Effects of joint alignment and type on mechanical properties of thermoplastic articulated ankle-foot orthosis

2011 ◽  
Vol 35 (2) ◽  
pp. 181-189 ◽  
Author(s):  
Fan Gao ◽  
William Carlton ◽  
Susan Kapp
Keyword(s):  
Mechanical Properties ◽  
Ankle Joint ◽  
Plantar Flexion ◽  
Skin Irritation ◽  
Neutral Position ◽  
Motor Shaft ◽  
Ankle Foot Orthosis ◽  
Resistance Torque ◽  
Flexure Joints ◽  
Foot Orthosis

Background: Articulated or hinged ankle-foot orthosis (AFO) allow more range of motion. However, quantitative investigation on articulated AFO is still sparse.Objective: The objective of the study was to quantitatively investigate effects of alignment and joint types on mechanical properties of the thermoplastic articulated AFO.Study design: Tamarack dorsiflexion assist flexure joints with three durometers (75, 85 and 95) and free motion joint were tested. The AFO joint was aligned with the center of the motor shaft (surrogate ankle joint), 10 mm superior, inferior, anterior and posterior with respect to the motor shaft center.Methods: The AFO was passively moved from 20° plantar flexion to 15° dorsiflexion at a speed of 10°/s using a motorized device. Mechanical properties including index of hysteresis, passive resistance torque and quasi-static stiffness (at neutral, 5°, 10° and 15° in plantar flexion) were quantified.Results: Significant effects of joint types and joint alignment on the mechanical properties of an articulated thermoplastic AFO were revealed. Specifically, center alignment showed minimum resistance and stiffness while anterior and posterior alignment showed significantly higher resistance and stiffness. The dorsiflexion assist torques at neutral position ranged from 0.69 ± 0.09 to 1.88 ± 0.10 Nm.Conclusions: Anterior and posterior alignment should be avoided as much as possible.Clinical relevanceThe current study suggested that anterior and posterior alignment be avoided as much as possible in clinical practice due to potential skin irritation and increase in stress around the ankle joint.

scholarly journals Development of an ankle – foot orthosis with an oil damper

2005 ◽  
Vol 29 (3) ◽  
pp. 209-219 ◽  
Author(s):  
S. Yamamoto ◽  
A. Hagiwara ◽  
T. Mizobe ◽  
O. Yokoyama ◽  
T. Yasui
Keyword(s):  
Mechanical Properties ◽  
Ankle Joint ◽  
Essential Feature ◽  
Plantar Flexion ◽  
Eccentric Contraction ◽  
Assistive Device ◽  
Hip Joints ◽  
Ankle Foot Orthosis ◽  
Paretic Side ◽  
Foot Orthosis

The purpose of the present study was to develop an ankle – foot orthosis (AFO) that satisfies the requirements for an AFO for patients with hemiplegia as determined in a previous study. An oil damper has been introduced as an assistive device. The oil damper provides a resistive moment to plantar flexion of the ankle joint during initial stance on the paretic side. This function improves the insufficient eccentric contraction of the dorsiflexors. The magnitude of the resistive moment generated by this newly developed AFO can be changed easily to adjust its properties in accordance with the requirements of each patient. The mechanical properties of the AFO were measured, and the results showed that the AFO generated a sufficient resistive moment. Hemiplegic gaits with various types of AFOs were assessed, and it was found that the properties of the AFO affected the movements of the ankle, the knee, and the hip joints. The effects of the resistive moment on the alignment of the shank to the floor during initial stance are also discussed. Based on the results of this study, it is concluded that adjustability will be an essential feature for future AFOs.

scholarly journals A Model to Predict the Effect of Ankle Joint Misalignment on Calf Band Movement in Ankle-Foot Orthoses

2007 ◽  
Vol 31 (1) ◽  
pp. 76-87 ◽  
Author(s):  
Stefania Fatone ◽  
Andrew H. Hansen
Keyword(s):  
Ankle Joint ◽  
Walking Speed ◽  
Sagittal Plane ◽  
Plantar Flexion ◽  
Dimensional Model ◽  
Ankle Foot Orthosis ◽  
Ankle Joints ◽  
Ankle Foot Orthoses ◽  
Foot Orthosis ◽  
Anterior Posterior

