On bikejournal, someone would pipe up and suggest a recumbent and I always grumble with disappointment at the bent poster. But, have you considered a recumbent?
I have a friend who's gone bent after surgery removed much of the musculature in her shoulder. She could still ride a DF, but only with pain. I, too, have gone bent. I didn't do it because of pain, but I'm never going back to a DF due to lack of pain.