Hey. Thanks for writing at HCM.
At this age its common to lose an excess amount of sodium or electrolytes from the kidneys. And there is water retention in limbs
because of prolonged standing or sitting. For that reason it is advised to keep the legs above the level of body. But after hip surgeries exercises of hips are required too, But she doesnt have to exercise the whole day. Let her electrolytes come back to normal level and then she can do those exercises regularly. Till then let her lie down with legs elevated and make her walk every once in a while. Make her shift her position in bed as well. Hope this helps. Take care