Saturday, July 23, 2011

Flexible splints - v16 and v17

Two failed experiments

The first experiment used a flexible piece of tubing as the proximal strip used to hold the splint against the knuckle. It was very uncomfortable compared to thermalplastic. The edges were the main problem.

V16 - Soft tubing used near the PIP Joint  (knuckle) wasn't comfortable

V16 Bottom view. You can see where the flexible 'joint' is.

It didn't matter because it didn't stay on very long. The fingernail glue came off quickly. I think it partly had to do with eating popcorn at the movies! I didn't think about it at the time; however, eating popcorn, corn-on-the-cob, even french fries maybe have too much grease that could dissolve the nail glue.

Second attempt

I switched back to the thermalplastic PIP joint band and focused on the flexibility of the wishbone.

V17 - Nothing too special. Single flexible section in wishbone. Nail glue failed too quickly.

It didn't hold. I realized the problem is caused by the flexibility of the wishbone. It was causing the head to torque and come loose from the nail.

Solution was to add a piece of flexible tubing between the nail and the splint.

v17 - small section of tubing against nail to allow some movement.

The nail glue was applied to tubing and it held very well. Next, the thermalplastic was heated as normal and direct heat was applied to the tubing on the nail by touching it to the metal shield of the heat gun. With both hot, they stuck without any issue. Then a thin piece of plastic was pulled over the end to hook on the fingernail.

V17 with two flex points. The middle of the wishbone and the fingernal.
I've been wearing this version for 24 hrs and it's holding great. Very comfortable.

I'm wondering if a thinner piece of tubing could be used in non-flexing splints just to get a better hold. If the plastic is too rigid, then all the torque could be causing the nail glue to fail. Distributing some of this energy into the tubing could make the nail end hold butter.

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