A year ago today our Black Lab, Nikki, underwent surgery to have her canine cruciate ligaments repaired in both rear knees after having ruptured them. It was rough day for the wife and me and I'm glad it's well behind us.
Nikki's been doing excellent since the surgery. Other than a slightly strange gate (which is only really noticeable if you're looking for it) you would never know she had both knees replaced. Last summer she enjoyed many a days running and playing ball in the backyard. Occasionally the knee would "give out" on her when she'd try to make a quick cut and she'd come up limping, but I think she limped only because it felt foreign because within minutes she was back to running and jumping at full speed.
It's amazing to me everytime I see her run around the backyard or jump around that a year ago she could barely walk. While the surgery was costly, we're just glad we got our dog back. :)