The kneecap, or patella, is the bone that covers your knee. Over time, scar tissue builds up inside the knee, causing the knee joint to shrink and tighten. Revision surgery can be difficult because a failed knee implant can damage the bone and tissue around a replaced joint.
This irritation is frequently caused by the presence of microscopic pieces of plastic in the knee fluid, as well as the instability caused by loosening of the joint.
I know the feeling very well as my knees also will make the same noises or sensations that others feel from time to time. The warmth associated with prosthetic failure can often be significant and associated with a level of redness of the skin caused by inflammation.