Revision Knee FAQs
What are the reasons for undergoing revision knee replacement surgery?
Revision knee replacement surgery may be done for loosening of the knee implant, for infection in the artificial knee joint, for a fracture surrounding the artificial knee joint that has led to loosening of the knee joint, or for a patella that is dislocating.
What causes the kneecap to dislocate after primary knee replacement surgery?
The most common reason for kneecap to dislocate after primary knee replacement surgery is because the femoral implant is not aligned correctly in the right rotation on the thigh bone. To clarify, if the femoral implant is rotated internally during the surgery, then the kneecap dislocates to the outside because of the forces pulling the kneecap to the outside of the knee joint. The way to resolve it is, unfortunately, revision knee surgery in which the femoral component has to be removed and replaced correctly in correct rotation.
When the surgery is done, in addition to rotating the component and placing it in the correct position, the stem typically has to be placed into the thigh bone to provide additional stability. Depending upon the implant that was used for the primary knee replacement surgery, the tibial component (component going into the shin) also may need to be revised, because the revision knee replacement femoral component will not articulate with the distal component that is placed into the shin bone.
In my experience, most knee revisions typically need replacement of all three components of the knee joint, the femoral component, the tibial component, as well as the plastic that is between the femoral and the tibial component. It is rarely needed to replace the component under the kneecap even when the kneecap is dislocating. Under the circumstance where the kneecap dislocates in the postoperative period after a primary knee replacement surgery, its important to check if the kneecap was dislocating before the knee replacement surgery and there was arthritis associated with subluxation or dislocation of the kneecap.
Under those circumstances, there are two options available: To do a femoral osteotomy to rotate the femur along with doing a knee replacement surgery, which I feel is extensive procedure. The other option, which is a much lesser procedure, is realigning the tibial tubercle when the revision knee replacement surgery is performed. I get a CT scan If I see any rotational malalignment.
How long does it take to recover from revision knee replacement surgery?
Recovery from knee replacement revision surgery is typically longer than a primary knee replacement surgery and depends on what was done during the knee replacement surgery. If only the plastic was changed, the recovery is significantly faster, sometimes faster than in the primary knee replacement surgery, because there was nothing done to the bone.
What are the circumstances in which only the plastic is revised during revision knee replacement surgery?
Revision of a plastic during a knee replacement surgery is rarely done. The reason would be if the knee is loose or has loosened after a knee replacement and the surgeon wants a thicker plastic between the knee joint to provide additional stability. Another reason would be if the primary knee was posterior cruciate ligament (PCL) sparing knee joint, meaning that one of the ligaments in the knee joint, the posterior cruciate ligament, was left behind in the knee joint and has given way. Under this circumstance, the plastic, which was PCL sparing, is removed and can be replaced with the cruciate substituting plastic.
However, in all likelihood, if the PCL sparing knee was performed, the femoral component does not accept the plastic that is there, which is cruciate substituting, and therefore the femoral as well as the tibial component, has to be revised. To summarize, the most common reason for changing only the plastic, is if the knee is loose and the reason for the loosening is the smaller size of the plastic, or if the surgeon feels that a larger “stabilizing post” with a thicker poly will cure the reason for unstable knee joint.
What are they symptoms of infection in the knee replacement?
Infection in the knee replacement can happen suddenly or over an insidious onset. Sudden infection in the artificial knee will manifest as sudden increase in pain, inability to bear weight, swelling and redness of the knee, and also may be manifested as a spike in fever because of the bacteria from the knee entering the blood system. Insidious onset in the knee replacement will manifest as slowly increasing pain, redness and swelling. The patient, especially if immunocompromised, may not have a spike in fever.
How do you diagnose an infection in an artificial knee joint in the most accurate manner?
The most accurate way to diagnose infection in an artificial knee is to aspirate the knee joint and send the fluid for cell count with differential, culture and sensitivity, and for gram stain. In addition, we also get blood tests done to look at CBC, ESR, and CRP.
How do orthopedic surgeons treat acute onset infection in the artificial knee joint?
Acute onset infection of the artificial knee joint is treated based on the time of onset of the infection after the knee replacement surgery, and if the implant is loose or not, among numerous factors. If the implant is recently placed into the patient, and if the infection occurs in the immediate postoperative period, typically irrigation and drainage, and change of the plastic is the final treatment along with IV antibiotics for about six weeks.
If the patient has had infection with loosening of the implant, then a two stage reconstruction is required, which involves taking the infected knee out, placement of antibiotic spacer treatment of the patient for about six weeks with IV antibiotics, aspirating the knee again to ensure that there is no infection, and then the revision knee replacement.
What sort of spacers do orthopedic surgeons place in the knee joint?
For treating infection in the artificial knee, there are two types of spacers that are placed into the knee joint. Surgeons prefer to use articulating spacers instead of static spacers. Articulating spacers are spacers that are shaped like the knee joint and allow a range of motion at the knee joint. Literature has shown that if static spacers are used, additional surgical exposures are needed to take the spacer out and do the revision.
These additional procedures cause the revision surgery to be more invasive. Additionally, the range of motion after the final knee revision is less if the static spacers are used as spacer blocks. There are a variety of sizes available with articulating spacers, and today it’s the implant of choice for treating infection in the artificial knee.
