasible.     

Determining dual Euler angles of the ankle complex in vivo using "flock of birds" electromagnetic tracking device

The dual Euler angles method has been proposed as an alternative approach to describe the general spatial human joint motion. In this study, the dual Euler angles method was applied to study the three-dimensional motion of the ankle complex. The methodology for obtaining dual Euler angles of the ankle complex was developed by using a "Flock of Birds" electromagnetic tracking device. The repeatability of the methodology was studied based on the intertester and intratester variability analysis. Finally kinematic coupling characteristics of the ankle complex during dorsiflexion-plantarflexion, eversion-inversion, and abduction-adduction were analyzed according to the parameters of the dual Euler angles.     

Measurement of Shoulder Range of Motion in Patients with Adhesive Capsulitis Using a Kinect

Range of motion (ROM) measurements are essential for the evaluation for and diagnosis of adhesive capsulitis of the shoulder (AC). However, taking these measurements using a goniometer is inconvenient and sometimes unreliable. The Kinect (Microsoft, Seattle, WA, USA) is gaining attention as a new motion detecting device that is nonintrusive and easy to implement. This study aimed to apply Kinect to measure shoulder ROM in AC; we evaluated its validity by calculating the agreement of the measurements obtained using Kinect with those obtained using goniometer and assessed its utility for the diagnosis of AC. Both shoulders of 15 healthy volunteers and affected shoulders of 12 patients with AC were included in the study. The passive and active ROM of each were measured with a goniometer for flexion, abduction, and external rotation. Their active shoulder motions for each direction were again captured using Kinect and the ROM values were calculated. The agreement between the two measurements was tested with the intraclass correlation coefficient (ICC). Diagnostic performance using the Kinect ROM was evaluated with Cohen’s kappa value. The cutoff values of the limited ROM were determined in the following ways: the same as passive ROM values, reflecting the mean difference, and based on receiver operating characteristic curves. The ICC for flexion/abduction/external rotation between goniometric passive ROM and the Kinect ROM were 0.906/0.942/0.911, while those between active ROMs and the Kinect ROMs were 0.864/0.932/0.925. Cohen’s kappa values were 0.88, 0.88, and 1.0 with the cutoff values in the order above. Measurements of the shoulder ROM using Kinect show excellent agreement with those taken using a goniometer. These results indicate that the Kinect can be used to measure shoulder ROM and to diagnose AC as an alternative to goniometer.     

A procedure for determining angular positional data relative to the principal axes of the human body

This paper describes a simple computational procedure for determining angular displacement-time histories of human motion from three-dimensional cine data. The method is based on algebraic transformations of coordinates and coordinate axes. Through these coordinate transformations data was acquired for a multi-axial tumbling skill to illustrate angular displacement-time data relative to the moving coordinate system described by the human body through space.     

Quantitative measurement of spastic ankle joint stiffness using a manual device: A preliminary study

Quantitative measurement of ankle joint stiffness following stroke could prove useful in monitoring the progress of a rehabilitation programme. The objective of this study was to design a manual device for use in the clinical setting. Manual measurement of spastic ankle joint stiffness has historically been conducted using hand-held dynamometers or alternative devices, but some difficulties have been reported in controlling the velocity applied to the ankle during the measurement. In this study, a manually operated device was constructed with a footplate, a torquemeter and a potentiometer. It was mechanically designed to rotate around an approximated axis of the ankle joint and to measure ankle joint angular position and its corresponding resistive torque. Two stroke hemiplegic subjects pariticapted in a pilot study. The results suggested that difficulty in controlling the applied velocity might be complemented by presenting torque data as a function of peak angular velocity in each stretching cycle. Moreover, the results demonstrated that the device could potentially apply a wide range of angular velocities and provide potentially useful clinical information. Quantitative data successfully acquired using this method included the approximate ankle angular position, where the velocity-dependent characteristics of stiffness was notably initiated and its corresponding torque and velocity.     

A MR imaging procedure to measure tarsal bone rotations

Magnetic resonance imaging offers unique insights into three-dimensional foot bone motion. Thereby, adequate devices enabling defined loading and positioning of the foot are needed to profit from this noninvasive procedure. Tarsal bone positions of three healthy subjects were repeatedly measured in a pronated and a supinated foot excursion under bodyweight with a newly developed MR imaging procedure. The quantification of the transferred motion from the loading and positioning device to the calcaneus and an estimation of the required degrees to distinguish between tarsal joint rotations were used to evaluate the applicability of the procedure to investigate tarsal joint motion. It was found that 45-70% (75-95%) of the externally applied 15 deg foot pronation (supination) were transferred to the calcaneus. Furthermore, the talonavicular joint showed the largest amount of rotation up to 20 deg eversion-inversion and abadduction, followed by the subtalar joint showing nearly half of that motion. Considerably less motion was found between the cuboid and calcaneus (about 2-6 deg) and the cuboid nearly did not rotate relative to the navicular (on average 1 deg). The estimated necessary differences between tarsal joint movements to identify individual kinematic behavior were in the order of 2 deg (4 deg related to the talonavicular joint). Since the results were in agreement with the literature, it is concluded that the applicability of the presented procedure to investigate tarsal bone mechanics is warranted. The possibility to evaluate 3D tarsal joint motion in combination with bone morphology (e.g., joint curvature) may provide new insights in the still uncertain relationship between foot function and foot morphology.     

