They already went over it a few times.
The most memorable time wasearly in the showwhen he gave a lecture to a class and used his experience with his leg as a teaching tool.
It came down to being stubborn: he didn't want to lose his leg and wanted to undergo a certain procedure (or whatever) that would keep his whole leg and all mobility at the risk of it being dangerous. His doctors, including a younger Cuddy, wanted to amputate. But he told them what they could do with their opinion.
In the end, Cuddy convinced his girlfriend to make a decision once he was unconscious... it was a compromise between what he wanted and amputation... cutting off a large chunk of thigh muscle (instead of doing nothing and cutting the whole thing off).
More recently, I think someone had a conversation with him asking why he didn't (or doesn't now) just amputate... he'd be in less pain and just about as mobile. I forget his answer but I think he dodged the conversation by saying something like it was his leg and he'd grown attached.