Knee prosthesis revision is a prosthesis replacement surgery performed in those who have had knee replacement surgery before. In this operation, known as “re-operation”, the prosthesis in the patient is removed and a new prosthesis is placed.
In some cases, it may be necessary and sufficient to replace a part of the prosthesis in the joint, while sometimes it may be necessary to completely replace all the prosthesis parts. It is an operation that requires a detailed pre-operative planning, special prosthesis sets and materials, and requires a longer operation and recovery time than the first prosthesis.
Who needs knee replacement revision surgery?
Ninety percent of patients who have had a total knee replacement surgery use the prosthesis for about 20 years without any problems. When the functions of the knee joint deteriorate due to wear and tear, loosening and inflammation; difficulty walking and pain in the knee begins. In knee prosthesis performed at advanced ages, patients can use the prosthesis for a lifetime without any problems.
At a young age, and especially in those who lead an active lifestyle, over time, the knee prosthesis may wear out and its function may deteriorate. However, the life of the prosthesis can be extended even more in young and active people with applications such as newly developed high-end technological prostheses and kinematic surgical techniques including robot-guided knee prosthesis surgery.
What are the most common reasons for knee replacement revision surgery?
Infection: It is a potential complication that can be seen after knee replacement surgery just like in any other surgery. It can occur while you are in the hospital, after you go home, and even years later. The risk of infection after knee replacement surgery is less than 1%. If infection develops, then there is loosening of the prosthesis. In these patients, complaints such as pain, swelling, redness, increased local temperature and sometimes discharge occur in the knee.
When the infection is detected early on; The treatment is easier and follows washing, surgical cleaning (debridement), sparing the metal parts in place and replacing the plastic spacer is sufficient. However, in late-onset or late-detected infections, 2-stage revision surgery is required. In the first stage, the prosthesis is removed, the inside of the joint is cleaned and washed, and a cement filler with antibiotic is added. After a few months of antibiotic treatment, when it is determined that the infection has been eradicated, the second stage is initiated and a new knee replacement surgery is performed.
Space and imbalance in the knee: After the wear and tear of the knee prosthesis over time, the function of the ligaments that support and balance the knee joint may deteriorate. While standing, moving the knee or walking, the knee functions are impaired because the ligament support that is required is impaired. In this case, revision surgery is performed to replace the worn prosthetic part or the affected parts of the knee.
Stiffness: Sometimes after knee replacement surgery, the range of motion required to perform daily activities may be lost or limited. It may be caused by excessive scar tissue formation around the joint during the healing process. In the early period, "manipulation under anesthesia" is performed in order to stretch the joint and increase the range of motion.
In this procedure, you will be given anesthesia so that you do not feel pain. The doctor bends your knee to relieve the adhesions. In most cases, this procedure is successful in improving range of motion. But sometimes the knee remains stiff. Revision surgery may be required if extensive scar tissue or the location of components in your knee are limiting your range of motion.
Abrasion and loosening: Due to the friction between components, wear and tear, loosening and fracture may occur in the parts of prosthesis. For a knee prosthesis to be functional, the prosthesis must be firmly attached to the bone. Cement is mostly used for this. However, if the bone attachment of the prosthesis weakens over time, the prosthesis may loosen and the knee may become painful.
The reasons for loosening are not always clear. Activities that force the knee joint, knee prosthesis performed in those who are active at early ages, excessive weight bearing and wear of the plastic spacers between the two metal components of the prosthesis are the factors that can cause it.
Small particles that arise due to the wear of the plastic spacer called the insert, accumulate in the joint and the body's immune system develops a reaction against them. This unwanted reaction causes destruction of the healthy bone around the prosthesis, this is called osteolysis. With the resulting osteolysis, destruction occurs in the bone supporting the prosthesis and the adhesion of the prosthetic bone weakens and the prosthesis becomes loose. After relaxation, the balance of the knee is disturbed and causes pain. In such a case, knee prosthesis revision surgery should be performed.
Fractures around the prosthesis; These fractures involve the bone around the components of the knee replacement. These fractures are most often the result of a fall and usually require knee replacement surgery. In order to decide what to do in revision surgery, it is necessary to evaluate factors such as the quality of the bone, the type and location of the fracture, and whether the prosthesis is loose.
Examinations performed before knee prosthesis revision surgery
Some laboratory tests and radiological imaging studies are employed to learn more about the condition of the knee.
X-ray; It is the first examination requested to evaluate the condition of the prosthesis and bone structure. Bone scintigraphy, which is one of the other imaging examinations, is helpful in determining the presence of loosening of the prosthesis, this imaging method is used if the findings cannot be clearly confirmed with an x-ray. At the same time, bone scintigraphy gives information about whether the loosening is due to infection or wear and tear. Computed tomography (CT) is another imaging method used to better reveal the bone structure and for 3-dimensional visualisation.
Laboratory tests; blood tests are ordered to determine if an infection is present. In addition, in cases where there is loosening in the knee prosthesis, it may be necessary to examine a fluid sample taken from the joint to distinguish the infection. Various laboratory analyses are performed to determine whether there is an infection in the fluid taken from the joint using a syringe.
How is knee revision surgery performed?
Knee prosthesis revision surgery is more complex and takes longer than the first knee prosthesis surgery. While the first knee prosthesis surgeries take around 40 minutes, prosthetic revision surgeries may take 1-2 hours. In knee replacement revision surgery; The access to the joint is achieved from the older scar. It is reassessed for infection. All metal and plastic parts of the prosthesis are evaluated to determine which parts of the prosthesis are worn, loose or dislodged. The prosthetic pieces are carefully removed to protect the bone. If cemented prosthesis has been used before, cement residues are cleaned. After this stage, bone surfaces are prepared for revision prosthesis.
In some cases, significant bone loss may have occurred. If this is the case, metal reinforcements and platform blocks can be added to the main components of the prosthesis to compensate. After these procedures, the cemented knee revision implant is fixed to the bone. Afterwards, the joint capsule is repaired and a catheter is placed to drain the blood and fluid from the joint.
Risks and complications of knee replacement revision
As with any surgery, there are some risks in knee replacement surgery. Because it is longer and more complex than the first knee replacement, the risk of complications is also higher. Possible risks and complications in knee prosthesis revision surgery; Wound opening, infection, bleeding, limitation of movement and stiffness, bone fracture, nerve or vessel damage, clot formation in the vessel, pulmonary embolism.
After knee prosthesis revision surgery, the majority of patients regain their functions with a painless and stable knee joint. However, it may not always be possible for the pain to completely disappear and the knee joint to reach its former mobility.