scholarly journals Effects on ankle power and sound limb load with an active prosthetic foot

2020 ◽  
Vol 6 (2) ◽  
Author(s):  
Eva Pröbsting ◽  
Björn Altenburg ◽  
Thomas Schmalz ◽  
Kerstin Krug
Keyword(s):  
Mechanical Work ◽  
Prosthetic Foot ◽  
Level Walking ◽  
Knee Loading ◽  
Sound Side ◽  
Strong Relation ◽  
Transfemoral Amputees ◽  
Prosthetic Feet ◽  
Power Outputs ◽  
Limb Load

AbstractThe performance of conventional prosthetic feet depends on material and construction principles. Certain powered feet can even generate net positive mechanical work in order to provide an active push-off. The aim of this study was to evaluate the influence of ankle power on the gait of transfemoral amputees. For this purpose level walking of six transfemoral amputees was analysed with a basic and an active foot and three different power settings of the latter. The results show clear advantages of the active foot in comparison with a basic foot. However, a strong relation of the sound side knee loading parameters with the varied ankle power outputs of the active foot couldn’t be shown.

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  

Characterizing adaptations of prosthetic feet in the frontal plane

2020 ◽  
Vol 44 (4) ◽  
pp. 225-233
Author(s):  
Michael Ernst ◽  
Björn Altenburg ◽  
Thomas Schmalz
Keyword(s):  
Energy Storage ◽  
Theoretical Model ◽  
Ankle Joint ◽  
Frontal Plane ◽  
Measured Data ◽  
Limb Amputation ◽  
Clinical Parameters ◽  
Mechanical Adaptation ◽  
Prosthetic Foot ◽  
Prosthetic Feet

Background: Energy-storage and return feet incorporate various design features including split toes. As a potential improvement, an energy-storage and return foot with a dedicated ankle joint was recently introduced allowing for easily accessible inversion/eversion movement. However, the adaptability of energy-storage and return feet to uneven ground and the effects on biomechanical and clinical parameters have not been investigated in detail. Objectives: To investigate the design-related ability of prosthetic feet to adapt to cross slopes and derive a theoretical model. Study design: Mechanical testing and characterization. Methods: Mechanical adaptation to cross slopes was investigated for six prosthetic feet measured by a motion capture system. A theoretical model linking the measured data with adaptations is proposed. Results: The type and degree of adaptation depends on the foot design, for example, stiffness, split toe or continuous carbon forefoot, and additional ankle joint. The model used shows high correlations with the measured data for all feet. Conclusions: The ability of prosthetic feet to adapt to uneven ground is design-dependent. The split-toe feet adapted better to cross slopes than those with continuous carbon forefeet. Joints enhance this further by allowing for additional inversion and eversion. The influence on biomechanical and clinical parameters should be assessed in future studies. Clinical relevance Knowing foot-specific ability to adapt to uneven ground may help in selecting an appropriate prosthetic foot for persons with a lower limb amputation. Faster and more comprehensive adaptations to uneven ground may lower the need for compensations and therefore increase user safety.

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.

Characteristics of sound side knee loading parameters of 53 trans-tibial amputees

2020 ◽  
Vol 81 ◽  
pp. 287-288
Author(s):  
E. Proebsting ◽  
M. Bellmann ◽  
T. Schmalz ◽  
A. Hahn
Keyword(s):  
Knee Loading ◽  
Sound Side

Influence of gait training and prosthetic foot category on external work symmetry during unilateral transtibial amputee gait

2013 ◽  
Vol 37 (5) ◽  
pp. 396-403 ◽  
Author(s):  
Vibhor Agrawal ◽  
Robert Gailey ◽  
Christopher O’Toole ◽  
Ignacio Gaunaurd ◽  
Adam Finnieston
Keyword(s):  
Repeated Measures ◽  
Gait Training ◽  
Third Party ◽  
External Work ◽  
Gait Dynamics ◽  
Prosthetic Foot ◽  
Negative Work ◽  
Level 3 ◽  
Prosthetic Feet ◽  
Level 2

Background:Prosthetic foot prescription guidelines lack scientific evidence and are concurrent with an amputee’s concurrent with an amputee’s Medicare Functional Classification Level (K-Level) and categorization of prosthetic feet.Objective:To evaluate the influence of gait training and four categories of prosthetic feet (K1, K2, K3, and microprocessor ankle/foot) on Symmetry in External Work for K-Level-2 and K-Level-3 unilateral transtibial amputees.Design:Randomized repeated-measures trial.Methods:Five K-Level-2 and five K-Level-3 subjects were tested in their existing prosthesis during Session 1 and again in Session 2, following 2 weeks of standardized gait training. In Sessions 3–6, subjects were tested using a study socket and one of four randomized test feet. There was an accommodation period of 10–14 days with each foot. Symmetry in External Work for positive and negative work was calculated at each session to determine symmetry of gait dynamics between limbs at self-selected walking speeds.Results:K-Level-2 subjects had significantly higher negative work symmetry with the K3 foot, compared to K1/K2 feet. For both subject groups, gait training had a greater impact on positive work symmetry than test feet.Conclusion:Higher work symmetry is possible for K-Level-2 amputees who are trained to take advantage of K3 prosthetic feet designs. There exists a need for an objective determinant for categorizing and prescribing prosthetic feet.Clinical relevanceFindings that gait training can influence symmetry of gait dynamics and that K-Level-2 amputees can achieve greater work symmetry with a K3 foot having a “J-shaped” ankle and heel-to-toe footplate could potentially impact prosthetic care and foot prescription by clinicians and reimbursement guidelines by third-party health-care payers.

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.

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.

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