טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentDegtyar Andrey
SubjectFlexible and Adaptable Ankle Foot Orthosis for Walking
Style Correction of Post Stroke Patients
DepartmentDepartment of Mechanical Engineering
Supervisors Professor Oleg Gendelman
Dr. Oleg Verbitsky
Full Thesis textFull thesis text - English Version


Abstract

The purpose of this study is to develop and design a Flexible and Adaptable Ankle Foot Orthosis (FAAFO) device based on classic mechanical principles as well as ankle biomechanics. The FAAFO is designed to correct ankle joint rotation trajectory during the gait and walking style. The device is also designed to prevent foot slap, forefoot drag and forefoot collision with the ground due to the dedicated linear spring assemblies with adjustable stiffness. The FAAFO can be applied directly to a foot or a shoe.

The FAAFO design is based on three linear spring assemblies for ankle support and two flexible straps for knee support. The central spring assembly prevents foot drop (pantarfelxion 10°) while the two side spring assemblies prevent the over-rotation of the foot. The main design requirement is to develop a low cost, easy to use, unisize, unisex and a device adaptable for each user.

The in vivo exploration of the device has been performed on four post stroke patients with foot drop syndrome. Video capturing was done with help of mobile video camera (1080P, 30FPS).The tests were conducted with the help of the VICON optical system. For patients 1, 2 and 4 a one-way ANOVA model was used to evaluate the differences between the three treatment factors (gait without any device, gait with the original device and gait with the use of a FAAFO device). For patient 3 a one-way ANOVA model was used to evaluate the differences between the two treatment factors (gait without any device, and gait with the use of a FAAFO device). The P-values were evaluated according to three-valued logic: “it seems to be positive”, “it seems to be negative” and “judgment is suspended”.

The results of the experiments show that FAAFO improved the gait of patient 2 resulting in close to normal ankle joint rotation trajectory in sagittal plane.

For patient 2 and 3 the ANOVA test results are “seems to be positive” in favor of FAAFO. The statement is based on the measurement results of the ankle joint rotation amplitude in the sagittal plane (absolute value of difference between dorsiflexion, stance maximum and plantarflexion, swing minimum).

According to the raw data maximum ankle joint rotation amplitude in the sagittal plane was observed during FAAFO usage for patients 1, 2 and 3.

Current research shows that FAAFO usage leads to the correction of the ankle joint rotation trajectory and ankle joint rotation amplitude in the sagittal plane during the gait. In addition, one can conjecture that the usage of FAAFO also promotes rehabilitation of the lower body muscles, but further exploration is required to clarify this point.