What are the risks of revision knee replacement surgery? +
The risk of complications is generally higher in revision surgeries compared to primary knee replacements.
General complications of knee replacement surgery can include:
Infection
The risk is less than 1 in 100 of developing an infection. This is higher than the 1 in 400 risk in primary knee replacement surgery. This can occur despite using a sterile surgical technique and giving pre-operative intravenous antibiotics.
If the infection involves only the wound (superficial), it may just need treatment with a course of antibiotics.
If a deep knee joint infection occurs, it may require more surgery to wash out the knee as well as intravenous antibiotics. During the final washout, the plastic liner within the knee may be removed and replaced with a new sterile liner in order to decrease the bacterial load.
If this fails to control the deep infection, the knee replacement may require removal, and an antibiotic impregnated cement spacer may be inserted. After an appropriate period of intravenous antibiotics, if the deep infection is cured, the cement spacer may be removed and a new knee replacement reimplanted.
Bleeding
Bleeding can occur around the incision or into the knee joint itself. This is usually self-limiting, but on rare occasions will require re-operation to wash out the accumulated blood.
Deep vein thrombosis
Clots can occur in the deep veins of the leg that may dislodge and occlude the arteries in the lungs. DVT presents as leg pain and swelling after your operation. The diagnosis is confirmed with an ultrasound scan and, depending on the type of DVT, may require treatment with blood thinners.
Specific complications of knee replacement surgery can include:
Ongoing pain
Despite the knee replacement being performed well, 1 in 10 people are dissatisfied with the end result. This is in the absence of any problem in the knee such as infection, loosening, or incorrect alignment of the knee replacement.
Stiffness
The knee can become stiff after surgery due to the formation of scar tissue. This stiffness usually resolves with physiotherapy but can sometimes persist. If the knee is not bending or straightening adequately 6-8 weeks post-operatively, a manipulation procedure may be required. This involves putting the patient to sleep and pushing on the knee to break the scar tissue.
Loosening
Loose microscopic particles from the plastic liner of the knee replacement can induce a bodily response that causes the loss of bone around the prosthesis (osteolysis). With time, this can cause the prosthesis to loosen and cause knee pain with activity. Although the components are designed to survive 20 years or more in most cases, loosening can sometimes occur early. Symptomatic loosening necessitates a revision procedure.
Instability
Whilst performing a knee replacement, attention is given to making sure the fit is tight enough to give the knee stability. but loose enough to allow motion. It’s rare, but sometimes damage to the surrounding ligaments or incorrect sizing or placement of the prosthetic components can result in the knee feeling unstable. If this occurs, it may require a revision procedure to address the instability.
Polyethylene wear
If the plastic implant becomes worn over time, the components loosen, or there are issues with stability or positioning of the prosthesis, it may require a revision procedure.
Intraoperative fracture
Although not a common occurrence, it's important to note that the risk of fracture during revision knee replacement surgery may be higher for patients with osteoporosis. Specifically, this risk may arise during the removal of the existing prosthesis or implantation of the new revision prosthesis. Significant fractures require surgical fixation with metal screws and potentially a metal plate. A stem may need to be added to the prosthesis in order to bypass the load through the fracture site.
Why do knee replacements fail? +
Knee replacement surgery for osteoarthritis is known to yield favorable outcomes, with patients experiencing a significant improvement in their mobility and quality of life, often free from pain or stiffness. Nevertheless, there may be instances when revision surgery becomes necessary. Here are some reasons why a knee replacement may require such a procedure.
1. Infection
Infection is a significant cause of revision knee replacement surgery. Infections can occur during the initial surgery or develop afterward due to various reasons, such as poor wound healing or systemic infections. An infected knee prosthesis may cause pain, swelling, redness, and fever. Infection can erode the bone around the knee replacement prosthesis and cause it to loosen.
Infections in knee replacement surgeries can be caused by a variety of organisms. The most common organisms responsible for these infections include:
Staphylococcus aureus: A bacterium commonly found on the skin and in the nose, Staphylococcus aureus is a frequent cause of surgical site infections, including those involving knee replacements. Methicillin-resistant Staphylococcus aureus (MRSA) is a particularly concerning strain due to its resistance to many antibiotics.