On the estimation of joint kinematics during gait.

In gait analysis, the concepts of Euler and helical (screw) angles are used to define the three-dimensional relative joint angular motion of lower extremities. Reliable estimation of joint angular motion depends on the accurate definition and construction of embedded axes within each body segment. In this paper, using sensitivity analysis, we quantify the effects of uncertainties in the definition and construction of embedded axes on the estimation of joint angular motion during gait. Using representative hip and knee motion data from normal subjects and cerebral palsy patients, the flexion-extension axis is analytically perturbed +/- 15 degrees in 5 degrees steps from a reference position, and the joint angles are recomputed for both Euler and helical angle definitions. For the Euler model, hip and knee flexion angles are relatively unaffected while the ab/adduction and rotation angles are significantly affected throughout the gait cycle. An error of 15 degrees in the definition of flexion-extension axis gives rise to maximum errors of 8 and 12 degrees for the ab/adduction angle, and 10-15 degrees for the rotation angles at the hip and knee, respectively. Furthermore, the magnitude of errors in ab/adduction and rotation angles are a function of the flexion angle. The errors for the ab/adduction angles increase with increasing flexion angle and for the rotation angle, decrease with increasing flexion angle. In cerebral palsy patients with flexed knee pattern of gait, this will result in distorted estimation of ab/adduction and rotation. For the helical model, similar results are obtained for the helical angle and associated direction cosines.(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of dual Euler angles to quantify the three-dimensional joint motion and its application to the ankle joint complex

This paper presents a modified Euler angles method, dual Euler angles approach, to describe general spatial human joint motions. In dual Euler angles approach, the three-dimensional joint motion is considered as three successive screw motions with respect to the axes of the moving segment coordinate system; accordingly, the screw motion displacements are represented by dual Euler angles. The algorithm for calculating dual Euler angles from coordinates of markers on the moving segment is also provided in this study. As an example, the proposed method is applied to describe motions of ankle joint complex during dorsiflexion–plantarflexion. A Flock of Birds electromagnetic tracking device (FOB) was used to measure joint motion in vivo. Preliminary accuracy tests on a gimbal structure demonstrate that the mean errors of dual Euler angles evaluated by using source data from FOB are less than 1° for rotations and 1 mm for translations, respectively. Based on the pilot study, FOB is feasible for quantifying human joint motions using dual Euler angles approach.     

Goniometric measurement of hip motion in cycling while standing

The purpose of this study was to develop an instrument for quantifying the motion of the hip relative to the bicycle while cycling in the standing position. Because of the need to measure hip motion on the road as well as in the laboratory, a goniometer which locates the hip using spherical coordinates was designed. The goniometer is presented first, followed by the development of the equations that enable the distance from the joint center to the pedal spindle to be determined. The orientation of this line segment is specified by calculating two angles referenced to the frame. Also outlined are the procedures used to both calibrate the goniometer and perform an accuracy check. The results of this check indicate that the attachment point of the goniometer to the rider can be located to within 2.5 mm of the true position. The goniometer was used to record the hip movement patterns of six subjects who cycled in the standing position on a treadmill. Representative results from one test subject who cycled at 6% grade and 25 km h-1 are presented. Results indicate that the bicycle is leaned from side to side with the frequency of leaning equal to the frequency of pedalling. Extreme lean angles are +/- 6 degrees. The distance from the hip to the pedal varies approximately sinusoidally with frequency equal to pedalling rate and amplitude somewhat less than crank arm length. The absolute elevation of the hip, however, exhibits two cycles for each crank cycle. Asymmetry in the plot of elevation over a single crank cycle indicates that the pelvis rocks from side to side and that the elevation of the pelvis midpoint changes. Extreme values of the pelvis rocking angle are +/- 12 degrees. Highest pelvis midpoint elevations, however, do not occur at the same crank angles as those angles at which the pelvis rocking is extreme. It appears that the vertical motion of the hips affects pedalling mechanics when cycling in the standing position.     

