I am sure that was a special made heel pin with a rounded tip...
I assure you guys that think this is painful, done right it is surprisingly pleasurable with the right person and "tools". There are custom surgical steel sounding kits made just for this. I haven't done it in many years, but it used to be a little side fetish of mine. The actual worst part about it is the day after it stings a little when you pee. lol
I know that this is the forum for "what ever floats your boat" but I personally have two words for this !! NO and NEVER!!! But again, if it floats your boat ........