18 June 2024
Knee replacement surgery significantly improves the quality of life for many patients by alleviating chronic pain and restoring mobility. Thanks to advancements in implant designs and surgical techniques, knee replacements typically last 15 to 20 years for over 85% to 90% of patients. However, younger individuals who undergo knee replacement may require a revision surgery later in life to address implant failure or other complications. This guide explores the causes of implant failure, risk factors, symptoms, treatment options, and the revision surgery process.
Revision knee replacement surgery, also known as knee revision surgery, involves replacing or repairing an existing artificial knee joint. This procedure is more complex than the initial knee replacement, requiring specialised skills and experience. The need for revision surgery can arise due to several factors, including implant wear and tear, infection, instability, or mechanical failure.
1. Implant Removal: The surgeon removes the existing implant and assesses bone quality.
2. Bone Grafting: If there is significant bone loss, bone grafts or metal components may be used.
3. New Implant Placement: The new prosthesis is positioned to ensure proper alignment and stability.
4. Closure: The incision is closed, and a drain may be placed to manage fluid buildup.
The primary causes of knee implant failure include:
1. Implant Wear and Tear: Over time, the materials used in knee implants can loosen due to wear and tear, high-impact activities, excess weight, or the body's reaction to tiny particles produced by joint friction. These particles can cause the bone to break down in a process called osteolysis, leading to implant loosening and bone weakening. This is one of the most common reasons for revision surgery.
2. Infection: Post-surgery infections, though rare, can occur. Bacteria may form biofilms on the implant surfaces, making them resistant to antibiotics. Infections around the implant can cause severe pain and swelling, necessitating the removal and replacement of the prosthetic.
3. Instability If the knee joint becomes unstable or dislocates, revision surgery can restore proper alignment and function. This occurs when the soft tissues around the knee fail to provide adequate stability, often due to increased laxity or improper positioning of the implant. Pain and the sensation of the knee "giving way" are common symptoms.
4. Mechanical Failure: In some cases, components of the implant may break or loosen, requiring surgical intervention.
5. Leg Fractures: Fractures near the knee implants can disrupt implant fixation and stability, necessitating revision surgery.
6. Stiffness: Excessive scar tissue can limit the knee's range of motion, impacting daily activities. Manipulation under anaesthesia or revision surgery may be required to regain mobility.
Revision knee replacement surgery is typically more extensive than the original procedure. Here’s a step-by-step overview:
1. Preoperative Assessment: Before surgery, your orthopedic surgeon will conduct a thorough assessment, including imaging studies like X-rays or CT scans, to determine the cause of the problem and plan the surgery.
2. Surgical Approach: The surgeon will make an incision to access the knee joint, remove the old implant, and assess the condition of the bone and surrounding tissues.
3. Implant Removal: The damaged or worn-out implant is carefully removed. In cases of infection, the area is thoroughly cleaned and treated.
4. Bone Grafting: If significant bone loss has occurred, bone grafts may be used to rebuild the structure before placing the new implant.
5. New Implant Placement: A new prosthetic knee joint is positioned, ensuring proper alignment and stability.
6. Closure: The incision is closed, and the knee is bandaged. A drain may be placed to remove excess fluid.
Several factors can increase the likelihood of implant failure:
● Age and Activity Level: Younger, more active patients exert more stress on their implants over time, increasing the wear and tear
● Obesity: Higher body weight leads to increased wear rates and a greater risk of infection.
● Previous Knee Surgeries: Past surgeries raise the risk of infection and implant failure due to scar tissue and changes in knee anatomy.
Symptoms indicating a failing knee implant include:
● Persistent pain and swelling
● Reduced joint function
● Knee instability
● Stiffness
Postoperative care is like that of the initial knee replacement, including:
1. Hospital Stay: Patients typically stay in the hospital for a few days post-surgery for monitoring and initial recovery.
2. Physical Therapy: Rehabilitation is crucial. A tailored physical therapy program will help restore mobility, strength, and function. Begins within 24 hours and continues for up to three months to restore mobility and strength.
3. Pain Management: Effective pain control strategies, including medications and possibly nerve blocks, will be implemented to manage postoperative pain.
4. Regular Monitoring: Regular follow-up visits to ensure proper healing and to address any complications promptly.
Recovery time varies, but physical therapy typically lasts up to three months. Patients may initially use assistive devices like walkers or crutches, gradually progressing to walking without assistance.
Revision surgery carries risks, including:
● Infection
● Bleeding
● Nerve or blood vessel damage
● Blood clots
● Intraoperative fractures
The complexity of revision surgery increases these risks, which can be minimised through careful surgical planning and techniques.
Revision knee replacement surgery is a critical procedure for those experiencing issues with their initial knee implants. With advancements in surgical techniques and prosthetic materials, many patients can enjoy renewed mobility and pain relief. If you suspect your knee replacement is failing, consult with a qualified orthopaedic surgeon to explore your options and achieve the best possible outcome.
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