Thursday, December 26, 2013

Up and Running, and Walking

I’m pleased to say that the Center (clinic) is up and running and so are some new patients! Before Christmas we were able to complete three new prostheses and have started work on several others.

The Center invested greatly in a commercial quality convection oven and although we flopped a chocolate cake, the oven is doing a fine job of baking copolymer polypropelene :) For those that don’t know, one way to fabricate prosthetic limbs is called plastic thermoforming. A flat piece of plastic sheet (usually 3 or 5mm thick) is cooked on a teflon sheet at high temperature until chemical bonds are altered and the plastic can flow. The fluid plastic is quickly handled with gloved hands and placed over a modified plaster model of a residual limb. The plastic is sealed to a vacuum system and thus precisely thermoformed into the three-dimensional limb shape and left 24 hrs to cool.

Designing, fabricating, and fitting prostheses is an extremely rewarding craft, and the stories of success do not get much better than what is happening here at Centro de Miembres Artificiales. Meet A-----o:

A-----o is a young man born the same year as my middle brother. This makes him 36 yrs old. TWELVE years ago he lost his right leg above the knee in a traumatic accident, otherwise he is completely healthy. Since then he has used this contraption to restore body image and assist in standing. 

The inside of the prosthetic interface is peppered with metal staples that previously fixed some type of foam or plastic in place :(

He used lots of fabric from an old sweatshirt to pad the interface and help make the oversized and mis-shaped socket wearable. The prosthesis was suspended using a simple belt. The knee is some kind of outside hinge joint and the foot is broken. Everything is held together with some rubber strips. The unit weighs close to 10 lbs.

In comparison A-----o’s new custom made ischial containment socket fits so intimately to his limb that it is suspended solely with suction, aided by a one-way expulsion valve . The copolymer plastic is smooth and strong, yet allows some flex to aid in comfort. Below the copolymer socket is a new polycentric knee made in-house of delrin plastic and designed by Limbs International. The polycentric joint allows mechanical stability in the stance phase of gait and knee flexion in swing to provide normal (-ish) biomechanics and improved ground clearance. Below the knee is a Shape and Roll foot also made in-house of copolymer plastic. The total prosthesis weighs half of what his old one did.

Less than an hour after fitting the prosthesis A----o was walking independently without aids. That is a special thing to watch :) He walked home and left his old “prosthesis” for our museum.

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