Good evening @@abmjr, I am quite concerned about a 12-year-old TKR that causes pain but doesn't reveal the reason for it. May I suggest that you review this youtube display of what is called Chronic Myofascial Pain Syndrome. The fascia forms on our body parts in layers.....and when they stick together, you can feel a burning pain.

The solution is MFR (myofascial release therapy) a form of hands-on therapy that releases the fascia and lets it move freely in the joint area. Once you have watched this film you may want to see a demonstration by John Barnes on the MFR site.
https://www.myofascialrelease.com/about/
Let me know if you have questions or concerns that I can help you with relative to your specific issues. By the way.....where do you live? We can try and find an MFR therapist near you who can sit down with you for a chat.

May you be free of suffering and the causes of suffering.
Chris