Where are you located? If highly recommend a rehab facility who will monitor his progress and manage his recovery. I only day this because you already invested in the surgery, so you want to make sure he's setup for success for the next 15 years :-)
My Great Dane blew out both knees at a year old...I wish I had learned of rehab programs for him instead of doing it on my own, per the vets "passive range if motion" instructions. It wasn't specific enough for him to recover well and spent his entire life reaping the results of my uneducated decision...
I clearly still feel guilty...but I hope you get my drift :-/