2 1/2 year old w/lameness. HARD CASE!! HELP!

I have a 2 1/2 year old Tennessee Walker that has been having lameness in his left hind stifle area for five weeks now. X-rays and ultrasound showed no tears or "severe" damage, but there was fluid and swelling in the area. We had him on stall rest for three weeks which was extremely hard on him due to being so young. He was very "anxious" and high-strung when I even tried to groom him during this time. After the three weeks of stall rest he seemed to be getting better so we moved him to a small paddock for 1 1/2 weeks. During this time he was still very "full of himself" due to the lack of exercise. He also kept getting himself cast - four times in three straight days (which does not help the stifle injury). We recently felt he was healed so we put him out to pasture and after three days he is very bad and is short-stepping quite badly with the left hind leg. While we know stall rest would get him better faster, again, we also are dealing with a young horse that is quite large. He is probably close to 17+ hands now. Could this be due to growing so fast or is this most likely a soft tissue injury that just doesn't want to heal? What would you recommend to get him better? This is a hard call - we know stall rest would be the best but if he keeps getting cast it could cause greater injury or he could even end up breaking a leg. Any input is greatly appreciated.

Keep him on stall rest but let him out on supervised outings as often as possible to fit his needs. By supervised, I mean take him for a little walk and let him hand graze. If you do let him out, put him by himself if it's possible, and only for a short amount of time. The only other option for extended stall rest is some kind of sedative or calming agent, but I wouldn't go to that before trying the walks in hand.

As far as the actual condition, I have no idea. Your vet can't tell you anyything?

I was going through something similar with my 3 1/2 year old. I was told he was probably going through a growth spurt again. I don't know how soon you're supposed to see a difference in growth after a spurt (lol I know that sounds like a blonde comment which I am), but my gelding was ok after about a week and half of stalled with mild turnout and exercise. I'm really not one to give you advice for this, but am curious to see what others say as I am possibly going through something similar.

Your vet doesn't know whats wrong? Or did I just misunderstand?

More stall rest, NO GRAIN or feed, bermuda, grass, or timothy hay only, and some serious joint supplements. I've seen great results with liquid Acti-Flex 4000. Use some hay pellets or plain beet pulp (no molasses) to mix in supplements.

If he looses weight, feed more hay pellets or beet pulp and add in some fat to his diet. Stay AWAY from grain products or feed during his recovery, to reduce his excitable behavior in the stall and paddock.

These kind of injuries can take a LONG time to heal.

Talk to your vet about joint injections to speed healing.

This guy definitely shouldn't be ridden until well after 3 yrs old. Tall geldings take longer for the bones to close & mature, up to 3yrs old for knees and 5yrs old for hocks. If he was being ridden at all, that could have contributed to his stiffle issue.

I'm thinking that growth spurts can well be part of this problem. Still how to deal with this?
My only thoughts, as well as the diet advice previous, is to continue stall rest, had walk daily (only around a bit, try to keep the speed slower, but try to get a "feel" for what slower speeds are most comfortable with him) Keep a close eye on the swelling, as to not let it increase, feel the area for obvious changes day to day (heat in the area, painful to touch, swelling getting more pronounced, etc) and see how you go for another few weeks..
Does he like stall toys? The wall mounted lick ball-toy seems to have some calming effect on stalled horses, but I cannot say if he will use it, or how effective it may be..I only know that I attempt to get creative with Blue (my TWH), as he is only now 5, and can get a little bored if he is stalled too much. I hand walk, I leave a small radio going, he has a jolly ball and a few stall toys (large stall), and I try to spend extra time with him when the weather gets bad, and turnout is not an option. I play this game with him, simply how to keep his mind occupied, when his legs can't be..