If you look closely at a person's knee at full bend, it indeed does look something like what we have here, but the flat-ish part only being 3 or 4 inches rather than the 6 or 7 depicted.
It's an easy photoshop fix, shave down the high part and shift the kneecap. Just a small amount is all that it needs.
It really is funny how easy it is make a human figure look grossly malformed with a very minor change in a ratio.
