• Journal of Biomedical Engineering Research
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• v.22 no.4
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• pp.359-368
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• 2001

A new knee-ankle-foot-orthosis(KAFO) which uses an automatically-controlled electromechanical wrap spring clutch for the knee joint was developed in the present study. It was found that the output voltage from the foot switches of the developed KAFO was proportionally increased with respect to the applied load. The output voltage from the infrared sensor also decreased as the knee flexion angle increased. The knee joint system for the new KAFO weighs only 780g lighter than any other commercially available developed system. In addition, the solenoid reduces the reaction time for the automatic control of the knee joint. The static torque of the clutch was measured for three persons, and it satisfied the normal knee extension moment during the pre-swing. Three-dimensional gait analyses for three different gait patterns (normal gait, locked-knee gait, controlled-knee gait) from five normal subjects were conducted. Controlled-knee gait showed the maximum knee flexion angle of 40.56$\pm9.55^{\circ}$ and the maximum knee flexion moment of 0.20$\pm$0.07Nm/kg at similar periods in the normal gait. Our KAFO system satisfies both stability during stance phase and free knee flexion during the swing phase at the proper period during the gait cycle. Therefore, our KAFO system would be very useful in various low extremity orthotic applications.

• Physical Therapy Rehabilitation Science
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• v.2 no.2
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• pp.81-86
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• 2013

Objective: The objective of this study was to investigate the feasibility and effects of balance training using a newly developed elastic band orthosis (aider) for improvement of mobility and balance in chronic stroke patients. Design: Cross-sectional study. Methods: Ten patients with chronic hemiplegia participated in this study. There were six males and four females; two patients had right hemiplegia and eight had left hemiplegia. This study investigated the effect of the elastic band orthosis on balance and gait ability compared with bare foot condition. Gait parameters were measured using the opto-gait system for analysis of the spatial and temporal parameters of walking in stroke patients. In addition, balance ability in stroke patients was evaluated using the Timed Up and Go (TUG) and Berg Balance Scale (BBS). Results: This study investigated the effect of the elastic band orthosis on balance compared with bare foot condition. The TUG and BBS showed significant improvement with use of the elastic band orthosis (p<0.05). Use of the Elastic band orthosis resulted in significantly improved velocity, cadence, less-affected step length, less-affected stride length, and less-affected single limb support in stroke patients (p<0.05). Conclusions: We demonstrated a significant improvement in dynamic balance and gait ability in chronic stroke patients using the elastic band orthosis. This orthosis may aid in prevention of spastic foot drop, leading to improvement of walking ability.

• Journal of the Ergonomics Society of Korea
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• v.26 no.2
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• pp.131-136
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• 2007

In this study, we developed an active ankle-foot orthosis(AAFO) which can control dorsi/ plantar flexion of the ankle joint to prevent foot drop and toe drag during walking. 3D gait analyses were performed on five healthy subjects under three different gait conditions: the normal gait without AFO, the SAFO gait with the conventional plastic AFO, and the AAFO gait with the developed AFO. As a result, the developed AAFO preeminently induced the normal gait compared to the SAFO. Additionally, AAFO prevented foot drop by proper plantarflexion during loading response and provided enough plantarflexion moment as a driving force to walk forward by sufficient push-off during pre-swing. AAFO also could prevent toe drag by proper dorsiflexion during swing phase. These results indicate that the developed AAFO may have more clinical benefits to treat foot drop and toe drag, compared to conventional AFOs, and also may be useful in patients with other orthotic devices.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.10
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• pp.1526-1533
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• 2004

The needs of walking assistant device such as the Ankle Foot Orthosis (A.F.O) are getting greater than before. However, most of the A.F.O are generally imported rather than domestic manufacturing. The major reason of high import reliability is the rack of impact properties of domestic commercial products. Therefore, this research is going to focus on the evaluation of impact properties of the A.F.O which has the high import reliability. Unfortunately, these kinds of researches are not performed sufficiently. This research is going to evaluate impact energy behavior in composite materials such as the glass/epoxy (S-glass, [0/90]sub 2S/) and the aramid/epoxy (Kevlar-29, woven type, 8 ply) of ankle foot orthosis. The approach methods were as follows. 1) The history of impact load and impact energy due to the various velocities. 2) Relationship between the deflection and damage shape according to the impact velocities. 3) The behavior of absorbed energy and residual strength rate due to the various impact velocities.

