A Splint for "Trigger Thumb" (Shallow Thoughts)

Akkana's Musings on Open Source Computing and Technology, Science, and Nature.

Fri, 21 Dec 2018

A Splint for "Trigger Thumb"

It's been a while since my last blog post. Partly that's because I've been busy with other things, like a welding class, learning a lot of great new techniques. But it's also because I've been trying to keep typing to a minimum (not easy for me) because of a thumb problem.

It's called "trigger thumb" and apparently is caused by a tendon that gets stuck in its sheath. It can be caused by repetitive motion, but in my case I just woke up with it one day, after a day when I hadn't been doing anything particularly hand-intensive.

Cortisone injections and surgery are the usual treatment. I may yet try cortisone, but the number of such injections you can get are severely limited (like, twice in a lifetime), and the surgery didn't sound appealing, so I wanted to try other approaches first.

Some discussions I found mentioned splinting. I tried splinting it with a popsicle stick and tape, but a straight splint made it much worse: keeping it straight made it want to stay straight, and after removing the splint it was quite painful to try to bend it. For weeks it just kept getting worse.

But I finally found something that helped: a bent splint. I glued two pieces of popsicle stick together at an angle, and at bedtime I taped them to my thumb so it stayed a little bent overnight. That helped quite a bit. But it was a pain to set up and tended to come loose. I wanted something I could just slip on and off, without going through all that tape, that wouldn't come loose. Preferably with an adjustable angle.

[trigger thumb splint v.1: steel] So I cut some strips of steel, got out the welder and made myself a bent splint. It's tough to weld thin pieces with the MIG welder, and I melted it in places. But it worked amazingly well. I lined it with some Moleskin, and after a few days with it, the thumb definitely started to feel better. The tendon was still popping, but it hurt a lot less and I could start using my hand again. And the metal splint let me adjust how much my thumb was bent, which wasn't true at all with the popsicle stick approach.

Plus, it had a neat sort of Spanish Inquisition/Hannibal Lecter look. It looks like a torture device, but really, it's amazingly comfortable.

The only problem: it was heavy. I could feel it dragging down on my thumb all the time. I wished it was a little lighter.

[trigger thumb splint v.2: brass] The hardware store sells strips of brass that looked like just the ticket. But you can't MIG weld brass, only steel. Good thing I was taking that welding class! I asked the instructor, and he brought in some carbon-bronze filler rod and showed me how to "TIG braze". It's difficult and fiddly: brass melts very easily, and the trick is to get the base metal hot, then bring in the filler rod and blip the TIG pedal just enough to melt the rod so it flows in without melting the base metal. While my instructor made it look easy, when I tried it myself I always ended up getting the temperature too hot and melting some of the brass.

So my splint looks a bit ragged in spots. Still, the finished product works wonderfully, and it's quite a bit lighter than its steel cousin. Dave thinks it still looks Hannibal Lecterish, but that doesn't bother me. I skipped the Moleskin this time: it's comfy enough without it, and it's a lot easier to slip the splint on and off.

I'm still trying to spend less time typing until my thumb heals completely. But with the splint, and occasional ice packs, it's improving, doesn't hurt any more, and I'm hoping I can get by without cortisone.

And besides, isn't it more fun to weld up your own medical equipment? (Don't tell the AMA!)

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