Yes. Glucosamine works. Loki is on it twice a day. He has a grade 2 LP on one side. The vet recommended this as the only treatment. She suggested Loki not to agility or jump off of high beds, but he's fine on stairs and the couch - basically anything he can jump ONTO is ok to jump off of. We are not restricting his activity, since he's a Yorkie and that's impossible!
Anyway, I have not noticed many problems with his leg since starting him on it. I believe it also helps long term - so that they do not develop arthritis.