Whew. Parker is just fine.
The surgeon said everything went very well. She reported he completely tore his meniscus and his right CCL (the doggy equivalent of a human's ACL), and it looked like the result of an acute injury, not age-related deterioration. This is good news because it means he has a much lower risk of doing this to his left leg than we worried about.
He's recuperating from the operation right now and will remain overnight for observation. He should be home after lunch tomorrow, with a healthy quantity of drugs and probably a really sharp appetite.
Recovery should take 6-8 weeks, though he should be able to go for actual walks within about 2 weeks. But wow, he's not going to like those two weeks.
Stay tuned. Photo tomorrow, I expect.