Recommended number of strides for automatic assessment of gait symmetry and regularity in above-knee amputees by means of accelerometry and autocorrelation analysis (original) (raw)
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Repeatability of kinetic and kinematic measurements in gait studies of the lower limb amputee
Prosthetics and orthotics international, 1987
During the last few years considerable attention has been given to the use of gait analysis as a tool for clinical use. The instrumentation for measurement of the kinetics and kinematics of human locomotion was originally designed for research use. Extension of its use into the clinical field calls for simplified methodology and clearly defined protocols with precise identification of the relevant parameters for the analysis. Force platforms, TV-computer and pylon transducer systems were used for collection of kinetic and kinematic data of five normal subjects, 10 below-knee, 10 above-knee and one hip disarticulation amputee. The repeatability tests showed significant differences in the measured parameters. These variations are attributed to the methodology of the analysis and the step to step variation of the subjects' gait. Differences in the degree of step to step variation between various amputee and normal subjects are quantified. In this presentation the capability of pres...
Symmetry function – An effective tool for evaluating the gait symmetry of trans-femoral amputees
Gait & Posture, 2021
Background: Prostheses can help persons with trans-femoral amputation (TFA) regain normal function, but such individuals still exhibit gait deviations expressed in gait asymmetries. We apply a specialised tool, the Symmetry Function (SF), to evaluate the symmetry of walking in terms of kinematic and dynamic variables and to identify areas with large side deviations (exceeding defined ±5% threshold) in the movement cycle. Research question: Which movements and joints or GRF components revealed the most significant side deviations in the movement cycle? When exactly are they located in the gate cycle? Methods: In this retrospective observational study, an instrumented motion analysis system was used to register the gait of fourteen patients after unilateral TFA. Measurements involved evaluating the time series of gait variables characterising a range of motion and the ground reaction force components. Comparison of the prosthetic (involved) limb with the sound (uninvolved) limb in TFA patients was carried out on the basis of the Symmetry Function values. Results: The Symmetry Function proved to be an effective tool to localise the regions of asymmetry and limb dominance in the full gait cycle. The difference between sides revealed by the Symmetry Function was the highest for the pelvis and the hip. In the sagittal plane, the pelvis was asymmetrically tilted, reaching the highest SF value of more than 25 % at 60 % cycle time. In the transverse plane, the pelvis was even more asymmetrically positioned throughout the entire gait cycle (50 % difference). The hip in the frontal plane reached a 60 % difference throughout the single support phase for the involved and then for the uninvolved limb. Significance: The Symmetry Function allows for the detection of gait asymmetries, temporal shifts in the gait phases and may assess the precise in time adaptation of prostheses and rehabilitation monitoring, especially in unilateral impairments.
Variability and stability analysis of walking of transfemoral amputees
Medical Engineering & Physics, 2010
Variability and stability of walking of eight transfemoral amputees and eight healthy controls was studied under four conditions: walking inside on a smooth terrain, walking while performing a dual-task and walking outside on (ir)regular surfaces. Trunk accelerations were recorded with a tri-axial accelerometer. Walking speed, mean and coefficient of variation of stride times (ST) and the root mean squares (RMS) of trunk accelerations was calculated. Gait variability and stability were quantified using measures derived from the theory of stochastic dynamics. Regularity was indexed using the sample entropy (SEn) and the scaling exponent˛derived form Detrended Fluctuations Analysis. Local stability (LSE) quantified gait stability.
Clinical Biomechanics, 2020
Background: People with lower limb amputation often walk with asymmetrical gait patterns potentially leading to long-term health problems, ultimately affecting their quality of life. The ability to discreetly detect and quantify the movement of bilateral thighs and shanks using wearable sensor technology can provide additional insight into how a person walks with a lower limb prosthesis. This study investigated segmental symmetry and segmental repeatability of people with unilateral lower limb amputation, examining performance of the prosthetic and intact limbs. Methods: Gyroscope signals were recorded from four inertial measurement units worn on bilateral lower limb segments of subjects with unilateral lower limb amputation during the 10-m walk test. Raw angular velocity signals were processed using dynamic time warping and application of algorithms resulting in symmetry measures comparing similarity of prosthetic to intact limb strides, and repeatability measures comparing movement of one limb to its consecutive strides. Findings: Biomechanical differences in performance of the prosthetic and intact limb segments were detected with the segmental symmetry and segmental repeatability measures in 128 subjects. More asymmetries and less consistent movements of the lower limbs were exhibited by subjects with transfemoral amputation versus transtibial amputation (p < .004, Cohen's d = 0.65-1.1). Interpretation: Sensor-based measures of segmental symmetry and segmental repeatability were found to be reliable in detecting discreet differences in movement of the prosthetic versus intact lower limbs in amputee subjects. These measures provide a convenient tool for enhanced prosthetic gait analysis with the potential to focus rehabilitative and prosthetic interventions.
