Five reasons knee replacements can fail

NEW YORK, July 16 (UPI) -- Most knee replacements work well for years, but a U.S. surgeon says sometimes they can fail due to friction, infection, instability, fracture or stiffness.

Dr. Amar Ranawat, a hip and knee specialist in the adult reconstruction and joint replacement division of the Hospital for Special Surgery in New York City, says knee replacements normally perform well for at least 15-20 years in more than 95 percent of patients.

However, there are times when replacements fail and patients will need a corrective procedure known as revision total knee replacement. Friction -- joint surfaces rubbing against each -- Ranawat says, can result in bone loss and loosening of the implants.

"A failed knee implant is usually caused by wear and tear with subsequent loosening of the implant. Other causes are infection, instability, fracture, or stiffness," Ranawat says in a statement.

The sensation of the knee "giving way" can occur because the soft-tissue surrounding the knee is too weak to support standing and walking or because the implant was improperly placed. Stiffness means loss of range of motion and can result in pain and loss of function.

Increased pain or decreased function are signs of implant failure. There can be swelling and stiffness either across the whole knee or in a small section, Ranawat says.