Total Knee Replacement
What is a total knee replacement ?
By "replacing the knee" one means surgically substituting the damaged joint surfaces of the arthritic knee using especially designed metal and plastic parts.
Below, radiograph of a normal knee: there is a broad joint space.
The next radiograph shows an arthritic knee: there is no joint space left, and the articular surfaces are worn down to the bone. In this situation, the knee is wery painful, and the ability to walk is greatly reduced.
The surgery starts by removing the damaged joint surfaces.
Then new surfaces made of polished stainless steel are inserted on both the femoral (thighbone) side and the tibial (shinbone) side. Fixation is achieved by cemented or cementless techniques.
A middle part made of polyethylene (a particular kind of plastic) is inserted between the metal parts, ensuring a smooth gliding motion of the new joint.
The joint surface of the patella (kneecap) may be replaced by a plastic "button".
Preparation to the surgery
Before surgery, you need to go to your family doctor for a check-up. It will help our anesthetists to choose the anesthetic technique that is most appropriate for you.
In order to diminish blood loss during surgery, non-steroidal anti-inflammatory drugs such as Aspirine, Voltaren, Ponstan, Olfen, Brufen, Tilur must be discontinued 10 days before surgery.
Some physiotherapy may be prescribed preoperatively, in order to improve muscle strength and to get acustomed to the use of crutches.
For total knee replacement, patients usually are hospitalised the day before surgery around 4 PM. The anaesthetist will examine you and discuss different options, and together you will choose the method of anesthesia that is best suitable for you. The surgery can be performed under general or epidural anesthetic.
I perform this surgery with the patient lying on his/her back. The incision is anterior (in the front of the knee)and is about 20 cm long. The procedure lasts about 2 hours.
You will stay in recovery room for about 2 hours, after which you will be brought back to your room. The day after surgery will be spent resting in bed for transfusion and pain control. 1 or 2 suction drains will be kept until day 3 to avoid hematoma formation. in some cases, a urinary cathether is inserted during the anesthesia, and removed after 2 to 3 days.
On day 3, a physical therapist will get you up and start walking exercises with full weight-bearing on two crutches. These are to be used for about 3 to 6 weeks, and be discontinued progressiveley as you make progress and gain self-confidence.
Postoperative pain may be lessen by the use of continuous epidural analgesia (a catheter is left in your spine and delivers pain medicine to the nerves of your legs continuously for 2 to 3 days). The anaesthetist may also elect to insert a femoral catheter at the groin, to lessen the pain in the anterior aspect of the knee.
On day 2, the leg is installed on a kinetec machine, which will help you bend and stretch the operated knee very gently and very slowly. The flexion angle will be increased slightly every day.
Deep vein thrombosis (DVT) (obstruction of a vein of the leg by a blood clot): in order to lower the risk of DVT, a blood-thinning medication must be taken for 4 weeks after surgery (one subcutaneous injection per day)
Infection: even long after your surgery, the prosthetic joint can become infected, particularly if you have a severe infection (pneumonia, or septicaemia for example). During the first year after implantation, it is recommended that you take oral antibiotics before and after dental surgery or dental cleaning, coloscopy, gastroscopy, cystoscopy or sinuscopy.
Follow-up visits of your new knee are performed 4 weeks and 3 months after surgery, then every year.
Some prosthetic parts may trigger alarms from metal detectors at airports or at building doors. A certificate will be issued to you, attesting that you bear a metallic implant in your hip.
After 3 to 6 months, almost all aspects fo everyday life have usually been resumed. Some sports are to be avoided: all ball sports, long-distance running, tennis, squash.
© Dr. P. Zangger, Lausanne.