I'm keenly waiting the answer to this myself. I have a horse that possibly has this injury - won't know until we do arthroscopy. I'd love to know how any have recovered, as well.
Not a horse but my dog did his cruciate ligament.
For about 3 months he was stuck in a cage then slowly got taken out for short walks etc and slowly built it up. The vet wasn't entirely sure he'd ever be fully fit to work but they said he'd recover enough to be a pet easily though.
After about six months he was fully fit and back into work. The only down side is that he has to have tablets everyday to stop arthritis getting him (he's only young).
A friend's horse had this. He had surgery on it and then box rested for about 6 months I think.
I don't know the ins and outs of it but he is now back in work. He is only up to lightish work but he can happily school on the flat and hack out and is very happy.
OUr dog had his operated on about 3 months ago - probably not the same op they do on horses but he's recovered really well, although it now looks like he might have done the other one