What Are the Symptoms of a Failing Knee Replacement?

Knee replacement surgery can be a life-enhancing procedure for those who suffer from chronic, disabling end-stage arthritis. Quality of life can be improved immensely, and return to near-normal function and to activities of daily living are major goals of this type of surgery. Infection, implant loosening and knee cap dislocation can cause your knee replacement to fail. See your surgeon if you experience symptoms of a failing knee replacement.

Someone has had a knee replacement. (Image: Jodi Jacobson/iStock/Getty Images)


When prosthetic components begin to fail, issues such as fracture of the plastic spacer located between the metallic thigh bone and shin bone implants can occur from abnormal wear patterns or improper surgical techniques. Plastic fracture fragments can dislodge and become stuck between these surfaces, causing pain and mobility problems. Pain can begin as a mild soreness, or it can be severe if the fracture of the plastic occurs suddenly.


Swelling occurs as a result of inflammation of the lining of the knee, which in turn stimulates production of fluid. This is the body's response to irritation, causing swelling in your knee. This irritation is frequently caused by the presence of microscopic pieces of plastic in the knee fluid, as well as the instability caused by loosening of the joint.


Instability in the knee often feels like the knee wants to give out with standing or walking. This is frequently caused by excessive wear of the plastic spacer, causing it to be thinner than it was at the time of surgery. Ligaments become loosened, making your knee joint less stable.


In addition to the swelling that can occur, another symptom of a failing prosthesis can include noticeable warmth of the joint. Replaced knees can exhibit warmth in the joint for months after surgery, but this effect steadily decreases over time. The warmth associated with prosthetic failure can often be significant and associated with a level of redness of the skin caused by inflammation.

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