The metal and plastic parts that make up the total knee prosthesis wear out over time due to the friction that occurs during movement. With the body’s response to metal and plastic parts that are too small to be seen and caused by abrasion, the prosthesis can be separated from the bone to which it is attached and loosen. The lifespan of knee prostheses made using appropriate surgical techniques and modern prosthetic designs has now extended up to 15-20 years. Loose prostheses can be removed with a second surgery and placed again in most patients, but the life of the second prosthesis is not as long as the first. Sometimes prosthesis loosening may be accompanied by bone loss.
This can make the surgery even more difficult.