There is a horse at our stable that did that...came there with the injury. He was on stall rest, small paddock turnout for a year. Vet didn't think he'd heal well enough to go to work.. seems he has. Owner is starting him out in light work. So far, so good.
We just went through months of shock wave and then PRP (Platelet Rich Plasma) for a small lesion on the cranial horn of the medial mensicus. The horse was rechecked and he's sound and moving great. It was only a grade 1 lameness to begin with, though. So that might be a completely different scenario than yours. Also, the horse was on 24/7 turnout throughout the treatments.