Partial or total knee replacement surgery aims to restore stability to a worn or damaged knee by removing and replacing bone fragments that form the knee joint with artificial implants.
These implants typically last about 20 years in 90% of recipients. When the implants are no longer functioning correctly, a knee replacement revision surgery is often needed and may involve:
- Reshaping bone
- Removing bony fragments
- Realigning the original implant
- Replacing the original implant with a new one
What Would Cause a Knee Replacement Failure?
Though a total knee replacement is one of the most effective procedures in modern medicine, over time the replacement may fail for many reasons, including:
- Instability (loose ligaments holding the knee stable)
- Implant dislocation
People with failed knee replacements may experience pain. Their knee may become swollen and stiff, making it difficult to walk and carry out daily functions.
Is Knee Revision Surgery Safe?
Approximately 22,000 knee replacement revision surgeries take place in the U.S. annually — half of which occur within two years of the original knee procedure.
This procedure can be complex and challenging for both the recipient and surgeon, especially if the original implant must be removed. In these cases, depending on the length of time, the implant may have grown into — and become attached — to existing bone. This means that once the original implant is removed, there's less bone left behind.
Revisions are more prone to complications and don't provide the same 20-year life span as an original surgery. This is typically due to:
- Scar tissue
- Increased surgical time
- Potential poor blood supply to the tissues and bone
Also, the risk of infection with knee replacement revision surgery is four times greater than the original surgery.
How Does Your Doctor Determine if Revision Total Knee Replacement Is Needed?
If you're experiencing difficulty or pain with your knee replacement, you should ask your doctor to examine it. Your doctor will likely order imaging tests and X-rays of the area around the knee implant. The results will help your doctor determine the extent of the issue with the knee implant by looking for any position changes, loosening, and bony fragments. An MRI or CT may be scheduled to see other components — like tissue damage — that can't be seen on X-rays.
To rule out infection and other blood illnesses, lab tests will be ordered. This could include a traditional blood draw or even aspiration of the knee. During aspiration, joint fluid is drawn from in and around the knee. This fluid is then examined in a lab to check for certain disease processes.
What Happens During Knee Revision Surgery?
How knee revision surgery is performed depends on the reason you're having the procedure. Here's a look at what typically happens in a few common situations.
Knee replacement revision surgery for trauma or fracture. Fractures are broken bones around the implant used in the knee replacement. Your surgeon must determine the correct way to enter the knee cavity and remove the damaged fragments. They must then reconstruct the knee joint line and shave, smooth, and reconstruct the posterior condylar offset — the back thickness of the femur bone shaft.
Knee replacement revision surgery for infection. In some cases of infection, bacteria can be washed out, antibiotics given, and metal implants can be left in place. Otherwise, the implant must be removed, infected body matter must be cut out or debrided, and a spacer must be placed until the area is clear of infection. At a later date, your surgeon will insert a new permanent implant.
Knee replacement revision surgery for dislocation. Wear and tear leading to loosening can easily occur over time. In a process called aseptic loosening, the connection between the bone and implant breaks down as the body rejects the foreign particle. Usually, removal of loosened bone particles, medication, and repositioning of the implant helps this complication.
Knee replacement revision surgery for instability or stiffness. Ligaments around the knee can become loose and unstable. Sometimes treatment can be nonsurgical, like physical therapy and bracing. Otherwise, soft tissue tightening can improve stability. Sometimes scar tissue can limit the range of motion, causing stiffness. Your surgeon may place you under anesthesia and attempt to break up scar tissue around the knee during the procedure. If the scarring is too extensive, revision surgery to get rid of the excessive scar tissue may be needed.