I just went through hip replacement surgery in November. I took slept in my side but with recovery from surgery, you out pillow between your legs if on side. So as not to go above 90degrees. I slept in my sisters couch and put pillow on outside of legs so it would not turn or rotate out.
The physical therapist and occupational therapist go over that with you. I had pre-op class on surgery which helped me practice before class. Hope this helps.