• The Journal of Korean Physical Therapy
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• v.27 no.1
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• pp.43-49
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• 2015

Purpose: The aim of the current study was to examine the effects of hinged ankle-foot orthosis (HAFO) on walking function in children with spastic diplegic cerebral palsy (CP). Methods: Thirty-two children (mean age: $6.79{\pm}0.35years$, age range: 5-7 years) who were diagnosed with spastic diplegic cerebral palsy participated in the study. Each subject typically walked through 10 meters of a gait platform with markers on the subject's proper body segments and underwent 3-D motion analysis system with and without hinged ankle-foot orthosis. The HAFOs were all custom-made for individual CP children and had plantarflexion stop at $0^{\circ}C$ with no dorsiflexion stop. The interventions were conducted over three trials in each group, and measurements were performed on each subject by one examiner in three trials. 3-D motion analysis system was used to measure gait parameters such as walking velocity, cadence, step-length, step-width, stride-length, and double support period in two conditions. Results: The walking velocity, cadence, step-length, and stride-length were significantly greater for the HAFO condition as compared to the no HAFO condition (p<0.05). However, no significant difference in step-width and double support period was observed between two conditions. Conclusion: These findings suggest that using the HAFO during walking would suggest positive evidence for improving the spatiotemporal parameters of gait in children with spastic diplegic cerebral palsy.

• The Journal of Korean Physical Therapy
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• v.17 no.1
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• pp.96-107
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• 2005

Objective: The purpose of this study were to investigate the standing balance, dynamic activity in hemiplegic patients according to the types of ankle-foot orthosis(AFO) and to determine the most effective type of AFO for gait training. Method: A prospective study was performed for 16 patients with hemiplegia who was able to walk independently. Static balance and dynamic activity were compared in two condition : 1) barefoot and SPAFO, 2) barefoot and HPAFO. Static balance and dynamic activity characteristics were evaluated by Active Balance while they were standing with in two condition AFO and barefoot. Results: There were significant difference in standing balance between barefoot and wearing SPAFO and HPAFO(p<0.05). There were significant difference in dynamic activity balance between barefoot and wearing SPAFO and HPAFO(p<0.05). There were significant difference in gait speed between barefoot and wearing SPAFO and HPAFO(p<0.05). Conclusion: This study showed that wearing SPAFO and HPAFO gave fair amount of improvement to balance and gait ability of hemiplegic patients.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.1
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• pp.7-14
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• 2002

In this study, a stress analysis is made fur an ankle foot orthosis (AFO) in the view point of structural stability. The investigated AFO is a solid and standard type. To analyze the stress distribution on the neck of AFO, the maximum AFO angular translation data is obtained by gait analysis. The material test of polypropylene is made to obtain the mechanical properties of AFO. The maximum dorsiflexion appears at the midstance in the gait analysis. The experimental angular translation at the top of AFO is about 10.3$^{\circ}$ at mid stance. Three models of AFO with different width of neck are made and analyzed with ABAQUS 6.1. The stress levels and distributions of 3 different width(W$_1$, W$_2$=0.85W$_1$, W$_3$=0.60W$_1$) AFO are investigated. As a result, the standard type(W$_1$) appears to the maximum stresses at the medial edge of cutout area surrounding ankle joint. The maximum stresses of the narrower type(W$_2$) are occured on medial edge and center of ankle. The narrowest type(W$_3$) appears to the maximum stresses at center of ankle. The maximum stresses become smaller as ankle width of AFO is narrower.

