My 11 Y.O. Newfie/Lab Mick had his surgery 6 months ago and is now back to full throttle. They also removed the meniscus. Daily glucosamine/chondroitin pills from Costco. He gobbles them like candy. His deal cost $1100 total. Worth every penny for me. No more frisbie playing or heavy swimmig at the lake. That's what did it. A partial tear that I overlooked. I don't believe they ever heal anyways.
There is some remaining early moring stiffness, but he's no longer shy of joining the other dogs in a trail romp. Family down the street has a chocolate lab that needed it but they refused. Now in later life he struggles to walk for a drink and to 'go outside'. Can't do stairs or be a dog any more.
The best preventative is to keep their weight low. I now feed 3 times a day and they have all dropped the weight 20%. The vet is surprized by the amount. No more chicken strips (the ones from china have been id'd as poisonous, anyways), no more dishwashing and I switched to maintenance food, apples, carrots and fresh horse poop.