ascott said:Is he acting "normal" or is he being quiet?
Tom said:What are you using for UV? Does he ever get sunshine? What species and age? Diet? What do you gut load your insects with?
Tom said:I see three possibilities:
1. Edema. I had a friends Jacksons cham do this when he was primarily using carrots to gut load the insects. His was doing it on all of the legs though. We thought it looked like MBD, but this cham lived outdoors near the beach. He stopped gut loading with carrots, at his vets recommendation, and the problem disappeared.
2. An old injury that healed that way. He might have had a break for some reason and it just healed that way. Your old pics make this a likely scenario. Nothing to do about it now.
3. MBD. If he's not seeing the sun, this is a possibility. Is your bulb new? Is it a coil type? Does he go near it? I would also expect to see the lower jaw swelling and possibly something on the other limbs too, if this were the case.
Here is a good site for chameleon info:
http://www.chameleonforums.com/care/chameleons/
Those people know far more than me, and they are more current too.