Development of a Bimodal Ankle-Foot Prosthesis for Walking and Standing/Swaying

2013 ◽  
Vol 7 (3) ◽  
Author(s):  
Andrew H. Hansen ◽  
Eric A. Nickel
Keyword(s):  
Mechanical Properties ◽  
Lower Limb ◽  
Mechanical Stability ◽  
Balance Confidence ◽  
Prosthetic Foot ◽  
Human Ankle ◽  
Body Center ◽  
Impaired Balance ◽  
Prosthetic Feet ◽  
Lower Height

The human ankle-foot system conforms to a circular effective rocker shape for walking, but to a much flatter effective shape for standing and swaying. Many persons with lower limb amputations have impaired balance and reduced balance confidence, and may benefit from prostheses designed to provide flatter effective rocker shapes during standing and swaying tasks. This paper describes the development and testing of an ankle-foot prosthesis prototype that provides distinctly different mechanical properties for walking and standing/swaying. The prototype developed was a single-axis prosthetic foot with a lockable ankle for added stability during standing and swaying. The bimodal ankle-foot prosthesis prototype was tested on pseudoprostheses (walking boots with prosthetic feet beneath) for walking and standing/swaying loads, and was compared to an Otto Bock single-axis prosthetic foot and to able-bodied data collected in a previous study. The height-normalized radius of the effective rocker shape for walking with the bimodal ankle-foot prototype was equal to that found earlier for able-bodied persons (0.17); the standing and swaying effective shape had a lower height-normalized radius (0.70) compared with that previously found for able-bodied persons (1.11). The bimodal ankle-foot prosthesis prototype had a similar radius as the Otto Bock single-axis prosthetic foot for the effective rocker shape for walking (0.17 for both), but had a much larger radius for standing and swaying (0.70 for bimodal, 0.34 for single-axis). The results suggest that the bimodal ankle-foot prosthesis prototype provides two distinct modes, including a biomimetic effective rocker shape for walking and an inherently stable base for standing and swaying. The radius of the prototype's effective rocker shape for standing/swaying suggests that it may provide inherent mechanical stability to a prosthesis user, since the radius is larger than the typical body center of mass’s distance from the floor (between 50–60% of height). Future testing is warranted to determine if the bimodal ankle-foot prosthesis will increase balance and balance confidence in prosthesis users.

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.

Biomechanical Model Representing Energy Storing Prosthetic Feet

2010 ◽  
Author(s):  
Francy L. Sinatra ◽  
Stephanie L. Carey ◽  
Rajiv Dubey
Keyword(s):  
Motion Analysis ◽  
Lower Limb ◽  
Biomechanical Model ◽  
Body Segment ◽  
Prosthetic Foot ◽  
Biomechanical Models ◽  
Prosthetic Feet ◽  
Analysis System ◽  
Lower Limb Amputees ◽  
Metabolic Information

Previous studies have been conducted to develop a biomechanical model for a human’s lower limb. Amongst them, there have been several studies trying to quantify the kinetics and kinematics of lower-limb amputees through motion analysis [5, 10, 11]. Currently, there are various designs for lower-limb prosthetic feet such as the Solid Ankle Cushion Heel (SACH) from Otto Bock (Minneapolis) or the Flex Foot from Ossur (California). The latter is a prosthetic foot that allows for flexibility while walking and running. Special interest has been placed in recording the capabilities of these energy-storing prosthetic feet. This has been done through the creation of biomechanical models with motion analysis. In these previous studies the foot has been modeled as a single rigid-body segment, creating difficulties when trying to calculate the power dissipated by the foot [5, 20, 21]. This project studies prosthetic feet with energy-storing capabilities. The purpose is to develop an effective way of calculating power by using a biomechanical model. This was accomplished by collecting biomechanical data using an eight camera VICON (Colorado) motion analysis system including two AMTI (BP-400600, Massachusetts) force plates. The marker set that was used, models the foot using several segments, hence mimicking the motion the foot undergoes and potentially leading to greater accuracy. By developing this new marker set, it will be possible to combine the kinematic and kinetic profile gathered from it with previous studies that determined metabolic information. This information will allow for the better quantification and comparison of the energy storage and return (ES AR) feet and perhaps the development of new designs.

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.

