Dynamic Characteristics of Stance Phase Gait with Prosthetic Foot for Trans-Tibial Amputee

2011 ◽  
Author(s):  
Hyeon-Seok Cho ◽  
Gyoo-Suk Kim ◽  
Sung-Jae Kang ◽  
Jei-Chung Ryu ◽  
Mu-Sung Mun
Keyword(s):  
Dynamic Characteristics ◽  
Stance Phase ◽  
Prosthetic Foot

Parametric Evaluation of Hindfoot and Forefoot Properties and Their Effect on the Angular Stiffness of Prosthetic Feet

2012 ◽  
Author(s):  
Peter G. Adamczyk ◽  
Michelle Roland ◽  
Michael E. Hahn
Keyword(s):  
Stance Phase ◽  
Direct Calculation ◽  
Future Studies ◽  
Prosthetic Foot ◽  
Moment Arms ◽  
Walking Performance ◽  
Deformation Mechanics ◽  
Prosthetic Feet ◽  
Stiffness Characteristics ◽  
Parametric Adjustment

Prosthetic foot stiffness has been recognized as an important factor in optimizing the walking performance of amputees [1–3]. Commercial feet are available in a range of stiffness categories and geometries. The stiffness of linear displacements of the hindfoot and forefoot for several commercially available feet have been reported to be within a range of 27–68 N/mm [4] and 28–76 N/mm [5], respectively, but these values are most relevant only to the earliest and latest portions of stance phase, when linear compression or rebound naturally occur. In contrast, mid-stance kinetics are more related to the angular stiffness of the foot, which describes the ankle torque produced by angular progression of the lower limb over the foot during this phase. Little data is available regarding the angular stiffness of any commercially available feet. The variety of geometries between manufacturers and models of prosthetic feet makes a direct calculation of effective angular stiffness challenging due to changes in moment arms based on loading condition, intricacies of deformation mechanics of the structural components, and mechanical interaction between hindfoot and forefoot components. Thus, modeling the interaction between hindfoot stiffness, forefoot stiffness, and keel geometries and their combined effect on the angular stiffness of the foot may be a useful tool for correlating functional outcomes with stiffness characteristics of various feet. To understand how each of these factors affects angular stiffness, we developed a foot that can parametrically adjust each of these factors independently. The objective of this study was to mathematically model, design, and experimentally validate a prosthetic foot that has independent hindfoot and forefoot components, allowing for parametric adjustment of stiffness characteristics and keel geometry in future studies of amputee gait.

scholarly journals Development of a Mechatronic Platform and Validation of Methods for Estimating Ankle Stiffness During the Stance Phase of Walking

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Elliott J. Rouse ◽  
Levi J. Hargrove ◽  
Eric J. Perreault ◽  
Michael A. Peshkin ◽  
Todd A. Kuiken
Keyword(s):  
Mechanical Properties ◽  
Stance Phase ◽  
Testing Machine ◽  
Human Interaction ◽  
Joint Torque ◽  
Average Error ◽  
Prosthetic Foot ◽  
Ankle Impedance ◽  
Ankle Stiffness ◽  
Human Ankle

The mechanical properties of human joints (i.e., impedance) are constantly modulated to precisely govern human interaction with the environment. The estimation of these properties requires the displacement of the joint from its intended motion and a subsequent analysis to determine the relationship between the imposed perturbation and the resultant joint torque. There has been much investigation into the estimation of upper-extremity joint impedance during dynamic activities, yet the estimation of ankle impedance during walking has remained a challenge. This estimation is important for understanding how the mechanical properties of the human ankle are modulated during locomotion, and how those properties can be replicated in artificial prostheses designed to restore natural movement control. Here, we introduce a mechatronic platform designed to address the challenge of estimating the stiffness component of ankle impedance during walking, where stiffness denotes the static component of impedance. The system consists of a single degree of freedom mechatronic platform that is capable of perturbing the ankle during the stance phase of walking and measuring the response torque. Additionally, we estimate the platform's intrinsic inertial impedance using parallel linear filters and present a set of methods for estimating the impedance of the ankle from walking data. The methods were validated by comparing the experimentally determined estimates for the stiffness of a prosthetic foot to those measured from an independent testing machine. The parallel filters accurately estimated the mechatronic platform's inertial impedance, accounting for 96% of the variance, when averaged across channels and trials. Furthermore, our measurement system was found to yield reliable estimates of stiffness, which had an average error of only 5.4% (standard deviation: 0.7%) when measured at three time points within the stance phase of locomotion, and compared to the independently determined stiffness values of the prosthetic foot. The mechatronic system and methods proposed in this study are capable of accurately estimating ankle stiffness during the foot-flat region of stance phase. Future work will focus on the implementation of this validated system in estimating human ankle impedance during the stance phase of walking.

