My hip replacement and subsequent revision surgery was 3 years ago. The last PT I worked with discharged me after 6 sessions and told me that he did not know why I walk the way I do and that there was nothing more he could do for me. I decided that I would continue to do my own re-hab doing the exercises I was given and working out at the gym. At 3 years post surgeries, my hip is good and my leg works OK. I know that it is weaker than prior to surgery. I use a walker now because I am unstable walking. (I also have neuropathy which is not helpful for walking and balance etc. and do exercises for those issues as well.). I have learned two things which may be helpful for your sister. One is to work toward the pain and to not give up. The second thing is I have learned acceptance. It is difficult sometimes. I named my walker "PITA". most know what that stands for. A little humor goes a long way. I have a dear friend with ALS which helps me put my problems/issues in perspective. I wish your sister the best and am sending tons of support.