Accurate alignment of anatomical and mechanical joint axes is one of the major biomechanical principles pertaining to articulated orthoses, yet knowledge of the potential effects of axis misalignment is limited. The purpose of this project was to model the effects of systematic linear (proximal-distal and anterior-posterior) misalignments of single axis mechanical ankle joints in an ankle-foot orthosis (AFO) in order to determine the degree and direction of calf band travel that would occur over a functional range of motion. Sagittal plane misalignments of the ankle joint centres of an AFO were simulated using a simple two-dimensional model for both a range of ankle angles and a typical able-bodied ankle kinematic curve for self-selected normal walking speed. The model assumed that no movement occurred between the foot and the foot-plate of the AFO. The model predicted that for anterior (positive horizontal) misalignments, dorsiflexion movements would cause the calf band to travel proximally (i.e., up the leg) and plantar flexion movements would cause the calf band to travel distally (i.e., down the leg). The opposite was predicted for posterior (negative horizontal) misalignments. Proximal (positive vertical) misalignments would cause only distal movements of the calf band while distal (negative vertical) misalignments would cause only proximal movements of the calf band. Anterior-posterior misalignments were found to have a much larger effect on the amount of calf band travel than proximal-distal misalignments.

scholarly journals Ankle-foot Orthosis With an Oil Damper Versus Nonarticulated Ankle-foot Orthosis in the Gait of Patients With Subacute Stroke: A Randomized Controlled Trial

2021 ◽  
Author(s):  
Sumiko Yamamoto ◽  
Naoyuki Motojima ◽  
Yosuke Kobayashi ◽  
Yuji Osada ◽  
Souji Tanaka ◽  
...  
Keyword(s):  
Power Generation ◽  
Randomized Controlled Trial ◽  
Ankle Joint ◽  
Controlled Trial ◽  
Plantar Flexion ◽  
Vertical Angle ◽  
Power Absorption ◽  
Ankle Foot Orthosis ◽  
Randomized Controlled ◽  
Foot Orthosis

Abstract BackgroundGait improvement in patients with stroke using ankle-foot orthosis (AFO) has been compared to the effects of non-AFO use in previous studies, but the effect of different kinds of AFOs has not been clear. When considering the effect of different kinds of AFOs on gait, the dorsiflexion and plantar flexion moment of resistance is considered a key determinant of functional effect. In this study, the effect on gait of using an AFO with an oil damper (AFO-OD), which has plantar flexion resistance but no dorsiflexion resistance, and a nonarticulated AFO, which has both dorsiflexion and plantar flexion resistance, were compared in a randomized controlled trial. MethodsForty-one patients (31 men, 10 women; mean age 58.4 ± 11.3 years) in the subacute phase of stroke were randomly allocated to two groups to undergo 2 weeks of gait training by physiotherapists while wearing an AFO-OD or a nonarticulated AFO. A motion capture system was utilized to measure shod gait without orthosis at baseline and after training with the allocated AFO. Data analysis was performed focused on the spatial and temporal parameters, ground reaction force, shank-to-vertical angle, and ankle joint kinematics and kinetics. Two-way mixed ANOVA was performed to clarify the effect of AFO use and the difference between the two AFOs. ResultsThirty-six patients completed the study (17 in the AFO-OD group and 19 in the nonarticulated AFO group). Spatial and temporal parameters and ankle joint kinematics were improved after 2 weeks in both AFO groups. Interactions were found for the range of shank-to-vertical angles in paretic single stance and ankle peak power absorption. In the AFO-OD group, both parameters improved when the participants walked with the AFO compared to the shod gait, but there was no change in the nonarticulated AFO group. Power generation was not increased in either AFO group. ConclusionsThe results of this study showed that AFO with plantar flexion resistance but without dorsiflexion resistance improved the range of the shank-to-vertical angle and ankle power absorption but not power generation in a paretic stance. (336/350 words)Trial registration: UMIN000028126 Registered 1 August 2017,https://upload.umin.ac.jp/cgi-bin/icdr/ctr_menu_form_reg.cgi?recptno=R000032197

Effect of Shoes on Stiffness and Energy Efficiency of Ankle-Foot Orthosis: Bench Testing Analysis

