how old is she? are you certain its arthritic issues? has she seen a Vet? there are some prescription meds they can prescribe but you need to know for sure what is causing the pain....
Walking on the hocks is a sign of weakness! She could have a number of conditions such as diabetes, kidney disease, or other electrolyte abnormalities. You should have your veterinarian take look at her and run some blood work ASAP!