Revision knee replacement

Revision knee replacement

Revision knee replacement is a form of surgery that will be conducted to fix or reconstruct a failed or damaged primary knee replacement. During the traditional knee prosthesis, the destroyed knee joint is replaced through metal and plastic pieces. In later stages, these may loosen over time, wear out, or become infected, and may cause pain, instability, or loss of functionality.

Revision surgery may involve just part of the prosthesis, or it may involve all three major components of the knee (the femur, tibia, and patella). In some cases, it is necessary to rebuild the bone with the help of metallic augments or by means of bone grafting before the application of the new implant.

Symptoms of a Failed Knee Replacement

The most common sign that a knee replacement has failed is persistent or severe pain, particularly when caused by infection or loosening of the implant. Other signs and symptoms can be :

• Swelling around the knee
• Redness or warmth over the joint
• Joint stiffness and reduced range of motion
• A feeling of instability or a limp when walking

In cases where the bone around the implant is damaged, standard knee replacement components may no longer be suitable. Surgeons may use specialized, longer-stem implants that anchor deeper into the bone for improved stability.

Indications for Revision Knee Replacement

Revision knee replacement is typically more complicated than the initial procedure, often demanding thorough preoperative planning and the use of advanced, specialized surgical tools. Common reasons for revision include :

• Loss of knee stability or function
• Increasing or persistent pain
• Infection, which may present with signs like redness, swelling, fluid discharge, or pus formation.
• Fractures involving the bones supporting the implant
• Implant wear or breakage over time

In some cases, tiny particles from the worn prosthesis can accumulate around the joint, triggering inflammation and further damage.

Common Causes of Revision Knee Replacement

Infection

One of the major causes of revision in knee replacement is infection, which constitutes about 25 % of the total cases. Once the bacteria enter the zone around an artificial joint, the painful experience and decreased mobility may become acute.

If the infection is deep or persistent, revision surgery is often performed in two stages:

• Stage One : The infected implant is removed and replaced with a temporary spacer loaded with antibiotics. This spacer preserves joint space as well as provides targeted medication to the infected tissues.
• Stage Two : After 6–12 weeks of antibiotic treatment, a new implant is inserted.

Mechanical Loosening

During a primary knee replacement, a metal base is typically fixed to the tibia using a high-strength bone cement called PMMA (polymethyl methacrylate). With time, the connection between the bone and the implant can deteriorate, leading to loosening of the prosthetic joint.

Mechanical loosening results in pain, difficulty walking, and reduced stability. Regular X-rays are used to monitor the attachment and detect loosening early.

Instability

Achieving proper balance of the soft tissues around the knee is crucial during surgery. If the tissues are too tight or too loose either initially or over time the joint may become unstable. This can lead to abnormal wear, dislocation, or subluxation (partial dislocation).

Instability can also result from trauma or fractures that disrupt implant fixation. In such cases, revision surgery restores alignment, balances the soft tissues, and provides a stable platform for weight-bearing.

Preparation for Revision Knee Replacement

Each revision surgeries are different as there are different causes of implant failures.  Preparation typically involves :

• Blood tests to check for infection
• CT or MRI scans to assess bone loss
• X-rays to evaluate implant positioning and alignment

Revision knee replacement carries higher risks than the primary surgery. It often takes longer to perform and requires greater surgical expertise due to:

• Scar tissue from the original surgery
• Reduced bone stock
• Difficulty in protecting surrounding blood vessels and nerves

It is important to note that a revised knee rarely performs exactly like a primary knee replacement, and recovery can be more challenging.

Postoperative Rehabilitation

Recovery after revision knee replacement is similar to the primary procedure but may take longer due to the complexity of the surgery. Postoperative care includes :

• Blood thinners to prevent blood clots
• Pain management with medications
• Physiotherapy to restore mobility and strength
• Walking aids such as a walker or crutches in the early stages

Patients are usually monitored closely for at least three months and continue physical therapy to maximize the function of the revised knee.

Key Takeaways

• Revision knee replacement is a complex but highly effective procedure for addressing failed primary knee replacements.
• Common causes include infection, implant loosening, and instability.
• The surgery requires thorough preoperative planning and is best performed by experienced orthopedic surgeons.
• Recovery can be longer, but with proper rehabilitation, most patients regain significant mobility and pain relief.