Design and development of a novel viscoelastic ankle-foot prosthesis based on the human ankle biomechanics

Background and aim: In the present study, a new approach was applied to design and develop a viscoelastic ankle-foot prosthesis. The aim was to replicate the intact ankle moment-angle loop in the normal walking speed. Technique: The moment-angle loop of intact ankle was divided into four parts, and the appropriate models including two viscoelastic units of spring-damper mechanism were considered to replicate the passive ankle dynamics. The developed prototype was then tested on a healthy subject with the amputee gait simulator. The result showed that prosthetic ankle moment-angle loop was similar to that of intact ankle with the distinct four periods. Discussion: The findings suggest that the prototype successfully provided the human ankle passive dynamics. Therefore, the viscoelastic units could imitate the four periods of a normal gait.