Great story Littleman. We had a similar issue with a couple of our dogs. One of our bitches tore both of her ACLs, we had them repaired at great cost as you know. The surgery didn't take and she was basically left with two mostly useless back legs. Parents decided to give her a chance, within a couple of days this dog was running around on her FRONT legs. Back legs weren't being used at all just skimming the ground. She continued like this for about a year, even hunted happily and without incident. Her front end became extremely large and muscular while her back end wasted away. She was in no pain and very happy, even the vets said to just leave well enough alone. Finally she began using her back legs again. Slowly but surely she put more and more weight on them and used them for walking/running. Then she was fine. Musculature went back to normal and she never had a lame step for the rest of her life. She lived a good 3-4 yrs after that until she got a very aggressive form of mammary cancer.
It's fascinating what the body can do if it needs to.