2017 ◽  
Vol 33 (6) ◽  
pp. 460-463 ◽  
Author(s):  
Toshiki Kobayashi ◽  
Fan Gao ◽  
Nicholas LeCursi ◽  
K. Bo Foreman ◽  
Michael S. Orendurff
Keyword(s):  
Mechanical Properties ◽  
Energy Efficiency ◽  
Lower Limb ◽  
Plantar Flexion ◽  
Foot Orthoses ◽  
Testing Device ◽  
Ankle Foot Orthosis ◽  
Ankle Foot Orthoses ◽  
Bench Testing ◽  
Foot Orthosis

Understanding the mechanical properties of ankle-foot orthoses (AFOs) is important to maximize their benefit for those with movement disorders during gait. Though mechanical properties such as stiffness and/or energy efficiency of AFOs have been extensively studied, it remains unknown how and to what extent shoes influence their properties. The aim of this study was to investigate the effect of shoes on stiffness and energy efficiency of an AFO using a custom mechanical testing device. Stiffness and energy efficiency of the AFO were measured in the plantar flexion and dorsiflexion range, respectively, under AFO-alone and AFO-Shoe combination conditions. The results of this study demonstrated that the stiffness of the AFO-Shoe combination was significantly decreased compared to the AFO-alone condition, but no significant differences were found in energy efficiency. From the results, we recommend that shoes used with AFOs should be carefully selected not only based on their effect on alignment of the lower limb, but also their effects on overall mechanical properties of the AFO-Shoe combination. Further study is needed to clarify the effects of differences in shoe designs on AFO-Shoe combination mechanical properties.

scholarly journals A Portable Ankle-Foot Rehabilitation Orthosis Powered by Electric Motor

2015 ◽  
Vol 9 (1) ◽  
pp. 982-991 ◽  
Author(s):  
Yang Bai ◽  
Xueshan Gao ◽  
Jun Zhao ◽  
Fei Jin ◽  
Fuquan Dai ◽  
...  
Keyword(s):  
Ankle Joint ◽  
Electric Motor ◽  
Plantar Flexion ◽  
Structure Design ◽  
Foot Drop ◽  
Installation Space ◽  
Joint Movement ◽  
Loop Control ◽  
Ankle Foot Orthosis ◽  
Foot Orthosis

Powered ankle-foot orthosis can not only prevent foot-drop and assist patients’ walking but also improve the ankle joint movement for patients with dysfunction caused by the various injuries and nervous system diseases. Common ankle rehabilitation devices limit the ankle injury patients’ rehabilitation training within fixed places, so a portable powered ankle-foot orthosis is presented in this paper to enable the patients to continue their work normally with the treatment. The orthosis employs electric motor drive mode to provide ankle dorsiflexion and plantar flexion assistance during patient’s walking. First, the ankle-foot dynamics model is established and the gait is analyzed for the powered ankle-foot orthosis system. Then, a new mechanical structure including wearing parts, analogous ankle joint and transmission is described. For the small installation space between the instep and the knee, the compact transmission mechanism has been given more attention and the finite element method is adopted to optimize the key structure after the force analysis. In addition, the closed-loop control system is chosen for the orthosis position and speed control. At last, wearing and movement experiments on the prototype are carried out, which validates the stability and rationality of the structure design and the effectiveness of the motion control. It has great significance in promoting patient's rehabilitation to help them return to the society.

Development of Six-DOF Human Ankle Motion Control Device Using Stewart Platform Structure for Fall Prevention

2016 ◽  
Vol 28 (5) ◽  
pp. 654-663 ◽  
Author(s):  
Kenta Nomura ◽  
◽  
Teru Yonezawa ◽  
Hiroshi Takemura ◽  
Hiroshi Mizoguchi
Keyword(s):  
Ankle Joint ◽  
Control Method ◽  
Plantar Flexion ◽  
Gait Training ◽  
Stewart Platform ◽  
Human Gait ◽  
Ankle Foot Orthosis ◽  
Six Dof ◽  
The Subject ◽  
Foot Orthosis