Effect of Walking Speed on Angular Stiffness and Roll-Over Shape of the Intact and Prosthetic Feet of Transtibial Amputees

2013 ◽  
Author(s):  
Michelle Roland ◽  
Peter G. Adamczyk ◽  
Michael E. Hahn
Keyword(s):  
Lower Limb ◽  
Stance Phase ◽  
Walking Speed ◽  
Plantar Flexor ◽  
Limb Function ◽  
Prosthetic Foot ◽  
Material Stiffness ◽  
Prosthetic Feet ◽  
Transtibial Amputees ◽  
Lower Limb Function

The calculated roll-over shape and respective radius of intact and prosthetic feet has been shown to be a useful measure of lower limb function during walking [1–2]. Hansen et al [3] reported that the roll-over radius, R, is constant over a range of speeds for the intact foot-ankle system. It may be assumed that the prosthetic foot R would also be constant with increased walking speed. Similarly, the angular stiffness of prosthetic feet is not likely to change with walking speed, as the material stiffness remains unchanged. However, the effective angular stiffness of the intact ankle may increase with the plantar flexor moment during the stance phase of gait, which typically increases in magnitude with walking speed.

scholarly journals Development of Instrumented Running Prosthetic Feet for the Collection of Track Loads on Elite Athletes

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5758
Author(s):  
Nicola Petrone ◽  
Gianfabio Costa ◽  
Gianmario Foscan ◽  
Antonio Gri ◽  
Leonardo Mazzanti ◽  
...  
Keyword(s):  
Data Collection ◽  
Stance Phase ◽  
Elite Athletes ◽  
Calibration Procedure ◽  
Base Station ◽  
Ground Reaction Forces ◽  
Prosthetic Foot ◽  
Biomechanical Modelling ◽  
Reaction Forces ◽  
Prosthetic Feet

Knowledge of loads acting on running specific prostheses (RSP), and in particular on running prosthetic feet (RPF), is crucial for evaluating athletes’ technique, designing safe feet, and biomechanical modelling. The aim of this work was to develop a J-shaped and a C-shaped wearable instrumented running prosthetic foot (iRPF) starting from commercial RPF, suitable for load data collection on the track. The sensing elements are strain gauge bridges mounted on the foot in a configuration that allows decoupling loads parallel and normal to the socket-foot clamp during the stance phase. The system records data on lightweight athlete-worn loggers and transmits them via Wi-Fi to a base station for real-time monitoring. iRPF calibration procedure and static and dynamic validation of predicted ground-reaction forces against those measured by a force platform embedded in the track are reported. The potential application of this wearable system in estimating determinants of sprint performance is presented.

A Single Leg Model With a Novel Variable Stiffness Element Based on the Dynamics Analysis and its Dynamic Characteristics

2017 ◽  
Author(s):  
Zhang Li ◽  
Yuegang Tan ◽  
Liu Hong ◽  
Jaspreet Singh Dhupia ◽  
Shun Zeng ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Stance Phase ◽  
Variable Stiffness ◽  
Body Motion ◽  
Dynamics Analysis ◽  
Variable Sensitivity ◽  
Variation Characteristics ◽  
Reaction Forces ◽  
Independent Variable ◽  
Vibration Parameters

This paper presents a bio-inspired dynamic leg model with a novel variable stiffness element to create a normal body motion during stance phase. The variable stiffness in the model is implemented through structure-controlled stiffness. It allows to decouple the stiffness from joint motion, which makes the stiffness a independent variable. Sensitivity of leg model to the variable stiffness element is investigated through dynamics analysis. Because of the decoupled structure of dynamics equations, the deflection of ankle joint related to variable stiffness element is planned based on generalized forced vibration motion in order to create the leg’s motion. A detailed study to investigate the dynamic characteristics under different generalized vibration parameters, and the desired variable stiffness function are evaluated. It is found that under the effects of variable stiffness, the ground reaction forces of leg model during stance motion have similar characteristics to those observed for mammals. Furthermore, in order to create a normal motion during stance phase, linear stiffness variation characteristics and small stiffness range are needed for the proposed variable stiffness actuator.

