Painful or Failed Total Knee Replacement
A modern total knee replacement in a patient over the age of 65 of normal weight and activity should last them 20 plus years. However, a number of total knee replacements will fail within the lifetime of the patient. Sometimes this is expected failure, and sometimes unexpected.
The knee replacement consists of metal and plastic components. It is easy to understand that the plastic, being the softer material will wear at a faster rate than the metal. This is normal wear. In older knee replacements the wear of the plastic caused a reaction in the body creating damage to the surrounding bone. This is called OSTEOLYSIS. When this occurs, the metal implants can gradually work loose, or the bone can break or fracture.
New plastics wear far less and when they do they no longer cause the same amount of bone loss.
Sometimes the cement used to hold the metal to the bone can fail to hold the implant after a period of time and the metal implant begins to move slightly causing pain.
These two types of loosening are termed ASEPTIC LOOSENING. i.e. there is no evidence of infection.
When there is infection involved, which causes damage to the bone, it is termed SEPTIC LOOSENING. This is a Prosthetic Joint Infection or PJI. Thankfully this is a rare occurrence.
Sometimes the plastic in the knee can break following wear, sometimes the plastic can come loose from the underlying tibial tray, displace into the joint and cause locking. This is called DISLOCATION.
All of the above situation tend to involve a painful knee replacement. This can be gradual or sudden depending on the underlying cause of the failure.
Dr. Thornton-Bott has a lot of experience in managing failing knee replacements. At the consultation he will take a history from you to identify your pain and the likely cause. He will arrange specific laboratory tests and scans to identify if the total knee replacement is loose, failing and if so whether there is an underlying cause such as infection. Once he has the results he will then discuss with you the best management plan for you.