Anyone whose prosthetic knee implant fails due to fractures or wear (indicated by loosening of the prosthetic components) may need to undergo a revision procedure. Newly developing knee pain and swelling may be an indicator of a loose and unstable prosthetic component or an infection. In some cases, the knee may develop an excessive amount of scar tissue, which limits how much the joint can move. This causes stiffness, which is an indication you need the surgery.