• Physical Therapy Korea
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• v.20 no.1
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• pp.64-73
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• 2013

The purposes of this study were to develop a new orthosis controlling ankle and knee joint motion during the gait cycle and to identify the effects of the newly designed orthosis on gait kinematics and tempospatial parameters, including coordination of the extremities in stroke patients. Fifteen individuals who had sustained a stroke, onset was 16 months, participated in this study. Before application of the measurement equipment the subjects were accustomed to walking on the ankle-foot orthosis (AFO) or stance control knee with knee flexion assisted-oil damper ankle-foot orthosis (SCKAFO) for 5 minutes. Fifteen patients were investigated for 45 days with a 3-day interval between sessions. Measurements were walking in fifteen stroke with hemiparesis on the 3D motion analysis system. Comparison of AFO and SCKAFO are gait pattern. The difference between the AFO and SCKAFO conditions was significant in the gait velocity, step length of the right affected side, stance time of both legs, step-length asymmetry ratio, single-support-time asymmetry ratio, ${\phi}$-thigh angle and ${\phi}$-shank angle in the mid swing (p<.001). Using a SCKAFO in stroke patients has shown similar to normal walking speeds can be attained for walking efficiency and is therefore desirable. In this study, the support time of the affected leg with the SCKAFO was longer than with the AFO and the asymmetry ratio of single support time decreased by more than with the AFO. This indicates that the SCKAFO was effective for improving gait symmetry, single-support-time symmetry. This may be due to the decrease of gait asymmetry. Thus, the newly designed SCKAFO may be useful for promoting gait performance by improving the coordination of the extremity and decreasing gait asymmetry in chronic stroke patients.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.3
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• pp.165-175
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• 2008

An ankle-foot orthosis(AFO) is a brace for persons with gait disabilities to support or replace the function of ankle joint. Ankle-foot orthoses(AFO's) are usually prescribed to alleviate the drop-foot by constraining the excessive plantar flexion. The shape and the strength of the AFO are often based on 'trial and error' due to a lack of knowledge of the stress distribution in the AFO. In this study, an improved stress-freezing method was proposed to measure the stress distribution characteristics in the AFO. As a result, a photoelastic material with low freezing temperature was developed to measure the stresses under a person's direct contact loading condition. The three-dimensional stress-1rozen photoelastic models of AFO's for five stages of stance phase such as heel contact, foot flat, mid stance, heel off, and toe off were produced. The results of photoelastic analysis revealed that the stresses developed in the AFO were varied considerably from tensile to compressive or vice versa, during walking. At the posterior part of ankle joint in the AFO, the maximum compressive stress of 1.81MPa was observed in the mid stance, and the maximum tensile stress of 0.74MPa was observed during heel contact. The overall stress levels in the AFO's were low in the toe off phase. The results suggested that the posterior part of ankle joint might be the most fragile part in the AFO.

• Journal of International Academy of Physical Therapy Research
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• v.11 no.1
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• pp.1992-1998
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• 2020

Background: The foot drop stimulator is designed to improve the walking ability of foot drop in patients after stroke, however, studies on clinical effects are still lacking. Objective: To investigate the effect of a foot drop stimulator on the walking and balancing abilities of foot drop patients after a stroke. Design: One-Group (Pretest-Posttest) Design. Methods: All subjects walked in all three conditions: foot drop stimulator (FDS) ankle foot orthosis (AFO) and barefoot. Primary outcome measures were assessed for walking and balance using a 10-m walking test (10MWT) and a timed up and go test (TUG). Secondary outcome measures consisted of a brief user interview, and the patients recorded the advantages and disadvantages of each condition. Results: FDS, AFO, and barefoot conditions showed a statistically significant difference in 10MWT and TUG (P<.001) as a result of comparing three conditions. FDS and AFO were significantly different from the barefoot condition as post-hoc results; however, there was no significant difference between the two conditions (P>.05). Conclusion: In this study, the foot drop stimulator contributed to improving the balance ability, and the walking ability was similar to the effect of the ankle-foot orthosis.