^It's been a while since I watched TDK but yes, I'd also agree that I couldn't quite figure out how or when Bruce was supposed to have been so badly injured as to require the cane.
I liked how in Batman Beyond
, Bruce got his limp after Joker stabbed him in his leg forcing him to retire. Joker being Batman's nemesis was the one to end his career. They should have done something like that for the end of TDK.