How to relax stiff limbs especially crossed legs while on bed, even for cleaning?

Mom Has been bed ridden for almost one year. I do everything to help relax stiffened muscles. Difficult during diaper change when she just presses her arms over her torso and her elbow is strongly in the way, (it hurts every time also!!!)and being crossed legs always I have to pry the legs open to do that. All the more while lifting her up to wheel chair and to bath or groom. I am fully aware that she can't help it, so want to find some way to do that in a win, win situation. She had undergone hip replacement surgery on her left side, so have to do it gently which is not gentle on my shoulders. Massaging her back, arms legs etc works a little bit. I do it with oil during her bath days. HELP!