Biologically inspired knee prosthesis

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There is a significant need for better prostheses solutions for individuals with above-knee (AK) amputation. Despite improvements made by introducing micro-controlled knees and energy returning feet, individuals with AK amputation that use contemporary prostheses still have significant gait asymmetry, are at a higher risk of falls, and expend more energy compared to non-amputees. One factor that has not changed much in the past four decades is the “kinematic” design of prostheses the properties of its design that governs how it moves the lower-leg relative to the upper leg. The polycentric knee introduced in the 1970's that employs a planar linkage for providing stance (lock and release) control is still the favored alternative to a fixed hinge. Although more affordable than micro-controlled knees, the inherent stability of polycentric knees can actually be a potential hazard to the amputee should they need to quickly respond to a loss of walking balance. Powered knees will soon be emerging in the commercial market but the current kinematic design solutions will not be suitable for controlling how the knee transfers energy during walking. Engineers must re-think the design philosophy of the prosthetic knee.The long-term objective of this Discovery Grant research is to improve functionality of prostheses for above-knee amputees. The short-term objective is to explore a new approach to the design of AK prostheses that borrows from the salient biological arrangement of tissues of the natural joint that provide an optimal biomechanical system for controlling the prosthesis, while maintaining a parsimonious and economical design approach. The specific aims to be executed are as follows: Aim 1 (Years 1-3) is to design and develop an efficient flexor/extensor mechanism for both active (concentric) and passive (eccentric) control of the knee in the sagittal plane, that utilizes a “bio-mechanical” knee analog to govern kinematic control of the flexion/extension rotation and anterior/posterior translation. Aim 2 (Years 3-5) is to design and develop a power train and actuator control system capable of providing concentric and eccentric control of the biologically inspired knee by regulating power transfer through the prosthesis based on computer algorithms that models how the central nervous system recognizes and automatically regulates movement patterns of the joints. The outcome will be a fully bench-tested prototype of the prosthesis that will be ready for the next phase of development (Years 6-10), which is incorporating ankle-foot control into the prosthesis.