Moving on From Metal

We finally got a small reprieve from all of the metal bending and were able to design plastic wrist hand orthoses today.  Creating a plastic molded device means first creating the mold...I think it is easy to see where this is going...back to the world of plaster molds!!  Casting a patient and then using the cast to create the mold that then becomes the form to vacuum plastic around for the device.

To the left, you can see the bits and pieces that make up my cast of the forearm, fingers, and thumb.  In orthotics, because it is focusing on correcting limbs rather than supplementing for not having a limb, we mainly use each other as patients.  For this assignment, we were each given a classmate partner and a random diagnosis to create a custom WHO around.  I loved that everyone had a different pathology to work from because it meant there were 17 different projects in the class and it gave everyone a chance to research their own diagnosis and have to use what we are learning to decide what type of orthotic device would be necessary for that diagnosis.

My patient sits caddy-corner to me in the workroom and the diagnosis I was given was a "tendon laceration of the flexor digitorum superficialis."  Yes, it sounds fancy and too many words for what the simple, watered-down version actually is...a suicide attempt by slitting the wrist.  How pleasant, right??

So, after researching, I learned that the brace needed for a cut tendon is one that keeps the tendon immobile and gives it time to rest in order to heal.  The flexor digitorum superficialis goes down from the wrist into the fingers and is what would help you wave "bye-bye" if you were a toddler.  It curls the fingers down.  In order to keep this tendon from moving, my job was to make an orthotic brace that held the forearm and the fingers in one position - one where they could not be flexed or extended.  The nice part about creating orthotics is that the casting and modifying goes much quicker than it does in prosthetics.  Because I was creating a brace that was only going to go on the wrist and palmar side of hand and it was a device that was just going to fit on the patient's current forearm/hand, all I had to do in modification was smooth up my cast to get it ready for the plastic.  I was also able to cut my thumb portion off because the thumb is not moved by the tendon that was injured in my diagnosis and therefore does not have to be included in the brace.  My patient is not able to move a single one of his fingers, but he can let his thumb go wild!

Vacuum forming plastic is exactly the same as it was in prosthetics - simply drape the melted plastic sheet over the mold and turn on the vacuum switch to get it to mold to the cast.  It also still makes me equally panicky as it did in prosthetics.  I am getting better at handling the flimsy burning hot, drooping plastic square from the oven, but I still get anxious about the timing of it all and getting it right on the first try.  Luckily, I got this one right on and had the flexibility of knowing I was cutting off the entire back portion of this brace so putting a seam in it or a wrinkle in the back was not going to ruin the project.  Phew :)

And this is what my WHO looked like by the end of the day.  Like I said, it goes much faster in orthotics so I was able to get from the casting point to this point in one day - completely unheard of when I was working on a leg in prosthetics!!  This device is not made for me (as you can tell it is much too big in the picture), but this way you can get an idea as to where I am going with the project.  It keeps the patients fingers in a relaxed position and the forearm supported.  It provides total contact on the affected side and also can easily be removed for hygienic purposes.  Up next is to smooth out the plastic around all of the edges, fit it on my patient and make sure the trim lines are in the right place and then to sew and attach the velcro straps.  As you can tell by my filthy and cluttered workbench, this was a good stopping point for the day - it was a long time in the lab and I need the rest to gear up for attempting to make nice with the sewing machine for my straps.  A completed plastic WHO and a critique to immediately follow are up next on the agenda.  Stay tuned...