Most people who have knee replacement surgery feel or hear clicking when the knee is bent or when walking, according to the American Academy of Orthopaedic Surgeons. This clicking comes from the metal or plastic of the replacement knee and usually lessens over time.
Sometimes it is necessary to have a doctor assess the noises coming from the knee replacement, reports About.com. Since the noises coming from a knee replacement often decrease, a new noise should be evaluated. Also, if the noise is accompanied by pain or swelling in the joint, the patient should visit the doctor. Noises may also result from the tendons or fluid around the knee.