The effects of common footwear on stance-phase mechanical properties of the prosthetic foot-shoe system

2017 ◽  
Vol 42 (2) ◽  
pp. 198-207 ◽  
Author(s):  
Matthew J Major ◽  
Joel Scham ◽  
Michael Orendurff
Keyword(s):  
Mechanical Properties ◽  
Repeated Measures ◽  
Clinical Relevance ◽  
Stance Phase ◽  
Mechanical Characteristics ◽  
Mechanical Characterization ◽  
Test Machine ◽  
Mechanical Function ◽  
Prosthetic Foot ◽  
Prosthetic Feet

Background:Prosthetic feet are prescribed based on their mechanical function and user functional level. Subtle changes to the stiffness and hysteresis of heel, midfoot, and forefoot regions can influence the dynamics and economy of gait in prosthesis users. However, the user’s choice of shoes may alter the prosthetic foot-shoe system mechanical characteristics, compromising carefully prescribed and rigorously engineered performance of feet.Objectives:Observe the effects of footwear on the mechanical properties of the prosthetic foot-shoe system including commonly prescribed prosthetic feet.Study design:Repeated-measures, Mechanical characterization.Methods:The stiffness and energy return was measured using a hydraulic-driven materials test machine across combinations of five prosthetic feet and four common shoes as well as a barefoot condition.Results:Heel energy return decreased by an average 4%–9% across feet in all shoes compared to barefoot, with a cushioned trainer displaying the greatest effect. Foot designs that may improve perceived stability by providing low heel stiffness and rapid foot-flat were compromised by the addition of shoes.Conclusion:Shoes altered prosthesis mechanical characteristics in the sagittal and frontal planes, suggesting that shoe type should be controlled or reported in research comparing prostheses. Understanding of how different shoes could alter certain gait-related characteristics of prostheses may aid decisions on footwear made by clinicians and prosthesis users.Clinical relevanceShoes can alter function of the prosthetic foot-shoe system in unexpected and sometimes undesirable ways, often causing similar behavior across setups despite differences in foot design, and prescribing clinicians should carefully consider these effects on prosthesis performance.

scholarly journals Analysis of Rollover Shape and Energy Storage and Return in Cantilever Beam-Type Prosthetic Feet

2014 ◽  
Author(s):  
Kathryn M. Olesnavage ◽  
Amos G. Winter
Keyword(s):  
Energy Storage ◽  
Cantilever Beam ◽  
Cross Section ◽  
Stance Phase ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Heel Strike ◽  
Prosthetic Foot ◽  
Beam Type ◽  
Prosthetic Feet

This paper presents an analysis of the rollover shape and energy storage and return in a prosthetic foot made from a compliant cantilevered beam. The rollover shape of a prosthetic foot is defined as the path of the center of pressure along the bottom of the foot during stance phase of gait, from heel strike to toe off. This path is rotated into the reference frame of the ankle-knee segment of the leg, which is held fixed. In order to achieve correct limb loading and gait kinematics, it is important that a prosthetic foot both mimic the physiological rollover shape and maximize energy storage and return. The majority of prosthetic feet available on the market are cantilever beam-type feet that emulate ankle dorsiflexion through beam bending. In this study, we show analytically that a prosthetic foot consisting of a beam with constant or monotonically decreasing cross-section cannot replicate physiological rollover shape; the foot is either too stiff when the ground reaction force (GRF) acts near the ankle, or too compliant when the GRF acts near the toe. A rigid constraint is required to prevent the foot from over-deflecting. Using finite element analysis (FEA), we investigated how closely a cantilever beam with constrained maximum deflection could mimic physiological rollover shape and energy storage/return during stance phase. A constrained beam with constant cross-section is able to replicate physiological rollover shape with R2 = 0.86. The ratio of the strain energy stored and returned by the beam compared to the ideal energy storage and return is 0.504. This paper determines that there is a trade off between rollover shape and energy storage and return in cantilever beam-type prosthetic feet. The method and results presented in this paper demonstrate a useful tool in early stage prosthetic foot design that can be used to predict the rollover shape and energy storage of any type of prosthetic foot.

scholarly journals Balance in lower limb child amputees

1981 ◽  
Vol 5 (1) ◽  
pp. 11-18 ◽  
Author(s):  
L. A. Clark ◽  
R. F. Zernicke
Keyword(s):  
Upper Limb ◽  
Lower Limb ◽  
Postural Stability ◽  
Stance Phase ◽  
Heel Strike ◽  
Proprioceptive Information ◽  
Knee Stability ◽  
Centre Of Pressure ◽  
Prosthetic Foot ◽  
Base Of Support

