Introduction: 3D Printed - Thumb + Wrist Immobilization Brace
When a repetitive motion injury strikes - it's a trip to a doctor and potentially a physical therapist. In my case - I was diagnosed with De Quervain's tenosynovitis and a recommendation to immobilize the injured area. This meant that I had to take it easy on my thumb and wrist in order to reduce the inflammation and let the area heal. I was given a series of custom braces first molded out of water-activated fiberglass and then out of thermoplastics. They weren't as aesthetically pleasing as I had hoped - so I made my own. Recovery time is long and if I was going to wear a brace for 6 months I might as well like it. I used whatever materials that I had on hand. However, the customization potential for this product is awesome as there are multiple color options on the market for PLA filament, webbing, velcro and the finger-less glove!
For this project, I used AutoCAD to draw, Fusion360 to model, and a MakerBot to print the form.
Software: AutoCAD, Fusion360 (or your choice of modeling software) and MakerBot Print
Hardware: 3D Printer, Sewing Machine, Heat Gun (or hair dryer)
Supplies: PLA Filament, 3+ feet of 1" Nylon Webbing, 6 inches of 1" Velcro, Lighter, Glove
Step 1: Drawing the Brace
Here you can see the 2D drawing that I made in AutoCAD. I used a tessellation pattern throughout the entirety of the brace. This multi-directional pattern is not only pretty but gives added structural integrity to the brace and allows for great moldability. In previous versions I had left larger areas without any pattern. By default when 3D printed, the PLA would be laid down in one direction and thus these areas were more prone to breaking. In addition to strength, the pattern creates breathe-ability which helps with user comfort.
I saved the drawing as a .dxf file and then imported it into Fusion360. You may draw and model the whole project in Fusion360 or the modeling program of your choice.
The drawing image shown is slightly different than the example model. (The thumb support in the drawing image was made thinner for a subsequent iteration in order to allow for more mobility as my hand/wrist healed)
I have attached the drawing (that corresponds to the example model) for your reference. Please note that my hand is very small. If you are making one for yourself, I recommend printing this file out on paper to figure out scaling and fit for your own hand.
Special thanks to Andreas Bastian for providing me with the tessellation pattern for this project!
Step 2: Modeling
In my model, I extruded the shape to be 3mm thick and then filleted the edge that would be touching my skin. The rounded edge adds comfort by keeping the brace from cutting into your skin. I exported the drawing as an .stl and then used the MakerBot Software to slice the model and prepare a file for printing.
After a series of tests, I found that printing the file without a raft was the best method as it creates a very clean print and you will eventually be molding the brace (so extreme flatness is not as important).
Step 3: Molding
If your injury is severe, here's a good time to get an extra set of hands to help you. I used a heat gun/ hair dryer and molded the brace in sections. You may even use a clamp or some pliers to help you with this as well. I started with the thumb area, then worked on the curve along the vertical length, and finished by tweaking smaller areas bit by bit till I got the right fit.
PLA becomes pliable around 134 degrees Fahrenheit - and the heat gun is super hot! So be careful to not over-melt your brace when you are in this part of the process. Heat small areas in circular motions.
Wear your knit glove as you mold and fit the brace - it will protect your hand from the hot PLA and will give you a more accurate fit.
In addition, you might also think about using hot water to mold the brace. See this wrist brace by piuLAB on Thingiverse as a reference: https://www.thingiverse.com/thing:403001
Step 4: Attaching Straps
I cut (6) sections of 1" wide webbing that were around 6"+ long. I sealed the edges by searing them with a lighter to keep them from unraveling. Then I cut 3 sets of 1-2" lengths of velcro and sewed them onto the ends of the webbing. I inserted the webbing into the slots on the brace, adjusted the lengths and pinned them to fit. I sewed them in place, trimmed the edges and re-sealed any freshly cut webbing.
Step 5: You Are Done!
Here's the finished product. After I made this brace I consulted my physical therapist on the fit and made some minor adjustments per her suggestion. You may want to do the same! Things to take into consideration:
1) Neutral position for your wrist is with your hand tilted slightly up
2) Make sure that your brace does not rub against the already irritated portions of your hand/wrist that you are trying to heal. Your goal is to immobilize and not aggravate your injury!