What is a revision knee replacement?

Knee replacement surgeries are very successful at relieving pain, restoring mobility and improving function for patients with knee arthritis. Currently, over 500,000 total knee replacements are performed in the United States each year. Now that our population is living well into their 70s and 80s, it has been projected that more than 1.3 million knee replacements will be performed in 2030! Despite great results, a knee replacement may need to be re-done (revised) when certain parts wear and/or give out over time. Signs may include increasing pain and swelling in addition to stiffness and catching. If you experience any of these issues or concerns, you should talk with your surgeon.

What are the causes of knee revision surgery?

1. Infection is the most common reason for a revision knee replacement. Infections may develop right after surgery or years later if the infection travels from another part of the body. An infected knee replacement is a BIG DEAL. Bacteria like to stick to metal implants and can be hard to remove, which is why surgery and IV antibiotics are usually necessary to help your body fight the infection. The average risk of developing an infection is between 1-2%. Typically, patients with more medical issues are more prone to developing an infection compared to those with fewer medical problems.
2. Loosening is the next most common reason for revision knee surgery. Over time the components can wear down, break and/or become loose from their attachments to the surrounding bone. Patients may complain of repeated swelling of the knee and/or pain when bearing weight through the joint. Therefore, it remains important for patients to have their knee replacements periodically checked to ensure things are in good working condition.
3. The alignment of the original knee components can change over time or the soft tissues around the knee may stretch out leading to feelings of instability. An unstable or unbalanced knee replacement can lead to pain and affect balance and function. Patients may complain of subtle feelings of shifting within their knee or experience a sensation where the knee wants to buckle or give way during certain activities. The extent of the instability will factor into what needs to be done during revision surgery.
4. Wearing of the plastic liner situated between the thighbone and shinbone represents another cause of revision surgery known as polyethylene wear. The small pieces of worn plastic can excite the immune system and lead to knee joint instability and loosening of the prosthesis over time. Thankfully, today’s knee replacements use plastic liners that are more wear resistant.
5. A fracture (break) in the bone around the knee replacement from a fall or trauma can cause issues with your knee replacement. Depending on the location of the break, some of the implants may need to be replaced if loose or out of position. The bone may need to be stabilized with plates and screws to fix the fractured bone so it heals appropriately.

Adapted from 2021 American Joint Replacement Registry, American Academy of Orthopaedic Surgeons

What does revision surgery entail?

A revision knee replacement is a more difficult procedure compared to your original surgery. Therefore, this type of procedure should be performed

by an orthopedic surgeon experienced in revision surgery. Some patients require a partial revision where just one or two of the components (femur, tibia, liner or kneecap) are replaced while other patients need a full revision where all the components are exchanged. Revision surgery may require your surgeon to use special implants.

During a revision surgery, a larger incision is generally required to access the old implants and make room for the new ones. The buildup of old scar tissue can make removal of the old implants more challenging. Next, if a component is well-fixed to the bone, it must be carefully freed from the bone. The goal is to remove the component without damaging the underlying supporting bone. If the component was cemented in place, the remaining cement will need to be removed as well. Specialized instruments are available for these tasks allowing surgeons to remove implants in a timely and safe manner.

Your surgeon determines which revision implants are needed to address the problem after assessing the remaining bone and soft tissues. Revision implants are usually larger than original knee components to help ensure the new components are anchored well to the surrounding bone. The new implants are then usually cemented into place. A new plastic spacer is used to fine tune the stability of the knee revision.

Left: X-ray of primary knee replacement; Right: X-ray of revision knee replacement. Note the long stem attachments needed to help anchor the new implant to the bone.

How is it different than my first surgery?

Compared to an initial surgery, revision procedures:

• Often take longer. A second surgery may require removing all the original implants, preparation of the bone and then placement of the new implants, meaning more time is needed to safely accomplish tasks.
• Have higher risks.
• May require restrictions during your recovery.
• Are generally more complex. Healing may take longer compared to your original knee replacement. The length of recovery from a revision knee replacement depends on your medical issues, the extent of the revision surgery and your physical therapy afterwards. Usually, the recovery from a revision knee procedure takes about 3-4 months. However, some studies have shown it can be between 1-2 years before fully recovering from your knee revision surgery.

Since revisions are longer and often more complicated, the long-term results may not be as good as the results from your original surgery. Most patients can expect a reduction in pain and a more stable knee after revision surgery.

Most knee replacements will function well for 15-20 years; however, over time your knee replacement may require a revision surgery (“tune up”) to keep you mobile and functional.  There are several reasons for revision surgery including infection, loosening, instability, wear, and fracture. Remember that revision surgeries are longer and more complex compared to your original surgery. As a patient, you need to feel comfortable with your surgeon. Revision surgery can be complicated therefore it is important that you have a good understanding for why a revision surgery is necessary. Do not hesitate to ask questions. Your surgeon can further explain the risks, benefits and expected recovery time for your revision procedure.

If you have a painful or old knee replacement, please call for a Marshall Orthopaedics at 304-691-1262 for a consultation. No referrals are necessary.