Coagulase-negative staphylococci (CNS): These bacteria, such as Staphylococcus epidermidis, are part of the normal skin flora and are less virulent than Staphylococcus aureus. However, they can still cause infections in knee replacements, particularly in patients with weakened immune systems or other risk factors.
Infection can be a serious and distressing complication that may arise following knee replacement surgery, and effective treatment often requires a comprehensive approach involving a range of medical professionals. This can include collaboration between orthopedic and plastic surgeons, infectious disease specialists, and nutritionists, each contributing their unique expertise to provide the best possible care for the patient.
2. Loosening or Wear of the Prosthesis
Over time, the artificial joint may wear out or loosen from the bone, leading to loosening or wear of the prosthesis. This can cause pain, reduced function, and instability in the knee. Loosening can result from natural wear and tear, mechanical failure, or bone loss around the implant. When the prosthesis becomes unstable, a revision surgery may be required to replace the worn or loose components.
3. Instability or Dislocation
Instability or dislocation of the knee joint can also necessitate revision surgery. This can occur if the ligaments around the knee joint are inadequate or if the prosthesis was improperly aligned during the initial surgery. Instability may result in pain, difficulty walking, or even dislocation of the knee joint. Revision surgery can address these issues by correcting the alignment and providing proper support to the knee.
4. Stiffness or Limited Range of Motion
In some cases, patients may experience stiffness or limited range of motion after their initial knee replacement surgery. This can be due to scar tissue formation, improper positioning of the prosthesis, or other factors affecting the knee's mobility. A revision surgery may be necessary to address these issues and restore the knee's proper function.
5. Periprosthetic Fracture
A periprosthetic fracture is a break in the bone around the knee prosthesis. This can occur due to a fall, trauma, or weakening of the bone surrounding the implant. These fractures can cause pain, instability, and difficulty walking. In some cases, a revision surgery may be needed to fix the fracture and stabilize the knee joint.
6. Component Malposition or Misalignment
If the components of the knee prosthesis are not positioned or aligned correctly during the initial surgery, it can lead to component malposition or misalignment. This can cause pain, instability, and premature wear of the implant. Revision surgery can help correct the positioning and alignment of the prosthesis, providing better knee function and longevity.
What is a two-stage revision knee replacement? +
In severe cases, a two-stage revision is the preferred approach for managing infected knee replacements, as it provides the best chance for eradicating the infection and ensuring a successful outcome. The two-stage revision process involves the following steps:
Stage 1: Removal of the Infected Prosthesis and Infection Control
Surgical removal of the infected prosthesis: The surgeon will remove the infected knee prosthesis along with any surrounding infected or damaged tissue.
Debridement and irrigation: The surgical site is thoroughly cleaned and debrided, removing any remaining infected tissue and debris. The area is irrigated with an antiseptic solution to help eliminate the infection.
Antibiotic spacer placement: A temporary antibiotic-impregnated spacer is placed in the knee joint to maintain proper alignment and spacing during the interval between the two stages. The spacer also delivers high concentrations of antibiotics locally, further aiding in infection control.
Systemic antibiotics: After the first stage, the patient is typically prescribed intravenous (IV) or oral antibiotics for a specific duration (usually 6-8 weeks) to help clear the infection. The choice of antibiotics is guided by the results of bacterial cultures obtained during surgery and the organism's susceptibility to various antibiotics.
Stage 2: Implantation of the New Prosthesis
Evaluation of infection clearance: Before proceeding to the second stage, the surgeon will assess the patient for signs of infection clearance. This may involve blood tests, imaging studies, or joint aspiration to ensure the infection has been successfully treated.
Surgical implantation of the new prosthesis: Once the infection has been eradicated, the surgeon proceeds with the second stage of the revision. The temporary antibiotic spacer is removed, and a new knee prosthesis is implanted, ensuring proper alignment and stability.
What is the outcome following revision knee replacement surgery? +
Success rates for revision knee replacement surgery vary depending on the reason for the revision, the patient's overall health, and other factors. Generally, revision surgeries have lower success rates than primary knee replacements. However, most patients experience significant improvements in pain and function following revision surgery.
