Custom 3D Printed Finger Splint

Right before the Christmas break last year, I fell during a local snowboarding competition. Slopestyle under pressure has never been my forte, so as you can see from the video, I fell while making a 180 on a tiny jump. At first, I thought that I just really badly bruised my finger... so it took me a month to finally get an appointment with a doctor that revealed that I had a broken distal phalange of my ring finger. Luckily, all my ligaments and tendons were intact, so the doctor recommended against surgery and reassured me that immobilizing the joint for 6-8 weeks should be enough for it to heal.

Apparently, my fingers are small and short, so after trying on few different finger splints at the doctor's office and at the stores, I've been provided with a sponge-covered piece of metal and tape to fixate it on my finger. At first, I had no problems with this solution, it seemed simple and cheap enough. But over time, I started hating it for the following reasons:

  • I had to change the tape every time I washed my hands
  • Even after changing the tape, it would take a few hours for the splint to fully dry
  • My skin was irritated by tape and constant moisture
  • It was impossible to type wearing that splint
  • The splint was objectively ugly

So, I decided to come up with a better solution to my problem and make my finger's recovery a much more pleasant experience!

Read this instructable if you want to learn how to make an inexpensive finger splint that looks professional, prevents skin irritation, immobilizes your finger and allows you to type comfortably!

Step 1: Step 1: Measure Your Finger

Ideally, for this step, you would need the following:

  1. Calipers
  2. Your fingers (both broken and the same finger from the other hand)!

We will need to make the following 8 measurements as shown on the picture. Measure the finger that is not injured thoroughly and then confirms your measurements on the injured finger.

A: distance from the tip of the finger to the widest point of the first joint

B: distance from the first joint to the widest point of the second joint

C1 and C2 are measured at the A/2 point from the tip of the finger

D1 and D2 are measured from at the widest point of the first joint

E1 and E2 are measured at the B/2 point from the widest point of the first joint.

Write them all down and go over to step 2!

Step 2: Step 2: CAD

For this step you will need:

  1. Any 3D CAD software (I used Autodesk Fusion 360 - it is free for university students)
  2. Your measurements from Step 1

This tutorial assumes that you know how to use CAD, but if not, there are many other resources that can teach you how to use it.

We start by creating 4 planes with the following coordinates:

  1. z=0 (base)
  2. z=B/2 (our joint)
  3. z = (A+B)/2 (middle of the distal phalange)
  4. z = B/2 + A (tip of the finger)

Then, on each plate, create an oval of the following measurements (note x is length, y is width) :

  1. x = E1 y = E2
  2. x = D1 y = D2
  3. x = C1 y = C2
  4. x = C1 y = C2 (this one doesn't matter too much because we will be exposing half of it later

For each of the ovals, create a larger oval around it to make an oval hoop with a wall thickness of .1"

Now, use the Extrusion tool to connect all the oval hoops into one shape. We now have a basic shape of a finger splint!

However, now we need to satisfy our breathability and ability to type with the splint. To do that we have to make some few holes for ventilation and expose the top part of the pad of the finger up until plane #3 (don't go below it, it might destabilize the joint). Also, keep in mind that if you are using an FDM printer, you might need to print with support which will need to be safely removed. The last piece of advice is that the fewer holes there are, the more sturdy the splint will be, but the more holes there are, the more breathable it is.

Be creative!

Save the file as .STL and move on to Step 3!

Step 3: Step 3: 3D Print It!

For this step you will need:

  1. 3D Printer and 3D printing material(any kind is fine, the printing area should be large enough for your CAD model, though)
  2. Patience and time (it might take few tries)
  3. Your fingers (to try it on)
  4. Pliers (to remove support)
  5. Sandpaper (coarse and not so coarse to ensure that nothing scratches your fingers)

We assume here that you have done 3D printing before. If not, refer to a tutorial specific to your printer!

Print your finger splint. If the holes you made in the splint are large, enable the support. I also recommend to enable a raft or at least a skirt to ensure your print got a proper adhesion to a plate.

After your print is done, use pliers and sandpaper to remove the support material from your print. Now, the important part: try the finger splint on your healthy finger first. If the splint fits well enough on your healthy finger and prevents you from moving your distal phalange, then try it on your broken finger. Trying the splint on your healthy finger first minimizes your chances of injuring the broken finger further. The only exception is that if your injury is very recent and your broken finger is still swollen -- then it is pointless to compare it with your healthy finger. Just be very careful when trying it on!

Most likely, your first print is too small/too large. Don't despair, change your model and reprint it! Continue until it fits well. For me, it took 4 iterations to create a splint that fit perfect: it stayed in place without any tape, did not allow the joint to bend, and was not too tight to be uncomfortable.

Well done, you just made your own custom finger splint!

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