Vet seems to think the prognosis is good at this stage [though there is STILL no definite diagnosis as she needs notice to book the x-ray machine and related specialist equipment and personnel] and the article I just read indicates that in most cases the prognosis is good to excellent that the horse will return to healthy function and be able to work athletically just as well as any other horse.
Assuming, of course, that the OCD is caught in time. article
which explains what it is better than I did, what the risk factors are, how it usually presents, and what the treatment is. I fail to see why surgery for it should cost over $6000 but that's what has been estimated if box rest doesn't clear it up.
X-rays first, though, before I get ahead of myself. Can't set up a plan of attack for if box rest doesn't work, without x-rays to find out exactly what is wrong in the first place.
In Magic's case it's her off side stifle though OCD usually affects horses on both sides of their bodies, not just one, and she did trot up lame after the flexion test on her nearside hind, which was done before the test on her bad leg.