Knee revision surgery is a procedure undertaken when a previously implanted artificial knee joint, known as a prosthesis, no longer functions correctly. This involves replacing some or all components of the original knee replacement with new ones. While the initial knee replacement aims to alleviate pain and restore function, a revision surgery becomes necessary when the implant wears out, becomes unstable, or experiences other complications over time. It is a more involved and less common operation than the primary knee replacement.
The Leading Cause of Initial Knee Replacement Failure
Aseptic loosening stands as a common reason for initial knee replacement failure, particularly after 10 to 15 years. This condition involves the detachment of the implant from the surrounding bone without infection. It frequently arises from osteolysis, a process where tiny particles, primarily from the plastic (polyethylene) component of the implant, are released into the joint due to mechanical wear. These debris particles trigger an immune response, which, over time, can lead to the breakdown of bone tissue around the implant, causing it to loosen.
Patients experiencing aseptic loosening may notice pain, especially during weight-bearing activities, along with swelling, stiffness, or a feeling of instability in the knee. Several factors can contribute to this loosening, including the wear of the polyethylene spacer, bone loss around the implant, and even the progression of underlying arthritis.
Other Factors Necessitating Revision
Beyond aseptic loosening, other issues can lead to the need for knee revision surgery. Periprosthetic joint infection (PJI) is a serious complication and is a frequent reason for early knee revisions. These infections can occur at any time, from shortly after surgery to many years later, and often require surgical intervention to remove the infected implant and thoroughly clean the joint.
Other reasons for revision include:
- Instability of the knee replacement, often stemming from issues such as stretched ligaments or improper positioning of the implant components. This can manifest as pain or a sensation of the knee “giving way,” affecting overall function.
- Periprosthetic fractures, broken bones occurring around the implant, can also necessitate revision, particularly if the implant itself becomes loose. These fractures are often the result of falls or trauma.
- Wear of the polyethylene component, even without complete loosening, can lead to revision surgery as the plastic spacer deteriorates over time.
- Persistent pain without a clear mechanical cause can sometimes lead to consideration of revision surgery.
Understanding Knee Revision Surgery
Knee revision surgery is more intricate and time-consuming than the initial knee replacement procedure. The surgeon makes an incision, often longer than the original, to access the joint and remove the existing prosthesis, which may have integrated with the surrounding bone. If there has been significant bone loss, the surgeon may use specialized implants with longer, thicker stems that extend deeper into the bone, and bone grafting may be necessary to rebuild bone loss.
The goals of revision surgery include relieving pain, enhancing stability, and improving the overall function of the knee. It often involves removing old cement, preparing the bone surfaces, and then implanting new components. The complexity of the procedure can vary depending on the extent of damage and bone loss, sometimes requiring specialized tools and advanced surgical techniques.
Extending the Life of Your Knee Replacement
While knee replacements are designed for longevity, certain actions can help extend their lifespan and reduce the need for revision surgery. Maintaining a healthy body weight is important, as excessive weight places increased stress on the artificial joint, contributing to wear and loosening over time. Adhering to post-operative rehabilitation guidelines, including physical therapy and exercises, is also important for regaining strength and range of motion.
Patients are advised to avoid high-impact activities, such as running or jumping, which can accelerate implant wear. Regular follow-up appointments with the orthopedic surgeon are recommended to monitor the implant and address issues early. Promptly addressing any underlying medical conditions can also contribute to the long-term success of the knee replacement.