Hi, I went through the same thing. I had some discomfort for awhile but it was more noticeable 2 years ago. The surgeon said my prosthesis was fine (x rays, bonescan) and suggested seeing a back dr. which I did. I had some PT, MRI--no impingement and was referred to a physiatrist who did an emg, nerve conduction study, had more PT and things did not get better and the pain was getting worse. He was really confused so he ordered another bonescan of the leg and MRI of my back. The bonescan finally showed that the the whole thing was loose and broken about an inch from the broken!
It upsets me that I've been in such pain and discomfort for so long when I figured it was my prosthesis that was the problem.