<s>[INST] I had a medial PKR 8 years ago. The xrays show it is still intact and not worn. My leg hurts below the implant and I have pain on the medial side of my knee. I m not sure what this pain can be from. Do xrays detect everything? I ve done lots of backpacking so the PKR held up well. I have lots of pain under the knee cap and on the lateral side of the leg. I can walk for an hour then have to stop due to pain. Sunrise views show both kneecaps are touching the femur and are off center. I believe it is time for a TKR. Are there reasons for a TKR that aren t visible? The xrays don t show it is bone to bone. A doctor says it s time for a revision and my knee really does hurts and limits my activities. I m 62 not fat. [/INST] Dear Patient, Welcome, and thanks for sharing your concern I went through your query, and I feel, you are aware that medial side pain along the joint line is very common with degenerative arthritis, and thus osteoarthritis cannot be ruled out. The x-ray in such cases may not give the whole picture, but is quite good at showing the changes in the joint that may occur as a result of osteoarthritis. So get yourself an x-ray done at the earliest. I hope my advice would have been useful, in decision-making regarding your treatment, still if you have any clarifications or doubts feel free to contact back. Thanks </s>