Journal of NeuroEngineering and Rehabilitation
Background: The literature suggests that optimal levels of gait symmetry might exist for lower-limb amputees. Not only these optimal values are unknown, but we also don't know typical symmetry ratios or which measures of symmetry are essential. Focusing on the symmetries of stance, step, first peak and impulse of the ground reaction force, the aim of this work was to answer to three methodological and three clinical questions. The methodological questions wanted to establish a minimum set of symmetry indexes to study and if there are limitations in their calculations. The clinical questions wanted to establish if typical levels of temporal and loading symmetry exist, and change with the level of amputation and prosthetic components. Methods: Sixty traumatic, K3-K4 amputees were involved in the study: 12 transfemoral mechanical knee users (TFM), 25 C-leg knee users (TFC), and 23 transtibial amputees (TT). Ninety-two percent used the Ossur Variflex foot. Ten healthy subjects were also included. Ground reaction force from both feet were collected with the Novel Pedar-X. Symmetry indexes were calculated and statistically compared with regression analyses and non-parametric analysis of variance among subjects. Results: Stance symmetry can be reported instead of step, but it cannot substitute impulse and first peak symmetry. The first peak cannot always be detected on all amputees. Statistically significant differences exist for stance symmetry among all groups, for impulse symmetry between TFM and TFC/TT, for first peak symmetry between transfemoral amputees altogether and TT. Regarding impulse symmetry, 25% of TFC and 43% of TT had a higher impulse on the prosthetic side. Regarding first peak symmetry, 59% of TF and 30% of TT loaded more the prosthetic side. Conclusions: Typical levels of symmetry for stance, impulse and first peak change with the level of amputation and componentry. Indications exist that C-leg and energy-storage-and-return feet can improve symmetry. Results are suggestive of two mechanisms related to sound side knee osteoarthritis: increased impulse for TF and increased first peak for TT. These results can be useful in clinics to set rehabilitation targets, understand the advancements of a patient during gait retraining, compare and chose components and possibly rehabilitation programs.
Journal of Rehabilitation Research and Development, 2014
Analysis of upper-body accelerations is a promising and simple technique for quantitatively assessing some general features of gait such as stability, harmony, and symmetry. Despite the growing literature on elderly healthy populations and neurological patients, few studies have used accelerometry to investigate these features in subjects with lower-limb amputation. We enrolled four groups of subjects: subjects with transfemoral amputation who walked with a locked knee prosthesis, subjects with transfemoral amputation who walked with an unlocked knee prosthesis, subjects with transtibial amputation, and age-matched nondisabled subjects. We found statistically significant differences for stability (p < 0.001), harmony (p < 0.001), and symmetry (p < 0.001) of walking, with general trends following the noted order of subjects, but with the lowest laterolateral harmony in subjects with transtibial amputation. This study is the first to investigate upper-body acceleration of subjects with unilateral lower-limb amputation during walking who were evaluated upon dismissal from a rehabilitation hospital; it is also the first study to differentiate the sample in terms of level of amputation and type of prosthesis used.
Symmetry function as a new tool for evaluating the symmetry of gait in transfemoral amputees
2020
Background: Numerous studies have demonstrated signi cant asymmetries in unilateral amputee gait. The underlying dissimilarities between prosthetic and intact limbs have not yet been widely examined. To gain more insight into the functionality of asymmetries, we propose a new tool, the symmetry function (SF), to evaluate the symmetry of walking in terms of kinematic and dynamic variables of patients after unilateral transfemoral amputation and to identify areas with the largest side deviations in the movement cycle. Methods: An instrumented motion analysis system was used to register the gait of fourteen patients after unilateral trans-femoral amputation (TFA). Measurements involved evaluating the time series of gait variables characterizing a range of motion and the time series of the ground reaction force components. Comparison of the involved limb with the uninvolved limb in TFA patients was carried out on the basis of the SF values. Results: The symmetry function proved to be an excellent tool to localize the regions of asymmetry and their positive or negative directions in the full gait cycle. The difference between sides revealed by the symmetry function was the highest for the pelvis and the hip. In the sagittal plane, the pelvis was asymmetrically tilted, reaching the highest SF value of more than 25% at 60% cycle time. In the transverse plane, the pelvis was even more asymmetrically positioned throughout the entire gait cycle (50% difference on average). The hip in the frontal plane reached a 60% difference in SF throughout the single support phase for the prosthetic and then for the intact limb. Conclusions: The symmetry function allows for the detection of gait asymmetries and shifts in the center of gravity and may assess the precise in time adaptation of prostheses and rehabilitation monitoring, especially in unilateral impairments. Trial registration: The trial registration number (TRN): 379991 issued by the Australian New Zealand Clinical Trials Registry (ANZCTR) on 07.05.2020 (retrospectively registered).