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 THE INFLUENCE OF HYDRAULIC ANKLES AND MICROPROCESSOR-CONTROL ON THE BIOMECHANICS OF TRANS-TIBIAL AMPUTEES DURING QUIET STANDING ON A 5° SLOPE

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Michael McGrath ◽  
Katherine C. Davies ◽  
Piotr Laszczak ◽  
Beata Rek ◽  
Joe McCarthy ◽  
...  
Keyword(s):  
Lower Limb ◽  
Reaction Force ◽  
Quiet Standing ◽  
Microprocessor Control ◽  
Prosthetic Foot ◽  
Prosthetic Limbs ◽  
Ankle Joints ◽  
Sound Side ◽  
Computer Controlled ◽  
Prosthetic Feet

BACKGROUND: Lower limb amputees have a high incidence of comorbidities, such as osteoarthritis, which are believed to be caused by kinetic asymmetries. A lack of prosthetic adaptation to different terrains requires kinematic compensations, which may influence these asymmetries. METHOD: Six SIGAM grade E-F trans-tibial amputees (one bilateral) wore motion capture markers while standing on force plates, facing down a 5° slope. The participants were tested under three prosthetic conditions; a fixed attachment foot (FIX), a hydraulic ankle (HYD) and a microprocessor foot with a ‘standing support’ mode (MPF). The resultant ground reaction force (GRF) and support moment for prosthetic and sound limbs were chosen as outcome measures. These were compared between prosthetic conditions and to previously captured able-bodied control data. RESULTS: The distribution of GRF between sound and prosthetic limbs was not significantly affected by foot type. However, the MPF condition required fewer kinematic compensations, leading to a reduction in sound side support moment of 59% (p=0.001) and prosthetic side support moment of 43% (p=0.02) compared to FIX. For the bilateral participant, only the MPF positioned the GRF vector anterior to the knees, reducing the demand on the residual joints to maintain posture. CONCLUSION: For trans-tibial amputees, loading on lower limb joints is affected by prosthetic foot technology, due to the kinematic compensations required for slope adaptation. MPFs with ‘standing support’ might be considered reasonable and necessary for bilateral amputees, or amputees with stability problems due to the reduced biomechanical compensations evident. LAYMAN’S ABSTRACT: Lower limb prostheses work well on flat ground but often don’t adapt well to uneven ground or slopes. As a result, amputees tend to put more of their weight through their healthy leg. This can lead to problems like back pain and arthritis. In this study, the posture and weight distribution of below knee amputees were analysed while they stood facing down a slope. They did this with three different prosthetic feet; one with no ‘ankle’ joint, one with an ‘ankle’ (which could always move) and one with a computer-controlled ‘ankle’ (which could adapt to the slope but then resist movement when the wearer was stood still). Changing the prosthetic feet did not affect the amount of weight put through each limb, but when they had ‘ankle’ joints, the amputees were able to stand up straight, with a better posture. This meant that the demand on their joints was reduced, particularly on the healthy limb. One participant had below knee amputations on both legs. For this participant, only the computer-controlled device allowed her to stand up straight and well balanced. Article PDF Link: https://jps.library.utoronto.ca/index.php/cpoj/article/view/33517/25933 How to Cite: McGrath M, Davies KC, Laszczak P, Rek B, McCarthy J, Zahedi S, Moser D. The influence of hydraulic ankles and microprocessor-control on the biomechanics of trans-tibial amputees during quiet standing on a 5° slope. Canadian Prosthetics & Orthotics Journal. 2019;Volume2, Issue2, No.2. https://doi.org/10.33137/cpoj.v2i2.33517 CORRESPONDING AUTHOR Dr. Michael McGrath,Research Scientist–Clinical EvidenceBlatchford Group, Unit D Antura, Bond Close, Basingstoke, RG24 8PZ, United KingdomEmail: [email protected]: https://orcid.org/0000-0003-0195-970X  

scholarly journals Stiffness and energy storage characteristics of energy storage and return prosthetic feet

2019 ◽  
Vol 43 (3) ◽  
pp. 266-275 ◽  
Author(s):  
Nicholas D Womac ◽  
Richard R Neptune ◽  
Glenn K Klute
Keyword(s):  
Mechanical Properties ◽  
Energy Storage ◽  
Graphical User Interface ◽  
Lateral Loading ◽  
Prosthetic Foot ◽  
Limb Loading ◽  
Prosthetic Feet ◽  
Force Displacement ◽  
Storage Characteristics ◽  
Graphical User Interface Tool

Background: Mechanical properties of prosthetic feet can significantly influence amputee gait, but how they vary with respect to limb loading and orientation is infrequently reported. Objective: The objective of this study is to measure stiffness and energy storage characteristics of prosthetic feet across limb loading and a range of orientations experienced in typical gait. Study design: This study included mechanical testing. Methods: Force–displacement data were collected at combinations of 15 sagittal and 5 coronal orientations and used to calculate stiffness and energy storage across prosthetic feet, stiffness categories, and heel wedge conditions. Results: Stiffness and energy storage were highly non-linear in both the sagittal and coronal planes. Across all prosthetic feet, stiffness decreased with greater heel, forefoot, medial, and lateral orientations, while energy storage increased with forefoot, medial, and lateral loading orientations. Stiffness category was proportional to stiffness and inversely proportional to energy storage. Heel wedge effects were prosthetic foot dependent. Conclusion: Orientation, manufacturer, stiffness category, and heel wedge inclusion greatly influenced stiffness and energy storage characteristics. Clinical relevance These results and an available graphical user interface tool may help improve clinical prescriptions by providing prosthetists with quantitative measures to compare prosthetic feet.

scholarly journals Experimental characterization of the moment-angle curve during level and slope locomotion of transtibial amputee: Which parameters can be extracted to quantify the adaptations of microprocessor prosthetic ankle?