Apparatus to obtain rotational flexibility of the human knee under moment loads in vivo

The contributions of this paper are twofold. One is the design and performance evaluation of new equipment to determine the rotational flexibility of the human knee in vivo. Since determining knee flexibility requires the application of external loads and the measurement of knee rotations, the new equipment consists of a load application stand and a triaxial goniometer. The triaxial goniometer noninvasively mounts to the leg and directly measures the relative three degrees-of-freedom rotations of the knee sequentially and independently. The goniometer incorporates several unique design features which enhance measurement accuracy. The load stand applies pure varus/valgus and external/internal axial moments either individually or in combination through the use of motors controlled by the test subject. Unique to this design are features which enable the application of moments to the knee which minimise shear forces. Other unique design features permit the stand to control hip and knee flexion angles, muscle contraction, and axial loading. To assess the accuracy with which rotations are measured during experiments, three tests were conducted with the equipment. One test evaluated the inherent accuracy of the goniometer, a second test assessed the potential for goniometer slippage during loading, and a third explored the effect of goniometer mounting on the repeatability of results. A special verification apparatus facilitated evaluation of goniometer inherent accuracy. A second contribution of the paper is an investigation of the effect of foot constraints (i.e. boundary conditions) on flexibility results. To make this investigation, three subjects were tested with the knee at 15 degrees of flexion. Results revealed large differences in flexibility between constraining the foot in both external/internal and varus/valgus rotations and permitting the foot to rotate freely in the direction not being loaded. Further, constraint moments as high as 23 Nm were also recorded. These results emphasise that in order to obtain accurate flexibility results for isolated loads, the foot must be unconstrained by the loading apparatus.     

Helical motion analysis of the knee--I. Methodology for studying kinematics during locomotion

A technique for investigating the three-dimensional kinematics of knee motion during dynamic functional tasks has been developed. It involves the combined usage of a six degree of freedom goniometer and helical motion analysis. A detailed procedure for coordinate system alignment and calibration must be followed. Once established this entire procedure is routinely implementable. Ensemble averages from multiple walking strides reveal that this technique is sensitive enough to differentiate between the kinematics of an uninjured and injured knee.     

Kinetic chain of overarm throwing in terms of joint rotations revealed by induced acceleration analysis

This study investigated how baseball players generate large angular velocity at each joint by coordinating the joint torque and velocity-dependent torque during overarm throwing. Using a four-segment model (i.e., trunk, upper arm, forearm, and hand) that has 13 degrees of freedom, we conducted the induced acceleration analysis to determine the accelerations induced by these torques by multiplying the inverse of the system inertia matrix to the torque vectors. We found that the proximal joint motions (i.e., trunk forward motion, trunk leftward rotation, and shoulder internal rotation) were mainly accelerated by the joint torques at their own joints, whereas the distal joint motions (i.e., elbow extension and wrist flexion) were mainly accelerated by the velocity-dependent torques. We further examined which segment motion is the source of the velocity-dependent torque acting on the elbow and wrist accelerations. The results showed that the angular velocities of the trunk and upper arm produced the velocity-dependent torque for initial elbow extension acceleration. As a result, the elbow joint angular velocity increased, and concurrently, the forearm angular velocity relative to the ground also increased. The forearm angular velocity subsequently accelerated the elbow extension and wrist flexion. It also accelerated the shoulder internal rotation during the short period around the ball-release time. These results indicate that baseball players accelerate the distal elbow and wrist joint rotations by utilizing the velocity-dependent torque that is originally produced by the proximal trunk and shoulder joint torques in the early phase.     

Modeling of the knee joint load in rehabilitative knee extension exercises under water

A biomechanical and hydrodynamic theoretical model has been developed in order to calculate the knee joint load during underwater knee extension exercises. The hydrodynamic force has been evaluated within the framework of a strip-theory approach, when a blunt rectangular resistive device is applied proximally to the shank to increase its frontal area. Analytical expressions of the patellar tendon force (F(PT)), the axial (phi(n)) and the shear (phi(t)) component of the tibiofemoral joint load have been derived as a function of joint angle (theta), angular velocity (theta ), angular acceleration (theta ), resistive device density, length (L(x)), width (L(z)) and thickness, and average hydrodynamic drag and added mass coefficients. An inverse dynamic problem has been solved, assuming for theta and theta a dependence on theta consistent with the experimental kinematic data available in the literature. The results highlight that the characteristics of the resistive device and the level of muscular activation can be adjusted reciprocally in order to control the peak value of F(PT), phi(n) and phi(t), and the position of these peaks within the joint range of motion (ROM). No anterior cruciate ligament (ACL) stress is observed (phi(t)>0) over the whole ROM, independent of the level of muscular activation, for a light resistive device with L(x) < or = 0.3 m and L(z) < or = 0.4 m. This work highlights that aquatic exercises can be usefully and safely implemented in the rehabilitation program following ACL surgery, and whenever it is important to avoid excessive shear joint forces that constrain the tibial plateau anterior translation with respect to the femur.     

