If I might interrupt this gay-fest a moment, just to say hi spandex, hope you're coping with a little enforced rest, and thanks for the x-rays, I like looking at x-rays what with bones being my specialism, although I'd be more interested if you were a cow or a sheep of course..
I would imagine it's quite possible to snap a bone with no outward sign of damage - well, I know it is, my Mum had no cuts when she did her wrist. The patella is, in humans, as I recall, a flattened lump of bone, so I could imagine it snapping across... I'll have to nip up to the attic later and check one...