I've done it plenty of times, and will probably do so again in the future. Heck, I've got scars on both knees and both forearms, too (although the forearm ones are less visible than they used to be because my last two crashes opened them up and made them heal better the second time around). Most people I know understand that these things happen, and few of them make any comment about it anymore, beyond making sure I'm alright. The only thing that might worry me is if it's the sort of event that might aggravate that injury -- then I'd be concerned.