Welcome, esben!

I've had some hand problems, mostly due to arthritis, and have often found that rest as well as paying attention to what position my hands are typically in and making a few changes can be helpful.

These routines take time and more time. You just have to wait it out sometimes but eventually you find you've got rid of the pain or stiffness.I wore a splint on one finger for about 10 months on the advice of my doctor because of what is known as a "trigger finger." It was a nuisance, and I had to wear it at night as well as in the daytime, but the finger is now just as good as that finger on the other hand. Neither one of them is capable of as much range of motion as it should be but I already had arthritic changes in my hands. Once your fingers start getting bent out of shape, there's not much that can be done but if you're young enough and lucky, that won't happen to you for a while

Surgery can be an option if the deformity is severe.