A Prosthetic Ankle Design to Improve Stair Ambulation for Transfemoral Amputees

Abstract

The aim of this thesis is to design a prosthetic ankle to improve stair ambulation for transfemoral (above knee) amputees. Even though many prosthetic knees offer stair descent capabilities, no prosthetic ankle provides a natural stair descent gait for transfemoral amputees. Most ankles have a limited range of motion resulting in transfemoral amputees placing their heel on the edge of the step and rolling over the foot. This causes increased loads on the intact limb as well as increased risk of falling. This thesis presents a prosthetic ankle design that provides the user with a more natural stair descent gait by allowing the ankle to move into dorsiflexion (toe points up) during stair descent. As a part of the design process a gait analysis study is conducted. Transfemoral amputee stair descent gait is recorded and the results presented. The final design is presented along with a finite element analysis. The presented design will help reduce the increased loads acting on the intact limb and likely reduce the risk of knee pain developing in transfemoral amputees’ intact leg. It will also reduce the risk of falling by allowing a greater amount of the foot to remain in the step during stair descent.