That's practically every poster on this site, you stupid moron.
Again, as always in these threads, put up or shut up. All these vague and nebulous allusions to possible knee damage out there somewhere that could happen is useless. Punches can cause horrendous and career ending damage. Any strike at all can potentially do this. What people need to prove is that this strike is more likely than others to accomplish this. So far no one on this entire site has ever shown has happened in the history of ever and eventually resorts to one of two responses. Either:
A) Youre stupid and dont know nothing bout fightin' stuff like I do and/or this guy I totally know
or
B) Rampage says his knees hurt.
Again, put up or shut up. If it's either of the above responses, it's useless.