I would try Promaxol to reduce the pain and help healing to begin. Promaxol would be a good choice for your dog. It contains the stronger LM potencies. After improvement is seen then you can switch over to Arthro-IonX. In addition it is helpful to give Canine Probiotics with each meal, Omega 3,6,9, MSM, and vitamin C daily. (We carry the first two and the other two you can get at a health food store.) The oligotherapeutic mineral base found in the IONX products helps the body to better utilize the other nutritional substances given for a synergistic response and faster healing. Also be sure to give sufficient fresh water that is free of chlorine and fluoride. If you can gradually phase into a grain free diet that can be helpful too. The other thing that is sometimes beneficial is to have a certified veterinary chiropractor check for spinal alignment and make any corrections as necessary. I think this is important in your case with severe wearing of the joint.
Please let us know how you progress or if you have any other questions.