I don’t have arthritis but have a similar problem with the C chord. My fretting index finger is fairly disabled due to punching a guy in the forehead when I was 16 years old. Oh the follies of youth! I can’t bend it fully or completely straighten it.

I’ve wanted to be a guitar player for most of my life and have given up in the past because of this. I’ve also tried to be happy playing the bass since I didn’t need to fret chords. Well, this past year is so I decided I’d give it my best effort now at 48 years old. I am doing what I can to work around my finger. If I have to switch to a C chord I will often hold the 5th string C barre which I can do with no problems. Not the same voicing but better than giving up.

No sage words of wisdom, just came in to add a voice of brotherhood.