Poor little lad, but I know animals can overcome all sorts of problems, my friends staffordshire bull terrier somehow damaged his spine she has never worked out how he did it. He was operated on and she was told he was unlikely to walk again. With a lot of care from Nantwich vets and love and hard work from her he now walks, runs like a rabbit with it's knickers too tight (honestly that the only was to describe his run!!) and jumps up on this back legs to greet you. As he has little feeling in his bad back leg he knawed the foot away a little so had to wear a boot and a buster collar to stop him doing it again but as his boot is black like him you can't tell from a distance.
I have every faith that Poisdon will have as good a recovery and soon be getting into all sorts of mayhem, big snuggly hugs to him xx