INTRODUCTION
A revision knee replacement surgery is a procedure that is performed to replace a knee implant that is no longer functioning properly. Most knee replacements last several decades, some longer. However, there are also times when a knee replacement needs to be redone after years or even just months. Understanding why a knee replacement has worn out is critical to performing a successful revision knee replacement.
The average knee replacement lasts more than two decades, and there are reports of implants lasting longer, and new materials and surgical techniques are hoped to provide even longer-lasting knee replacements. That said, there are times when knee replacements may last a very short time, even in otherwise healthy patients. A small percentage of patients (around 1-2%) end up requiring a knee replacement revised within a few years of their initial surgery.
Revision replacements are performed for a number of reasons. Some of the more common include:
Loosening of the implant
Infection of the joint
Instability of the knee
Malalignment of the components
Many people ultimately have a revision knee replacement because the problem is causing significant pain. While pain can be a problem in itself, a revision knee replacement surgery should not be performed without understanding why the pain is occurring. Performing this type of surgery for pain without an identified cause is unlikely to yield good results.
Instead, the cause of the problem with the knee replacement needs to be precisely understood, and there needs to be a plan to address that problem with the implant. An operation without a clear plan to address the problem is unlikely to be helpful.
Complexity in revision surgeries
Revision replacement is difficult for several reasons. First, when someone has had surgery, scar tissue develops, and soft tissues become less identifiable. Performing the second surgery is always more difficult. Second, when performing a knee replacement, bone is removed. When performing a revision knee, often more bone has to be removed, and some may be lost as a result of the problem with the implant. Maintaining adequate bone to support the new implant can be a challenge. Finally, obtaining a knee that is flexible enough to allow for motion, yet stable enough to keep you steady, is also more difficult in revision situations.
PRE-OPERATIVE PHASE
Your surgeon will send you for routine blood tests to rule out infection, CT scan to look closer at the anatomy, and bone scans to help to determine if a component is loose.
X-rays and/or MRI will be considered.
Aspiration of the knee joint is occasionally done to diagnose or rule out infection
Patient will be asked to undertake a general medical check-up with a physician
Patient should have any other medical, surgical or dental problems attended to prior to the surgery in order to prevent a risk of infection.
Cease aspirin or anti-inflammatory medications 10 days prior to surgery as they can cause bleeding.
Any antiplatelet drugs / blood thinners such as clopidogrel, warfarin will be stopped 3-7 days prior to the date of surgery.
Surgical consent will be explained to the patient detailing the procedure as well as the risks involved, if any.
Blood transfusion, if required will be informed and done.
Day of surgery
You will meet the nurses and answer some questions for the hospital records
You will meet your anesthetist, who will ask you a few questions and assess the risk factors for surgery.
You will be given hospital clothes to change into and have a shower prior to surgery
The operation site will be shaved and cleaned
Approximately 45 minutes prior to surgery, you will be transferred to the operating room
After explanation of the procedure, you will be asked to sign the consent for surgery. Occasionally, a high risk consent for surgery may be requested depending on the blood reports and clinical examination.
SURGICAL PROCEDURE
Each knee is individual and knee replacements take this into account by having different sizes for your knee. If there is more than the usual amount of bone loss, sometimes extra pieces of metal or bone are added.
Surgery is performed under sterile conditions in the operating room under spinal or general anesthesia. You will be on your back and a tourniquet will be applied to your upper thigh to reduce blood loss. Surgery takes approximately two hours.
The patient is positioned on the operating table and the leg prepped and draped.
A tourniquet is applied to the upper thigh and the leg is prepared for the surgery with a sterilizing solution.
An incision around 7cm is made to expose the knee joint.
Old/ damaged components of the implants are removed.
The bone ends of the femur and tibia are prepared using a saw or a burr to freshen the bone.
Trial components are then inserted to make sure they fit properly.
The real components (Femoral & Tibial) are then put into place with or without cement.
The knee is then carefully closed and drains usually inserted, and the knee dressed and bandaged.
POST- OPERATIVE MANAGEMENT
When you wake up you will be in the recovery room with intravenous drips in your arm, a tube (catheter) in your bladder may be inserted, and a number of other monitors to check your vitals.
Once stable, you will be taken to the ward.
The postop protocol is surgeon dependent, but in general your drain will come out at 24 hours and you will sit out of bed and start moving your knee and walking on it within a day or two of surgery. The dressing will be reduced usually on the second postop day to make movement easier. Your rehabilitation and mobilization will be supervised by a physical therapist.
To avoid lung congestion, it is important to breathe deeply and cough up any phlegm you may have.
Your surgeon will use one or more measures to minimize blood clots in your legs, such as inflatable leg coverings, stockings, and injections to thin the blood clots or DVT’s.
A lot of the long-term results of knee replacements depend on how much work you put into it following your operation.
Usually you will be in hospital for 3-5 days and then either go home or to a rehabilitation facility depending on your needs. You will need physical therapy on your knee following surgery.
You will be discharged on a walker or crutches and usually progress to a cane at six weeks.
Your sutures will be removed at approximately 12-15 days.
Bending your knee is variable, but by 6 weeks it should bend to 90 degrees. The goal is to get 110-115 degrees of movement.
Once the wound is healed, you may shower. You can drive at about 6 weeks, once you have regained control of your leg. You should be walking reasonably comfortably by 6 weeks.
More physical activities, such as sports may take 3 months to be able to do comfortably.
You will usually have a 6-week checkup with your surgeon who will assess your progress. You should continue to see your surgeon for the rest of your life to check your knee and take X-rays. This is important as sometimes your knee can feel excellent but there can be a problem only recognized on X-ray.
You are always at risk of infections especially with any dental work or other surgical procedures where germs (bacteria) can get into the blood stream and find their way to your knee.
If you ever have any unexplained pain, swelling, redness or if you feel unwell you should see your doctor as soon as possible.
A Revision Knee replacement is a complex procedure and requires a highly skilled surgeon with adequate expertise. Our Consultant in chief, Dr Vikas Jain is one of the few surgeons in the region who is trained from Europe and has adequate surgical experience in such complex revision procedures.