2021 ◽  
pp. 095441192110065
Author(s):  
Julie Davot ◽  
Marie Thomas-Pohl ◽  
Coralie Villa ◽  
Xavier Bonnet ◽  
Eric Lapeyre ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Lower Limb ◽  
Hydraulic Actuator ◽  
Period Range ◽  
Transtibial Amputation ◽  
Prosthetic Foot ◽  
Available Energy ◽  
Ankle Kinematics ◽  
Prosthetic Feet ◽  
The Moment

In case of transtibial amputation, the deficit resulting from the loss of the lower limb can be partly compensated with a prosthetic foot and adapted rehabilitation. New prosthetic feet have been developed for transtibial amputees to mimic ankle adaptability to varying terrain. Among them, Microprocessor Prosthetic Ankles (MPA) have a microprocessor to control an electric or a hydraulic actuator to adapt ankle kinematics in stairs and slopes. The objective is to investigate parameters extracted from the moment-angle curve (MAC) and use them to compare 3 MPA during level and slope locomotion against energy storing and return (ESR) foot. Five persons with lower limb transtibial amputation successively fitted with 3 MPA (Propriofoot™, Elan™, Meridium™) compared to their ESR foot. The participants had 2 weeks of adaptation before data acquisition and then a 3 week wash-out period. Range of motion, equilibrium point, hysteresis, late stance energy released, and quasi-stiffness were computed on level ground and 12% slope (upward and downward) thanks to the MAC at the ankle. The study shows the relevance of MAC parameters to evaluate the behavior of MPA. In particular, compared to ESR, all MPA tested in the present study demonstrated a better angle adaptation between walking conditions but a decrease of available energy for the propulsion. Among MPA, main results were: (i) for the Propriofoot™: an adaptation of the ankle angle without modification of the pattern of the MAC (ii) for the Elan™: a limited adaptation of the range of motion but a modification of the energy released (iii) for the Meridium™, the highest adaptation of the range of motion but the lowest available energy of propulsion. One of the main findings of the research is to show and quantify the relationship between range of motion and energy available when using different prosthetic feet in different walking conditions.

Prosthetic foot rollover shapes with implications for alignment of transtibial prostheses

2000 ◽  
Vol 24 (3) ◽  
pp. 205-215 ◽  
Author(s):  
A. H. Hansen ◽  
D. S. Childress ◽  
E. H. Knox
Keyword(s):  
Mechanical Properties ◽  
Dynamic Loading ◽  
Static Loading ◽  
Prosthetic Foot ◽  
Significant Characteristic ◽  
Dynamic Methods ◽  
Prosthetic Feet

Rollover shape is introduced as a significant characteristic of prosthetic feet. The rollover shapes of the Flexwalk, Quantum, SACH, and SAFE prosthetic feet were determined using three methods; two involving quasistatic loading and one dynamic loading. The results show that foot rollover shape properties obtained by quasistatic and by dynamic methods are similar.Relationships between foot rollover shape and the alignment of transtibial prostheses are introduced that suggest ways to align transtibial prostheses without walking trials and iterations. The relationships may explain what prosthetists attempt to accomplish when they dynamically align a transtibial limb. They also explain why prosthetic feet with different mechanical properties usually necessitate different alignments, and may explain why a number of gait studies of transtibial amputees do not show major gait differences when walking is executed on various kinds of prosthetic feet.

An analysis of the transport properties and mechanical stability of rapidly solidified Al-Sb alloy

2015 ◽  
Vol 10 (2) ◽  
pp. 2663-2681
Author(s):  
Rizk El- Sayed ◽  
Mustafa Kamal ◽  
Abu-Bakr El-Bediwi ◽  
Qutaiba Rasheed Solaiman
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Melt Spinning ◽  
Elastic Moduli ◽  
Mechanical Stability ◽  
Microstructural Analysis ◽  
Alloy System ◽  
Antimony Content ◽  
The Stability ◽  
Rapidly Solidified

The structure of a series of AlSb alloys prepared by melt spinning have been studied in the as melt–spun ribbons  as a function of antimony content .The stability  of these structures has  been  related to that of the transport and mechanical properties of the alloy ribbons. Microstructural analysis was performed and it was found that only Al and AlSb phases formed for different composition.  The electrical, thermal and the stability of the mechanical properties are related indirectly through the influence of the antimony content. The results are interpreted in terms of the phase change occurring to alloy system. Electrical resistivity, thermal conductivity, elastic moduli and the values of microhardness are found to be more sensitive than the internal friction to the phase changes. 

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