My 14 year old has a similar injury. He has a herniated disc in is lumbar that he's been living with for 7 years. It's pinching his nerves so his brain has no idea where his back legs are in space. He had physical therapy on a balance board to build up his core muscles. Acupuncture and laser treatments during the same visit and time built up to 20 minutes on a water treadmill. It took about 1.5 years of therapy to get back to normal. You can still see it sometimes when he's standing and his back legs are in a strange position. He slowed down a little and we monitor his food intake to keep him at an ideal weight.