I noticed this a year or two ago, that my fingers primarily on the hand I use the mouse with, naturally rest in the position as if they were still holding a mouse or bent to type, my knuckles are also larger then before, they have been like this since.
here are some photographs of the hand I use for the mouse which is the worst. sorry for the poor lighting btw i have eczema/dermatitis on my hands so that's why they are reddish.
My fingers do function somewhat normally I can bend them fully closed and open, but my ringer finger requires more effort to straighten out fully.
so yeah I'm basically wondering what it is, and why it has happened.