I completely severed my thumb muscle and have almost no use of my left thumb. Try doing something without a thumb. I don't know, maybe you already know what I'm talking about.
Let us say I have a very polite and non offending left hand, I also did damage to the thumb, at the skin end of the nail I cut little more than 1/2 way though.(palm side going to nail) Had an extraordinary surgeon that tied the end of the muscle by way of "thread" up through "material", of which I lost some of, and through the thumb nail and tied it to a button. Maybe you can picture that, just do not know how to describe it better. End of thumb has no feeling, used to be a part time cabinet maker,may still be just have not had the time to try and make a really fine piece, will most assurely will be more difficult and slower. I have seen a button tool for people than have arthritus, if I can find it again I will certainly let you know.