Evaluation of the kinematic parameters of normal-paced gait in subjects with gonarthrosis and the influence of gonarthrosis on the function of the ankle joint and hip joint

The aim of the study was to assess the variability of parameters characterising the gait of persons suffering from degenerative changes of the knee joint and their influence on the ankle and hip joints. The values of the angular changes in the knee, ankle and hip joints in the three planes of motion were assessed. Locomotion tests were performed on 27 persons, aged between 60 and 74, using Vicon 250, the three-dimensional analysis system. The sharpest deviations from the results of the control group were revealed in the transverse and frontal planes. Degenerative knee joint disease has changed the gait stereotype causing a reduction in the economy of gonarthrosis patients' locomotion, the influence of the disease on the function of the neighbouring joints is also distinctly marked.     

Three-dimensional kinematics of the human knee during walking.

Three-dimensional kinematics of the tibiofemoral joint were studied during normal walking. Target markers were fixed to tibia and femur by means of intra-cortical traction pins. Radiographs of the lower limb were obtained to compute the position of the target markers relative to internal anatomical structures. High-speed cine cameras were used to measure three-dimensional coordinates of the target markers in five subjects walking at a speed of 1.2 m s-1. Relative motion between tibia and femur was resolved according to a joint coordinate system (JCS). The measurements have identified that substantial angular and linear motions occur about and along each of the JCS axes during walking. The results do not, however, support the traditional view that the so-called 'screw home' mechanism of the knee joint operates during gait.     

Can one angle be simply subtracted from another to determine range of motion in three-dimensional motion analysis?

To determine the range of motion of a joint between an initial orientation and a final orientation, it is convenient to subtract initial joint angles from final joint angles, a method referred to as the vectorial approach. However, for three-dimensional movements, the vectorial approach is not mathematically correct. To determine the joint range of motion, the rotation matrix between the two orientations should be calculated, and angles describing the range of motion should be extracted from this matrix, a method referred to as the matrical approach. As the matrical approach is less straightforward to implement, it is of interest to identify situations in which the vectorial approach leads to insubstantial errors. In this study, the vectorial approach was compared to the matrical approach, and theoretical justification was given for situations in which the vectorial approach can reasonably be used. The main findings are that the vectorial approach can be used if (1) the motion is planar (Woltring HJ. 1994. 3-D attitude representation of human joints: a standardization proposal. J Biomech 27(12): 1399–1414), (2) the angles between the final and the initial orientation are small (Woltring HJ. 1991. Representation and calculation of 3-D joint movement. Hum Mov Sci 10(5): 603–616), (3) the angles between the initial orientation of the distal segment and the proximal segment are small and finally (4) when only one large angle occurs between the initial orientation of the distal segment and the proximal segment and the angle sequence is chosen in such a way that this large angle occurs on the first axis of rotation. These findings provide specific criteria to consider when choosing the angle sequence to use for movement analysis.     

Crouched postures reduce the capacity of muscles to extend the hip and knee during the single-limb stance phase of gait

Many children with cerebral palsy walk in a crouch gait that progressively worsens over time, decreasing walking efficiency and leading to joint degeneration. This study examined the effect of crouched postures on the capacity of muscles to extend the hip and knee joints and the joint flexions induced by gravity during the single-limb stance phase of gait. We first characterized representative mild, moderate, and severe crouch gait kinematics based on a large group of subjects with cerebral palsy (N=316). We then used a three-dimensional model of the musculoskeletal system and its associated equations of motion to determine the effect of these crouched gait postures on (1) the capacity of individual muscles to extend the hip and knee joints, which we defined as the angular accelerations of the joints, towards extension, that resulted from applying a 1N muscle force to the model, and (2) the angular acceleration of the joints induced by gravity. Our analysis showed that the capacities of almost all the major hip and knee extensors were markedly reduced in a crouched gait posture, with the exception of the hamstrings muscle group, whose extension capacity was maintained in a crouched posture. Crouch gait also increased the flexion accelerations induced by gravity at the hip and knee throughout single-limb stance. These findings help explain the increased energy requirements and progressive nature of crouch gait in patients with cerebral palsy.     

Calculation of the instantaneous centre of rotation for a rigid body

The mathematical procedure presented is used for the calculation of the instantaneous centre of rotation for a rigid body based on kinematic measurement data. For every rotation angle interval observed an average centre of rotation is calculated by an appropriate optimizing calculation similar to data approximation by moving average. Practical applicability of this procedure has been proved by means of two planar and one three-dimensional test measurements of known movements (pure rotation, rolling motion and motion of a ball-and-socket joint.