The reiterative accuracy of gait determined by simplified gait analysis

Dynamic perception is the perception of the relation of moving body parts to each other. To examine dynamic perception, the reiterative accuracy of well-known movements - for example, gait - is analysed. Simplified gait analysis can be obtained for 50 cycles of gait in this research. The high number of gait cycles analysed provides an opportunity to calculate the average and standard deviation of different temporal (duration of stance phase, swing phase, double support phase) and spatial parameters (step length, stride length, cadence) of each subject investigated. 45 healthy, young subjects, 11 professional hand ball players, 24 patients after medial meniscectomy, 20 elderly, healthy subjects, and 20 patients with hip osteoarthritis are investigated. The average, standard deviation and normalized deviation of parameters of each person are calculated. The normalized deviation of parameters enables modelling of dynamic perception, because it is independent from the value of parameters due to normalization. O ur tests show that the size of the parameter is independent from lateral dominance at healthy subjects. The size of the normalized deviation of parameters depends on age, on the intensity of sports activities, and on orthopaedical diseases

Verification of determining the spatial position of the lower extremity by ultrasound-based motion analyser

The objective of this study is to verify the ultrasound-based motion analysis method on 16 healthy people during gait. Ultrasound-based triplets were fixed onto the sacrum, the left and right thighs and the left and right calves. A ZEBRIS ultrasound-based motion analysis system was used for measuring the spatial coordinates of triplets during gait. The position of the nineteen anatomical points involved in the study was defined by an ultrasound-based pointer in the local coordinate system specified by the triplets before starting measurements. The spatial coordinates of the designated anatomical points can be calculated from the coordinate of triplets. The method is calibrated with interobserver and intraobserver variations. On the basis of the statistical analysis of the spatial coordinates specified by the ultrasound-based measurement method, it can be established that the measurement method is reproducible because in case of an experienced person performing measurements the maximum standard deviation of co ordinates is below 1 mm, and around 2 mm in case of a person inexperienced in measurements

Verification of determining the curvatures and range of motion of the spine by electromechanical-based skin-surface device

There is an increasing awareness of the risk and dangers of exposure to radiation associated with repeated radiographic assessment of spinal curvature and spinal movement. As such, attempts are continuously being made to develop skin surface devices for use in examining the progression and response to treatment of various spinal disorders. However, devices must be verified before use in research or in a clinical environment. The aim of this study was to examine the reliability of measurements using a skin-surface device, the Spinal Mouse on 30 healthy volunteers. Spinal curvature was measured with the Spinal Mouse during standing, flexion, and extension (each five times by each of two examiners). The method was calibrated by a ZEBRIS ultrasound-based measuring method with WINSPINE software commercially available, and the measurement error rate of the method was determined by statistical calculations. On the basis of calibration and error calculations it could be established that the accuracy and the reproduci bility of the method were appropriate, because the maximum value of intraobserver variation is 0.97 degrees (18.8%), that of interobserver variation is 1.54 degrees (27.1%). A second way of verifying the method is to specify the difference between the angles determined by the two methods. The maximum value of the average difference is 1.62 degrees (26.6%)

KINEMATICAL ANALYSIS OF SHOULDER JOINT DURING ELEVATION MEASURED BY ULTRASOUND-BASED MEASURING SYSTEM

In order to analyse shoulder joint movements, the author uses a ZEBRIS CMS-HS ultrasound-based movement sensor and a related measurement program developed by the researchers in Biomechanical Laboratory in TUB. In essence, the measurement involves the determination of the spatial position of the 16 anatomical points specified on the basis of the coordinates of ultrasound-based triplets positioned on the upper limb, the scapula, and the thorax, measured in the course of motion. Kinematic characteristics of 74 shoulder joints of 50 healthy persons were identified during elevation. A specially developed processing program was used for the calculation and analysis of humerus elevation, scapulothoracal, and glenohumeral angles, defined as angles of spatial vectors; the glenohumeral, scapulothorocal and capuloglenoid ratio to be determined therefrom; and of scapulothoracal and glenohumeral rhythm during motion. Motion of the humerus and the scapula relative to each other was characterized by the rotation center of the two bones and rigid bodies as well as their absolute and relative displacement relative to each other. The biomechanical model of the shoulder joint during elevation can be described by analysing the results of the measurements performed

Foreword

DOI: 10.17489/biohun/2014/2/0

Application of OptiTrack motion capture systems in human movement analysis A systematic literature review