Postural stability of five unilateral above-knee amputee children was measured when wearing the SACH and the experimental Child Amputee Prosthetic Project (CAPP) prosthetic foot. Excursions of the centre of pressure of the supportive forces were recorded via force platform during sustained weight-shifting forward, backward, left, right, and during normal standing. Visual proprioception effects on upright stance were also demonstrated with these child amputees. Total base of support did not differ for the two types of prosthetic feet, but the functional base of support for SACH foot was significantly larger than CAPP. Fluctuations of centre of pressure about a mean position in normal standing were less when children used CAPP foot. Focusing on a static target had no effect on postural stability in either anterior-posterior or lateral direction for CAPP foot conditions, but lack of visual target had a deleterious effect on lateral stability when SACH foot was worn. Balance is one of the most difficult problems for a lower limb amputee (Hellebrandt et al, 1950; Moncur, 1969; Murdoch, 1969). The absence of part or all of a lower limb reduces the amount of proprioceptive information about the surfaces on which the foot is resting and the precise location of the prosthetic limb. While limited data have been reported on the balance and stability characteristics of adult amputees (Fernie and Holliday, 1978; Hellebrandt et al, 1950), information about balance of child amputees is almost non-existent. We have found only one report of the postural stability characteristics of a child amputee; Shambes and Waterland (1970) studied an 11-year-old quadrilateral amputee who had congenital Lisfranc amputations of both lower limbs, long above-elbow amputation of the left upper limb, and medium below-elbow amputation of the right upper limb. The purpose of this study was to detail the postural stability characteristics for lower limb child amputees. In addition, the conventional SACH prosthetic foot was compared with the experimental Child Amputee Prosthetic Project (CAPP) foot for various postural tasks. The SACH foot (Fig. la) is usually constructed with a moulded polyurethane material which incorporates a heel cushion to allow some compression of the heel during heel strike in walking to simulate plantar flexion of a normal foot. The CAPP foot (Fig. lb) is an experimental prosthesis undergoing development at the UCLA Child Amputee Prosthetic Project. It is designed to provide more knee stability during early stance phase during walking and also to respond to torsional loads occurring in the stance phase of walking. The heel projection of the CAPP foot is non-weight bearing and deflects upward at heelstrike. With the ground reaction forces shifted more anteriorly on the supporting foot there is an expected increase in dynamic knee stability during the stance phase of walking. While additional research is being conducted on the dynamic characteristics of the CAPP foot, the present study provides some preliminary information about the postural stability of child amputees using the experimental CAPP foot, as well as providing a comparison with the conventional SACH foot.

scholarly journals Alignment of the above-knee prosthesis

1979 ◽  
Vol 3 (3) ◽  
pp. 137-139 ◽  
Author(s):  
J. Foort
Keyword(s):  
Stride Length ◽  
Stance Phase ◽  
Knee Prosthesis ◽  
Weight Bearing ◽  
Voluntary Control ◽  
Normal Side ◽  
Prosthetic Foot ◽  
Heel Contact ◽  
Hip Abduction ◽  
Save Energy

1. A long prosthesis forces drop of the pelvis on the normal side, can cause crotch pressure and distal femoral pressure leading to discomfort, can reduce voluntary control, may force the amputee to walk with an abducted stump hip for stance phase and to swing the leg outward for toe clearance in swing phase or to compensate by rising up on the sound foot to clear the prosthetic foot. 2. A short prosthesis may shorten stride, increase listing over the prosthesis in stance phase, enhance prospects for a narrow, walking base and increase the ease of balancing o ver the prosthesis in stance phase. 3. Moving the foot forward relative to the stump increases prosthetic stride length. 4. Moving the foot posteriorly relative to the stump does the reverse. 5. Displacing the foot medially has variable effects which may include walking with a narrow base, moving the foot laterally by hip abduction of the stump for relief of pain and increased voluntary control. Stump length and strength is a strong mediator in what choice the amputee makes as he tries to get comfort, save energy and maintain a cosmetic gait. 6. Displacing the foot laterally may lead to the amputee adducting the stump to reduce the width of the walking base, or force him to lean over the prosthesis during stance phase an it, or lift his body over the prosthesis by means of a strong lateral impulse from the sound leg as the prosthesis becomes weight-bearing with the torso erect. 7. Increasing downward inclination of the prosthetic toe shortens stride on the normal side. 8. Tilting the toe upward on the prosthetic side lengthens stride on the normal side. 9. Knee axis stability is increased for a larger percentage of the stance phase on the prosthesis when the prosthetic toe is inclined — downward or when the prosthetic foot is moved forward with respect to the stump. 10. Toe-in and toe-out have comparable effects to moving the foot inward or outward except that the effects are lessened or reversed at heel contact, tending toward the effects indicated as the step advances. 12. Inversion-eversion changes are basically for cosmetic effects.

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