Total knee replacement (TKR) is one of the most successful orthopedic procedures of the 20th century. This is due to the substantial pain relief and restoration of function after TKR. Improvements in surgical materials and techniques have greatly increased its effectiveness. With newer implant designs and improved surgical techniques, total knee replacements can be expected to function well for at least 15 to 20 years in more than 90% of patients. However, some procedures will fail and require a second surgery, called revision knee replacement.
Revision TKR is the replacement of the previous failed total knee implants with new implants. It is a complex procedure that requires extensive preoperative planning, specialized implants and tools, prolonged operating times, and mastery of difficult surgical techniques to achieve a good result.
Peri-prosthetic Joint Infection: In total knee replacement, the large foreign metal and plastic implants can serve as a surface for the bacteria to latch onto, inaccessible to antibiotics.
Decision for Revision surgery in infection depends upon the degree of infection, duration of infection, damage to the bone and soft tissue and whether the implants are loose or not. It may vary from performing a simple washout of the knee with component retention or two stage revision surgeries: first surgery to remove the old implants and insert an antibiotic cement spacer and a second surgery to remove the spacer and insert new implants. IV antibiotics are given during this period to eradicate the infection.
Polyethylene Wear and Implant Loosening: Although implants are firmly fixed at the initial knee replacement surgery, they may become loose over time. Similarly plastic liner (polyethylene) may also wear out over the years necessitating Revision surgery.
Peri-prosthetic Fractures: The type and extent of the fracture will determine if revision surgery is needed. Peri-prosthetic fractures (fractures around the knee implants) that disrupt the fixation or the stability of the implant may require revision surgery.
Instability: Instability may be the result of injury or increased soft-tissue laxity or improper positioning or alignment of the prosthesis.
Other Factors: Age, activity level, surgical history, and weight can also contribute to failure of primary TKR.
Depending upon the history and complains of patient the surgeon will ask for X-rays, laboratory tests, and other imaging modalities like bone scans, CT scans, or Magnetic Resonance Imaging (MRI) studies. Aspiration of the knee (joint fluid removed with a needle) may be required if infection is suspected.
Around 90% of patients who undergo revision surgeries can expect to have good to excellent results. Although expected outcomes include pain relief with increased stability and function, complete pain relief and restoration of function is not always possible. Up to 10-15 % of patients may still experience some pain following revision knee surgery.