What do orthopedic surgeons do in the surgical procedure to treat the infected knee? What is the first stage?
The first stage is removal of the earlier implant that is infected, and placement of the antibiotic spacer. I do accurate preoperative planning. There are a variety of molds available, and I pick the size of mold even before making the skin incision. After selecting the size of the mold, I mix about one gram of tobramycin, one gram of vancomycin into the cement that is placed into the mold. The selection of antibiotics is changed if the preoperative aspiration shows the bacteria being sensitive to a different antibiotic than vancomycin and tobramycin.
After the antibiotic loaded cement is mixed into the mold, the cement is hardened and I peel the mold prior to making the incision. The incision is made in the knee joint and the components are removed, thorough irrigation and debridement is done, the antibiotic loaded spacer is placed into the knee joint, and the wound is closed. Postoperatively the patient ranges the knee to comfort, and the final range of the knee after the second surgery is better with articulating spacers compared with static spacers.
How much does it cost to get revision knee replacement surgery?
All insurances cover revision knee replacement surgery. Commercial carriers may have a deductible with their out-of-network benefits, or with their in-network benefits. The insurance verification has to be performed prior to the procedure and the patient knows the exact cost of the surgery including the patient’s deductible.
After the insurance plan has been verified with Medicare, which pays 80 percent of the allowed amount for the procedure, the supplementary or the secondary is able to pick up the remainder 20 percent. With certain supplementary plans, like AARP, there is no deductible. However, with certain secondary insurance there may be a deductible before the secondary covers the 20 percent that the Medicare does not cover.
How long does revision knee surgery last? What’s the life of revision knee implant?
The life of revision knee surgery depends on what was performed during the procedure, the quality of the bone, and the fixation of the implant. If significant invasiveness is needed to achieve fixation from revision knee replacement surgery, the muscle rehabilitation may take several months. If the bone is deteriorated, perhaps from an infection adjacent to the prosthesis, the knee replacement may not last a very long time. Unfortunately, very little literature exists looking at revision knee replacement surgery, and it is difficult to quote literature (the surgeon can quote literature with the primary knee replacement).
What causes a septic loosening that leads to revision knee replacement surgery?
A septic loosening is loosening at the interface of the implant and the bone, or it could be loosening at the interface between the cement and the bone. With time, there is wear of the plastic, and the plastic can eat into the bone causing osteolysis. If the osteolysis is significant, implant fixation is compromised. There are certain uncemented implants which have poor track record, and those implants loosen out earlier than cemented knee replacement surgeries that have had a longer track record.
There are also certain designs of knee replacement surgery, which allow more percolation of the debrided plastic into the bone, and there’s a thought that there is more osteolysis associated with certain designs of knee implant. It is therefore necessary to get annual radiographs and a physical examination to see if there is significant osteolysis (bone erosion), after a knee replacement.
Can I kneel after revision knee replacement surgery?
Depending on what was performed during the revision knee replacement surgery, patients may or may not be able to kneel after the surgery. Patients are most certainly not able to kneel with the first stage of infection knee procedure, in which antibiotic spacer is placed into the knee joint. After the second procedure of the infected knee joint, when the antibiotic spacer is removed and the final revision surgery is performed, it is likely that the patient will be able to kneel.
Even after a primary knee replacement surgery, it is unpredictable if patients can kneel after the surgery, but unfortunately it is even more unpredictable after revision knee replacement surgery. We realize that for certain patients, kneeling is an important activity, for example kneeling in church. However, activity modification is advised to the patient prior to having knee replacement surgery.
Can I get bursitis after revision knee replacement surgery?
Bursitis is possible after a knee replacement surgery, however it is rare. If there is inflammation around the artificial knee implant, it is critically important to rule out an infection. I start with a thorough physical examination, radiological examination. If the knee is intact, and MRI is obtained to show the soft tissues around the knee joint, and bursitis in the soft tissues will be better observed with an MRI.
However, after a knee replacement surgery some better imaging sequences have to be performed for better evaluation of the soft tissues because there may be significant scatter of the CT scan or the MRI that may interfere with visualization of soft tissue after knee replacement surgery.
Have knee implants been recalled?
Unfortunately, there have been recalls of knee implants. Implants that have worked very well in labs did not perform in patients. I have used implants which have had a track record of at least a few years, and for this reason have been able to have good long-term clinical results after knee replacement surgery.
Will I need blood after knee revision surgery?
Knee revision surgery is performed under a tourniquet, which means that the limb is exsanguinated and the tourniquet is placed over the thigh and is tightened till the end of the procedure. Most of the surgery is performed in a bloodless manner, however certain types of knee revision surgeries require that the procedure be done over several hours. In these type of surgeries, the tourniquet has to be let down, and although hemostasis is achieved, there may be blood loss intraoperatively which may need a blood transfusion.
For patients who undergo a spacer, the spacer is not strongly adherent to the bone because it’s an antibiotic spacer, and the idea is not to cement it to the bone because removing the spacer in the second stage will lead to more bone loss. Therefore, in patients who get a spacer, there is blood loss, not during the surgery but during the postoperative period. Patients who get a spacer after the removal of the knee joint do a transfusion on the second or the third day.
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