Thank you so much for helping your grandma search for answers, but it also brings up questions at the same time. If you have not talked with her doctors yet, that would be the best place to start, the doctor that wrote her the "blood thinner" prescription in the first place. In the mean time, maybe try a heating pad or ice backs to see if either of those might give her some relief. The questions would be is it arthritis or something else? Blood thinners are usually given to people that have circulatory problems like blood clots, strokes or heart problems. The pain in her legs could have something to do with that and not be arthritis at all or combination of both. If her legs are swelling or retaining water then of course get her feet up and contact her doctors right away. Her leg pain could be from lack of use to combined with arthritis, so hard to say of course, but Blood Thinners puts this back to the doctor whom prescribed them for her. Wish you so much luck and hugs to you and grandma both