As I have intermittent knee problems, I always travel with a folding cane in my carry-on luggage unless I happen to need the cane at the airport. Never been an issue.

While standing in a long ticket buyers' line at a Paris museum, leaning on my cane, a security guard came over and ushered my wife and I to the front of the line. It's a courtesy I didn't know about but apparently common in Paris.