If the bones are deformed, they will probably stay that way. However, if even part of the issue is in the joints, you might be able to help him. Try gently massaging each of his toe joints in the affected toes. Start very gently and work toward firmer pressure. Still, you don't need a ton of pressure and the rooster will probably let you know if you do it too hard. You're trying to !slowly! and gently improve range of motion in his toe joints. You can also do a bit of this on his "ankle" joints. Try this on an unaffected chicken to compare the joint feel between the two birds. If he seems to like it or it seems to be helping, keep doing this daily for a week or two and reassess. If he isn't down for even light pressure, the joints may be inflamed. I lean toward the natural end of treatment...I don't know if arnica is safe for chickens but it works well for pain and inflammation for humans. Possibly also try feeding a small amount of cod liver oil, if you have some around the house.