Good eye! He had a pretty severe extensor tendon laceration to the left hind in April of 2010. See the puffiness today? That's because he either bumped the leg or twisted it somehow on a trail ride last weekend. We were crossing a shallow creek and he slipped on some slimy rocks...none too gracefully either. I'm going to have the leg x-rayed soon. Thinking he may have a bone sequestrum or something going on there..the wound never fully healed/contracted properly or completely. Pics today were taken on a bit of an incline, I think. Ground is not completely flat there.
Ouch... my mare also had a bone sequestrum last year. She lacerated and punctured her upper fetlock to the bone, chipping the cannon bone. She had to have surgery to have the sequestrum removed. Lots of bandaging
I'd be curious to know how your boy turns out and what's going on there.