My mother has severe pain in her hips, ever since she underwent hip joint replacement surgery. She is now unable to even walk normally. Will this become permanent?
You need to follow up with the surgeon and have that conversation.
That is an unexpected result, and repeat evaluation, or second opinion would be warranted to make sure there is not a treatable cause of her continued pain. Workup would involve repeat xrays, possible lab work, physical exam. Evaluation sooner rather than later would be recommended to avoid it becoming a permanent problem.