Total knee prosthesis
What is a total knee prosthesis?
The replacement of the knee joint by a prosthesis is an operation by which the damaged and worn surfaces of the tibia, the femur and the patella, three elements which form the knee, are replaced by artificial parts. Below is an x-ray of the normal knee: there is a wide, clearly visible joint space.
Below, an x-ray of the osteoarthritic knee: there is no more articular space, the surfaces in contact are completely worn. This situation causes severe pain, and severely limits the ability to walk.
The operation consists first of all in removing the damaged articular surfaces. Indeed, it is the wear of these surfaces, which can no longer slide smoothly relative to each other, which causes pain and discomfort.
Then, new surfaces and polished steel are inserted at the level of the femur and the tibia, fixed by cementing in the bone. A plastic intermediate piece ensures good sliding. The articular surface of the patella can also be replaced by a small plastic part.
PREPARATION FOR THE OPERATION
Operability
Your family doctor, or any other doctor of your choice, will be asked to make a report on your current state of health and your history, to be passed on to our anesthesia department. This will allow the anesthesiologists to assess the operative risk, and to make an informed choice of the most appropriate technique for your personal case.
Autotransfusion
Before the operation, your surgeon can recommend an autotransfusion: over a period of about 6 weeks, you will give 2 to 3 times of your blood, which will be kept for you to retransfuse just after the operation. One of our physicians in charge of autotransfusion will first give you a general medical examination, to ensure that you are fit to undergo several repeated blood samples within the indicated period of time.
Medications
In order to reduce bleeding during the operation, certain medications, in particular anti-inflammatories, must be stopped some time before the intervention: Aspirin, Voltaren, Ponstan, Olfen, Brufen, Tilur, must be stopped 10 days before the intervention , Celebrex can be taken up to 48 hours before.
Physiotherapy
A few physiotherapy sessions may be prescribed just before the operation, in order to better prepare your muscles and familiarize you with the use of canes and the correct movements. This contact with the same physiotherapists who will follow you during your stay in the clinic will facilitate postoperative rehabilitation.
Entry into the clinic and preparation
You will enter the clinic the day before the procedure, usually in the afternoon. The anesthesiologist will visit you and together you will decide on the appropriate anesthetic technique. A light sedative may be administered to you for the night before the operation, as well as just before it, but only if necessary and with your agreement.
Anesthesia
The procedure can be performed under general or loco-regional anesthesia (epidural, spinal, etc.). The advantages and disadvantages of the various techniques will be discussed with the anesthetist during the preoperative visit.
DURING THE OPERATION
The operation takes place while lying on your back, the incision is made on the front of the knee, it measures between 20 and 30 cm. The procedure itself takes approximately 2 hours.
AFTER THE OPERATION
You will spend a few hours, possibly overnight, in the recovery room or intensive care unit for postoperative monitoring. The operated knee will be covered with a bandage from which will come out drains, small flexible pipes allowing to evacuate the surplus of bleeding and thus to avoid the formation of a hematoma. These drains will be removed in the room after two to three days. In some cases, a urinary catheter is needed for some time. The first sunrise occurs the same day or the day after the operation.
To better control post-operative pain, anesthesiologists often suggest leaving a form of local anesthesia in place for a few days: a small catheter is placed in the thigh, and, using an automated pump, local anesthetic is continuously distributed to the femoral nerve: the pain coming from the front of the knee is thus softened or suppressed. Potent drugs are also administered. Pain due to osteoarthritis of the knee itself disappears quite quickly.
Rehabilitation at the clinic
After the intervention, it is a question of recovering as quickly as possible the flexion ("bend" the knee), and the extension ("extend" the knee). This rehabilitation already begins the day after the operation: the physiotherapist puts your knee on a splint which flexes and stretches the knee very slowly and continuously. The amplitude of the movement is controlled by the physiotherapist, and regulated according to the pains. There are also simple muscle strengthening exercises. After a week to 10 days, flexion should reach 70 to 90 degrees, and extension should be complete.
Institutional rehabilitation
For elderly patients, it is sometimes appropriate to continue rehabilitation in a specialized hospital environment, that is to say in a CTR (Treatment and Rehabilitation Center), where physiotherapists continue the work started at the clinic. Various centers in the region are available: Sylvana, the hospitals of Lavaux, Aubonne and Orbe, the Valmont clinic in Glion and La Lignière on La Côte.
Home rehabilitation
For younger patients in good physical shape, it is possible to go directly home. It will then be necessary to follow an outpatient treatment with a nearby physiotherapist (some can even come to your home the first few times), at the rate of 2 to 3 sessions per week.
In order to reduce the risk of postoperative thrombosis (blood clot obstructing a vein in the leg), you will receive anticoagulant treatment (which keeps the blood in a thinner state than usual) in the form of tablets or injections for several weeks. after the operation. White bands (TED), going up to below the knee, are put on every getting up until the end of the stay in the clinic; they also serve to reduce the risk of thrombosis.
POSTOPERATIVE FOLLOW-UP
With some exceptions, I close all the scars with intradermal stitches, that is to say which do not appear on the skin: there are therefore no "small holes" on either side of the incision. There are also no wires or staples to remove. The skin is closed with small tapes called steristrips, which you can remove yourself 2 weeks after the operation.
The evolution of the operated knee is monitored by regular check-ups at the consultation, accompanied by X-rays, generally according to the following scheme: 6 weeks, 3 months, 1 year, 5 years and 10 years after the operation.
The canes can be gradually abandoned between 3 and 6 weeks after the operation.
In the longer term, care must be taken to prevent secondary infection of the prosthesis. This can happen any time bacteria are released into the bloodstream, such as during a dental procedure, examination, or surgery on the bladder or bowel. Always tell any doctor treating you that you have a knee prosthesis.
In airports, passing through certain metal detectors can trigger the alarm. A certificate in French and English will be given to you, attesting that you have a prosthesis.
After 3 to 6 months, the patient can resume an almost normal life. Some sports such as cycling, swimming, walking or skiing can be practiced.
© Dr. P. Zangger, Lausanne.