Have you seen a chiropractor? My Dr. says nothing can be done about one leg being shorter than the other. But, I went to my chiro and he said that is not true. it is usually cause by muscles shifiting and pulling. A bone scan won't pick that up. He does a quick little massage thing on my back and buttocks, and I walk out with my legs the same length again. It doesn't last long right now, but he repeats it every week, and says if I get healthy, and don't develop more muscle issues he may be able to get it to stay that way.
Just my two cents. Hope it helps.