Modular Design of a Passive, Low-Cost Prosthetic Knee Mechanism to Enable Able-Bodied Kinematics for Users With Transfemoral Amputation

There is a significant need for low-cost, high-performance prosthetic knee technology for transfemoral amputees in India. Replicating able-bodied gait in amputees is biomechanically necessary to reduce the metabolic cost, and it is equally important to mitigate the socio-economic discrimination faced by amputees in developing countries due to their conspicuous gait deviations. This paper improves upon a previous study of a fully passive knee mechanism, addressing the issues identified in its user testing in India. This paper presents the design, analysis and bench-level testing of the three major functional modules of the new prosthetic knee architecture: (i) a four-bar latch mechanism for achieving stability during stance phase of walking, (ii) an early stance flexion module designed by implementing a fully adjustable mechanism, and (iii) a hydraulic rotary damping system for achieving smooth and reliable swing-phase control. INTRODUCTION Background and Motivation This paper is a continuation of the work to design a fully passive prosthetic knee to enable able-bodied gait for transfemoral amputees in developing countries, based on a prior design and analysis by Narang, Arelekatti and Winter [1–5]. It is estimated that there are 200,000 above-knee amputees living in India and that 47% of amputees experience change or loss of employment following the amputation [6–8]. Severe social stigma and the economic consequences from having conspicuous disabilities have been well-documented and articulated [5, 9–13], highlighting the need for a low-cost prosthesis that can enable able-bodied gait to mitigate discrimination and increase metabolic efficiency. Relevant Terminology A brief summary of the relevant terms from gait biomechanics used in this paper are laid out briefly for the uninitiated reader (Fig. 1). Proceedings of the ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference IDETC/CIE 2017 August 6-9, 2017, Cleveland, Ohio, USA