Polio Brace: EZ Knee

The objective is to design an orthotic knee brace that can be unlocked with one hand without bending over.  This could be for unlocking during each step while walking or for unlocking the knee to sit.  The knee must lock straight during stance phase.

This project is mainly aimed towards helping polio patients who have limited function or muscle mass in one or both legs.  These patients are not amputees but need a brace to walk because their legs cannot support them.  This brace is specifically targeted to the developing world.

Current Model

Currently, the Jaipurfoot Organization uses a ring lock knee that requires the patient to bend over to pull up ring locks in order to bend the knee from its straight leg position.  This knee joint needs improvement because the patient must always walk with straight leg gait, because releasing the lock requires bending over.  Additionally, sometimes it is difficult to completely lock or unlock the ring locks.  Our project aims to make a knee that is easier to lock from an upright position.  In addition, we hope to address the robustness of the lock by having a spring loaded pin that automatically locks when straight.

SolidWorks Model of Locking Joint

Our prototype improvements included adding a plastic foot, a wider range of motion, a decrease in “sticking” in the spring, and an alignment system to ensure that the two knee joints bend in unison in parallel planes.

This research was supported by designs from Kingsley Orthotic and Prosthetic Supply, by information from Becker Orthopedic and JSB Orthotics & Medical Supply, and by interviews with Sanjeev Kumar of the Jaipurfoot Organization and Bob Emerson of Lifestyle Prosthetics and Orthotics.

EZKnee Prototype

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