There are some things you can do to hopefull;y avoid surgery. I would recommend a suppliment that would help to strengthen his muscles and ligaments. And yes every time he gets excited he is going to hurt it again. Try to not let him jimp down from the bed or the couch if he does get up on those. Use warm compresses for 20 minute intervals and that will help. See if your vet will give you a prescription for Deramaxx which I felel workls better than Rimadyl and other [rescription medications. As far as the suppliments you can find them at all pet stores.and follow the instructions on the bottle, most are two times a day. Then if these tips do not seem to stop the limping and holding his leg up as much as you do noy want to have surgery it may be the way you have to go, Please let me know if you havr any other questions.