Design of Mechanism and Preliminary Field Validation of Low-Cost Transfemoral Rotator for Use in the Developing World

Abstract

Transfemoral (above-knee) amputees face a unique and challenging set of restrictions to movement and function. Most notably, they are unable to medially rotate their lower-leg and subsequently cross their legs. The best and most common solution to this issue today is a transfemoral rotator, which allows medial rotation of the leg distal to the knee through a lockable turntable mechanism. However, currently available transfemoral rotators can cost thousands of dollars, and few equivalent technologies exist in the developing world. This paper, supported by the results of field studies and user testing, establishes a framework for the design of a low-cost and easily manufacturable transfemoral rotator for use in the developing world. Two prototypes are presented, each with a unique internal locking mechanism and form. A preliminary field study was conducted on six transfemoral amputees in India and qualitative user and prosthetist feedback was collected. Both prototypes successfully allowed all subjects to complete tasks such as crossing legs, putting on pants, and tying shoes while maintaining functionality of walking and standing. Future iterations of the mechanism will be guided by a combination of the most positively received features of the prototypes and general feedback suggestions from the users.

Design of a Passive, Shear-Based Rotary Hydraulic Damper for Single-Axis Prosthetic Knees

“…The primary goal of this study was to create a damper design that can provide accurate control of single axis knees, allow smooth transition between stance and swing phases, and can be integrated in the popular single-axis architecture of prosthetic knees. The overarching theme of the current research is to design all the modules required to assemble an affordable, passive knee prosthesis which can enable able-bodied gait for above-knee amputees in developing countries, based on the prior work done by Narang, Arelekatti and Winter [1][2][3][4][5][6][7][8].…”