I had a knee replacement 5 yrs ago. It is a Stryker product. I had an episode of sudden swelling, a popping, feeling in back of knee, and unable to bear full weight on the left leg. Went to the ortho MD. He did xrays that he stated show no change in the prosthesis. I still have pain, and weakness in the knee, and swelling in the knee and ankle. He stated my quads are very weak, and i need PT. Something seems wrong, but the MD doesn t feel there is.