Hi Peggy,
I'm not sure what 'LR' leg means, but to relieve pain from old fractures, I find Symphytum very effective. If you can't source it as a herb, the homeopathic version works well. I'd try 30C once to twice daily for a few weeks.
In addition, if it's a hind leg, and GB points relieve the lameness, I'd look at Xiao Chai Hu Tang as an option for preventing further crises and getting the dog off pred. If the dog is dry as well, then you can combine about 65g of Xiao Chai Hu Tang with 35g of Si Wu Tang, which is a Blood and Yin tonic.
If the dog looks more Damp, then Si Miao San is an option. You can enhance the anti-Addisonian activity of the formula by adding Corn Silk.
Lastly, Yin tonics are advocated in the human literature for Addison's disease, presumably because of the volume contracture that can occur with time. The typical recommendations don't have much biomedical basis for their activity but if you select a Yin tonic that has Wu Wei Zi (Schizandra) and Ginseng in it, then you can expect it to be more helpful in allowing you to wean off prednisone.
Hope this helps you out,
Steve