This is a picture sent by a friend. He broke his collar bone in a bike accident. Clearly it was the other collarbone.
The patient asked:
Shouldn't they have been able to tell which one was broken?
That was probably true in this case, but it's a generally accepted patient safety practice to mark the surgical site (in this case they marked the “wrong” side). It's probably better to ALWAYS follow the process, even when it seems silly, instead of picking and choosing when you have to mark the site. When it's an ACL repair, it's less obvious which knee was damaged and a wrong-site error could occur.
More info on “Correct Site Surgery” (a positive view) from the AORN: LINK