[abstFig src='/00280005/06.jpg' width='300' text='Developed device' ] According to a worldwide WHO survey, about one-third of people at the age of 65 or older experience at least one fall a year, which may result in a severe injury. Meanwhile, the population of the developed world is increasingly aging, and fall incidents can be therefore considered as a global problem. The causes of falls include the weakening of the tibialis anterior and gastrocnemius muscles that respectively play important roles in the dorsal and plantar flexion of the foot, and deterioration of the functions necessary to recover balance from perturbations during gait. Such dysfunctions are treated with rehabilitation provided by physical therapists and with special gait training in which the patient is subjected to perturbations. Although devices for rehabilitation and gait training have been developed, they are problematic since they only allow the ankle joint to move at a low number of degrees of freedom (DOF). In this study, we developed an ankle foot orthosis to provide six-DOF control of the ankle joint using a parallel link mechanism known as a Stewart platform. The Stewart platform construction makes it possible to provide six-DOF control. Since the ankle foot orthosis can be applied to walking, it can assist walking or gait training. In one of our prior studies, we proposed a force control method for the device, and verified its accuracy. In the present study, we improved the attachment method and introduced a pressure sensor to the previous version of the device to allow implementation of a new method that enables control adapted to the human gait. In addition, we conducted four experiments to verify whether it is possible to reproduce the physical therapist’s rehabilitation manipulations without limiting the ankle joint’s DOF, provide arbitrary walking assist action, and impart perturbations to the subject during gait. The first experiment verified the device’s accuracy in reproducing motion, the second confirmed the dispersion of the reproduced motion, the third assessed the walking-assist performance to prevent trips, and the fourth ascertained whether it is possible to make the subject lose balance by the imparted perturbation. The results demonstrated that the motions can be reproduced with high accuracy and with low dispersion and that the ankle joint motions can be controlled adaptively to fit the subject’s gait, suggesting the usefulness of the proposed device.

Defining the Mechanical Properties of a Spring-hinged Ankle Foot Orthosis to Assess its Potential Use in Children With Spastic Cerebral Palsy

2014 ◽  
Vol 30 (6) ◽  
pp. 728-731 ◽  
Author(s):  
Yvette L. Kerkum ◽  
Merel-Anne Brehm ◽  
Annemieke I. Buizer ◽  
Josien C. van den Noort ◽  
Jules G. Becher ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cerebral Palsy ◽  
Knee Flexion ◽  
Spastic Cerebral Palsy ◽  
Gait Performance ◽  
Ankle Foot Orthosis ◽  
The Moment ◽  
Potential Use ◽  
Foot Orthosis ◽  
Walking Energy Cost

A rigid ventral shelf ankle foot orthosis (AFO) may improve gait in children with spastic cerebral palsy (SCP) whose gait is characterized by excessive knee flexion in stance. However, these AFOs can also impede ankle range of motion (ROM) and thereby inhibit push-off power. A more spring-like AFO can enhance push-off and may potentially reduce walking energy cost. The recent development of an adjustable spring-hinged AFO now allows adjustment of AFO stiffness, enabling tuning toward optimal gait performance. This study aims to quantify the mechanical properties of this spring-hinged AFO for each of its springs and settings. Using an AFO stiffness tester, two AFO hinges and their accompanying springs were measured. The springs showed a stiffness range of 0.01−1.82 N·m·deg−1. The moment-threshold increased with increasing stiffness (1.13–12.1 N·m), while ROM decreased (4.91–16.5°). Energy was returned by all springs (11.5–116.3 J). These results suggest that the two stiffest available springs should improve joint kinematics and enhance push-off in children with SCP walking with excessive knee flexion.

scholarly journals Stiffness control in posterior-type plastic ankle-foot orthoses: Effect of ankle trimline Part 2: Orthosis characteristics and orthosis/patient matching

1996 ◽  
Vol 20 (2) ◽  
pp. 132-137 ◽  
Author(s):  
T. Sumiya ◽  
Y. Suzuki ◽  
T. Kasahara
Keyword(s):  
Plantar Flexion ◽  
Measuring Device ◽  
Ankle Foot Orthosis ◽  
Maximum Resistance ◽  
Severe Spasticity ◽  
Ankle Foot Orthoses ◽  
Final Adjustment ◽  
Flexion Strength ◽  
Foot Orthosis ◽  
Selection Of

The hingeless plastic ankle-foot orthosis (AFO) changes stiffness largely depending on how much plastic is trimmed around the ankle. To support proper selection of the orthosis and final adjustment of the orthotic stiffness, the correlation between the posterior upright width and the resistance to dorsi- and plantar flexion movements was measured in 30 posterior-type plastic AFOs. The posterior upright width was varied by regularly trimming around the ankle in nine stages. The resistance to dorsi- and plantar flexion movements was measured by bending the plastic AFOs 15d` with the measuring device described in Part 1. All the plastic AFOs decreased in their resistance to both movements in proportion to the reduction of the posterior upright width. The maximum resistance to plantar flexion movement was about 28 Nm, which was strong enough to assist dorsiflexion in patients with severe spasticity. On the other hand, the maximum resistance to dorsiflexion movement measured was about 10 Nm, which was insufficient to stabilise the ankle in patients who lacked in plantar flexion strength. These findings suggested that this type of plastic AFO should be prescribed for patients who predominantly require dorsiflexion assist, and that the orthotic stiffness could be finally adjusted by trimming to exactly meet individual requirements.

