Oh man, that's a tough break, but hey, kudos to you for not wanting to put the guitar down! First thing’s first—you might want to gaze into a lighter guitar neck or even switch to a guitar with a smaller neck profile. Those Strat necks can be chunky and switching it up might reduce the strain on your thumbs.
You could also explore using thumb picks instead of relying purely on finger strength. And don't forget about setting up your guitar action. A lower action means less pressure needed on the strings, which could be easier on your joints.
As for techniques, maybe adapt your style a bit? You know, more strumming and less intricate solos—unless you’re aiming to become the first guitarist to play killer solos with their toes!
Lastly, it's probably worth checking in with a physical therapist who has experience with musicians. They can give exercises specifically tailored to alleviate pain and improve function.
Remember, arthritis might slow down your fingers but let it never slow down the blues—or whichever genre makes your heart sing! Keep strummin’, and keep smilin’!