My chum Joe Adams, dead these past four years, had hands badly crippled from rheumatoid arthritis. He tuned his guitar to an open tuning, with a raised nut à la Hawaiian guitar, and used a steel and flat-pick. He also devised a capo which allowed him to play in different keys without retuning -- it had a bar between the strings and fingerboard as well as over the strings. He was crippled up throughout his adult life, and music was his therapy. A very inspirational guy.