Customized design and additive manufacturing of kids’ ankle foot orthosis

2020 ◽  
Vol 26 (10) ◽  
pp. 1677-1685 ◽  
Author(s):  
Harish Kumar Banga ◽  
Parveen Kalra ◽  
Rajendra M. Belokar ◽  
Rajesh Kumar
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
3D Printing ◽  
Gait Cycle ◽  
Foot Drop ◽  
Human Gait ◽  
Content Type ◽  
Ankle Foot Orthosis ◽  
New Material ◽  
Foot Orthosis

Purpose The purpose of this study is improvement of human gait by customized design of ankle foot orthosis (AFO). An has been the most frequently used orthosis in children with cerebral palsy. AFOs are designed to boost existing features or to avoid depression or traumatize muscle contractures. The advantages of AFO’s utilized for advancement in human walk attributes for the improvement in foot deformities patients or youngsters with spastic loss of motion. In this research on the customized design of AFO's to improve gait, there are limitations during walking of foot drop patients. In children with foot drops, specific AFOs were explicitly altered to improve parity and strength which are beneficial to walking positions. Design/methodology/approach This study proposes the customized design of AFOs using computerized and additive manufacturing for producing advances to alter the design and increase comfort for foot drop patients. Structuring the proposed design fabricated by using additive manufacturing and restricted material, the investigation was finalized at the Design Analysis Software (ANSYS). The system that performs best under investigation can additionally be printed using additive manufacturing. Findings The results show that the customized design of AFOs meets the patient’s requirements and could also be an alternative solution to the existing AFO design. The biomechanical consequences and mechanical properties of additive manufactured AFOs have been comparable to historically synthetic AFOs. While developing the novel AFO designs, the use of 3D printing has many benefits, including stiffness and weight optimization, to improve biomechanical function and comfort. To defeat the issues of foot drop patients, a customized AFO is used to improve the human gait cycle with new material and having better mechanical properties. Originality/value This research work focuses on the biomechanical impacts and mechanical properties of customized 3D-printed AFOs and compares them to traditionally made AFOs. Customized AFO design using 3D printing has numerous potential advantages, including new material with lightweight advancement, to improve biomechanical function and comfort. Normally, new applications mean an incremental collection of learning approximately the behavior of such gadgets and blending the new design, composite speculation and delivered substance production. The test results aim to overcome the new AFO structure issues and display the limited components and stress examination. The outcome of the research is the improved gait cycle of foot drop patients.

PROPULSION SYSTEM WITH PNEUMATIC ARTIFICIAL MUSCLES FOR POWERING ANKLE-FOOT ORTHOSIS

2013 ◽  
Vol 43 (4) ◽  
pp. 3-16 ◽  
Author(s):  
Ivanka Veneva ◽  
Bram Vanderborght ◽  
Dirk Lefeber ◽  
Pierre Cherelle
Keyword(s):  
Ankle Joint ◽  
Position Control ◽  
Human Motion ◽  
Propulsion System ◽  
Joint Torque ◽  
Joint Control ◽  
Artificial Muscles ◽  
Ankle Foot Orthosis ◽  
Pneumatic Artificial Muscles ◽  
Foot Orthosis

Abstract The aim of this paper is to present the design of device for control of new propulsion system with pneumatic artificial muscles. The propulsion system can be used for ankle joint articulation, for assisting and rehabilitation in cases of injured ankle-foot complex, stroke patients or elderly with functional weakness. Proposed device for control is composed by microcontroller, generator for muscles contractions and sensor system. The microcontroller receives the control signals from sensors and modulates ankle joint flex- ion and extension during human motion. The local joint control with a PID (Proportional-Integral Derivative) position feedback directly calculates desired pressure levels and dictates the necessary contractions. The main goal is to achieve an adaptation of the system and provide the necessary joint torque using position control with feedback.

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