Risks from knee replacement surgery include infection, blood clots in legs or lungs, stroke, nerve damage and heart attack, according to Mayo Clinic. Healthline states that serious complications are only present in about 2 percent of knee replacements.
More extensive risks include complications from a transfusion, allergies to metal components used in artificial knee joint, slow-healing wounds that cause bleeding complications, injuries sustained to arteries or nerves, loss of motion in the knee and implant failure, notes Healthline. Implant failure can be caused by the artificial kneecap not bending properly. Revision surgery can be performed to correct implant failure, infection, knee stiffness, instability and continued pain.