How are people in full body casts supposed to masturbate?

I’ve heard that if a man doesn’t at least rub his penis every so often, he will get atrophy and it will shrink on him. It’s only temporary, but it’s obviously not good. So how are people with broken arms and whatnot supposed to masturbate? In the 1800s, even though the nurses were trained in medicine a little, they were actually prostitutes and would give a guy one last fuck before he dies. Does that still go on today?