My cocker, Remy, had the first type of surgery on one of his rear legs about 6 years ago now. He's fine now, and the leg is as strong as the uninjured one. He's 13 and has terrible arthritis in his hips, for which he has regular acupuncture treatments, but the knee is good.

One thing about the recovery--for several weeks, the dog can not walk up/down steps or walk much at all, and must be crated most of the time. That's fine when your dog is like Remy, about 35 pounds, but I know people with larger dogs who had a very difficult time carrying the dog down the steps to go outside. I built a ramp on my front steps but it was too steep and Remy wouldn't use it. Also, Remy would sneak around and jump up on the couch when I wasn't watching and his recovery went slowly, so we went to a dog swimming pool (one of the advantages of living in a city--we've got access to EVERYTHING) a couple times a week for a month or so and that strengthened his leg.

Good luck!