I am a 54 year old male, and I received total knee replacement in 2002. From that time to about the beginning of 2006, I did quite well with normal leg motion. After that time my knee began to swell and I began to experience pain. The pain increased to the point that I was put on pain killers (narcotics, non-narcotic analgesics) with the entire available anti inflammatory and related treatments (mobic, vioxx, celebrex, bextra, et al)  tried to no avail. The pain killer would work for a time, then lose their power, tempting me to increase the dose. All the while my knee has gotten at least twice the size of my other knee. It is difficult for me to believe that all of the pain killers available begin to decrease in their effectiveness after just a short time.
  Recently my Ortho did a fluoroscope which revealed wear on the plastic part of the replacement. He removed some plastic particles that were floating around, and cleaned up some scarring tissue. After this procedure, which included draining of the fluid, I experienced some relief (outside of the normal pain associated with the surgery itself). After a short period the swelling returned with the conditions seemingly slightly worsened.
  I have had bone density scans which showed no deterioration, sonograms which showed no blood clots, tests run on the fluids which showed no infections or abnormalities, etc. Xrays have shown that the parts are stable, as did the scope.
  Are these tests conclusive? Can the joint still be loose? How can this be tested before major invasive surgery to investigate? Could something else be causing the pain and swelling?