With the spreading of motion analysis decisions to invest into a new system demand scientific reference applications. The aim of the present systematic review is to reveal the biomechanical scientific applications of OptiTrack motion capture systems and to overview documented usage conditions and purposes. Six major scientific literature databases were used (PubMed, PubMed Central, ScienceDirect, IEEE Xplore, PLOS and Web Of Science). An OptiTrack camera system had to be used for human or biologically related motion capture. A total of 85 articles were included, 4 out of which dealt with the validation of OptiTrack systems and 81 utilized the system for biomechanical analyses. The data analysed and extracted from the system validation studies included: description of the validated and the reference system, measured features and observed errors. The data extracted from the utilizing studies also included: OptiTrack application, camera type and frequency, marker size, camera number, data processing software and the motion studied. The review offers a broad collection of biomechanical applications of OptiTrack motion capture systems as scientific references for certain motion studies. The review also summarizes findings on the accuracy of the systems. It concludes that the method descriptions of system usage are often underspecifie

Parameter Reduction in the Frequency Analysis of Center of Pressure in Stabilometry

During postural stability evaluation frequency analyses are applied on the motion of the foot center of pressure (CoP). In this study we compared the most widely used frequency type CoP parameters (median frequency, mean power frequency, bandwidth) including some newly defined parameters (frequency range power ratios, spectral power ratio between the anteroposterior and mediolateral directions, largest CoP amplitude with the corresponding frequency). The parameters were acquired from 25 young and healthy participants. Correlation analysis was used to exclude parameters that contain redundant information. Variance analysis was used to evaluate the behavior and usability of the parameters in different stance conditions (bipedal stance with eyes open and eyes closed, single leg stance with eyes open) where the balancing capability alters. Based on our results we recommend using the largest amplitude and frequency power ratios between specified frequency bands, spectral power ratio between anteroposterior and mediolateral direction and mean power frequency

Verification of simplified gait analysis

In this study we describe a simplified gait analysis system for the estimation of spatial-temporal parameters and kinetic parameters during walking on an instrumented treadmill. This method proposes to compute the values of temporal (length of double support phase, length of stance phase, time of step, time of stride) and few spatial parameters (step length, stride length, cadence) from the graph of time vs. ground reaction force at a constant gait speed. The method was verified by a clinical gait analysis method using a ZEBRIS ultrasound-based measuring system with ARMMODEL software, and the measurement error rate of the method was determined by statistical calculations. The maximum relative value of the average difference of temporal parameters is 0.79 % in cycle time and that of spatial parameters is 0.66%. On the basis of statistical analysis, it can be established that the measurement method is reproducible. This system is simple, inexpensive and does not provoke any discomfort to subjects. It can be car ried on for long periods of time during a treadmill walk, thus providing new longitudinal information such as the stride-to-stride variability of gait. Several clinical applications can be proposed such as outcome evaluation after different orthopaedical, rheumatological, neurological diseases, and monitoring of the rehabilitation process

Validation of the Estimated Torques of an Open-chain Kinematic Model of the Human Body

The standing human body is frequently modeled as an inverted double pendulum restricted to a single plane. In order to capture the coordination efforts and interplay between spatial dimensions, the model has to capture motion and joint torques in all spatial dimensions. Our two-segment model covers two degrees of freedom (ML and AP revolutions) at the ankle and the hip level and utilizes the Denavit-Hartenberg convention. This work aimed to validate the model's torque estimation on a diverse group of participants (11 women, 22–56 years, 11 men, 22–61 years). The inverse dynamic calculations provide estimated joint torques for a motion capture recorded trial, while standing on a force platform enables the indirect measurement of ankle torques. A 60-second-long visually guided balancing task was recorded and repeated three times. The estimated and the indirectly measured torques were compared, and offset and variance type errors ( normalized RMSE and R2 ) were analyzed. The R2-values were excellent (R2 > 0.90) 64 out of the 66 cases (97%) for AP torques and 58 out of the 66 cases (88%) for ML torques. Normalized RMSE values were dominantly under the 0.35 value with some outliers. RMSE showed no evident connection with age, body height, body mass, or BMI. An open-chain kinematic model with two segments, following the Denavit-Hartenberg convention, is well suited to estimate the control torque traces of the human body during standing balancing and needs only three tracked positions

Geometric and Mechanical Characterization of Human Carpal Bones – a Preliminary Study

Human hand injuries account for a significant number of accidents of young adults (mostly sports injuries) and elderly people. The most vulnerable part of the hand is the wrist, a construct consisting of numerous bones and ligaments. The hand is a complex structure, the mechanical behavior is hard to describe, and also it is sometimes hard to correctly diagnose the injuries. The goal of the present research is to create a quickly and inexpensive measurement method to characterize the geometrical and mechanical properties of carpal bones.The method presented is suitable to properly characterize the intact and damaged geometries of different carpal bones (capitate scaphoid, trapezium, pisiform). 3D models of intact and failed bones are determined by a 3D scanner, mechanical properties are determined with high-speed compression load (700 mm/min), which represents the fracture by falling down. According to the test results, the 3D scanning technique provided valuable geometrical data for cross-section calculation (scan before the test) and for analysis of the failure mode of the bones (scan after the test). The modulus of elasticity data for finite element simulation can be determined by the high-speed compression tests