[rosiedog]

This is most likely a torn cruciate ligament, which creates an unstable joint. If you have the finances, surgery is absolutely the best option to re-create the stability. Use the Rimadyl. It is a very good pain killer and is an anti-inflammatory, to help in the knee joint. Hill's J/D and Royal Canin Mobility Support are loaded with excellent supplements, but they are not an alternative to surgery, they help with joint healing, and limit joint damage. Another excellent option is Cartrophen or Adequan. These are injections that you can do at home. Google Cartrophen. It has very impressive results. Keep activity restricted to leash walks only, because right now the other leg is at risk of doing the same thing. No twists and turns! Good luck.