Once the ligament is torn the only thing that can really be done is surgery. There are non-surgical ways to treat an ACL injury before it tears.
My last boy Bubba had a TPLO surgery when he was 3 years old. He had injured both legs as a puppy. Bubba came home with a Robert Jones dressing on his leg to imobilize it for 2 weeks. We had to do leash walked potty breaks only for those weeks, then we slowly began giving him more light exercise.
Once his staples were out I would place him in our bathtub once a day with warm water and massage his leg, hip to toe. I also did stretching exercises with him.
After one year he was running and playing, although slower than before and he couldn't rough house as much, he was a very happy dog. Two years after surgery he was able to jog along side a horse for about a mile without being in pain afterwords. But I also rubbed his leg down with blu emu cream every night after he was so active to help prevent inflammation.
My best advice to anyone who's dog is going to have a ACL surgery is, be sure the orthopedic is very familiar with the procedure. And even though it is hard and just about breaks your heart, it is imperative that the dog does not run around and play until the vet says they can! Bubba was wanting to play after just one week! We entertained him with filling small cardboard boxes with treats and toys and letting him destroy the box to get to them, it would keep his mind active and his body relatively still. There are lots of toys that you can put treats into and the dog has to nose them around to find out how to get them out. These toys are great for a dog who can't be active. Watch your dog's weight while recovering. Excess weight can build fast when they aren't active, and extra weight will cause problems. Spend lots of time cuddling and playing on the floor with your dog during recovery, it makes them feel special and allows them time to have physical contact.