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Total knee replacement


What is the total knee replacement?

During the total knee replacement surgery, the surfaces of the bony areas that rub with each other are remodeled and replaced by metallic and plastic implants. By usage of high precision special instruments, the surgeon eliminates the damaged surfaces of the three bones. Then he fixes the implants in their respective positions.
The superior bone surface is replaced by a metallic, round-shaped component which is very similar to the curvature of the natural bone. The surface of the inferior bone is replaced by a flat metallic component that contains a heavy molecular weight, polyethylene plastic block, which serves as a cartilage. The inferior surface of the rotula can be replaced by a round plastic disc of the same polyethylene.



How can I find out if I need a total knee replacement?

Your orthopaedic surgeon will have you undergo a detailed knee examination, which will include a movement width test, to check how far you can extend and flex your knee. Also he will evaluate whether you have any deformities in your legs that could manifest themselves in the shape of affections, like bow-shaped or scissor-shaped legs. You will be required to walk, sit, and probably climb up and down some stairs.
Your surgeon will ask you several questions to determine your clinic history, inquire on your injuries, infections and any other disorders you may have had in the past.
He will need to know exactly which medicines you are taking, and, of course, he will ask you to describe your knee pains.
Lastly, the surgeon will run some x-rays that he will later on use to perform more evaluations regarding your knee joint status. Should you decide to go ahead with a total knee replacement surgery; these x-rays will be of much assistance for the surgeon when selecting the best artificial knee type and size for you.
According to the results of these exams, the surgeon will determine if you are a candidate for a total knee replacement. Although it is practiced quite often, the total knee replacement is a major surgical intervention that should only be considered when any other alternative treatment is discarded.
There are several much more conservative treatments that you and your surgeon should evaluate, for example, oral medication or pain injections, physiotherapy and other kinds of surgery.
The last word on whether you should go through this operation is yours, so it is really important that you understand the risks that this surgery entails. There are complications that may manifest themselves during or after surgery, amongst these there are; blood clots, infections, pneumonia, prosthesis loosening and nerve damage. Your surgeon will answer every specific question you have about these risks.



What does a total knee replacement surgery imply?

Before surgery:

If both you and your surgeon decide it is best for you to undergo a total knee replacement, a date will be set for your operation. It could be necessary to make several preparations beforehand For example; your surgeon may ask you to check with an internist or your head doctor. Since it is most likely you will need blood transfusions during surgery, you may be interested in donating one or two blood units - if your surgeon deems necessary -. You will be able to donate one unit per week before the surgery.


During surgery:

The date of the surgery, you will have an intravenous probe placed in your arm, to supply all the medications and liquids that are necessary during the operation. You will then be taken to the operating room where they will anesthetize you. Once the anesthesia takes effect, your knee will be rubbed with a special solution to sterilize it. Starting the surgery, an incision will be performed on your knee in order to expose the articulation. Once the bones are completely on the open, the surgeon will use guides and high precision, special instruments to remove the damaged surfaces and remodel the ends of the bones in preparation to accept place the implants.
Then, the implants are fixed to the bones and probably some knee ligament adjustments will need to be made, in order to optimize the joint function.
When you are satisfied with the adjustment and function of the implants, the surgeon will close the incision.
It is possible that a special tube will be placed in your wound, so that all natural liquids that form in the surgical spot are drained completely. Then, you will be fixed with a sterile bandage and taken to the recovery room, where you will be object of strict vigilance.
Your intervention will take around an hour or three, depending on your individual circumstances.


After surgery:

As the effects of the anesthesia start to wear off, you will eventually regain consciousness. A nurse will accompany you, who may ask you to cough or take deep breaths to help clear out the lungs. They will give you painkillers as well.
When you are fully awakened, you will be moved to your hospital room. You will spend a few days where your knee will hurt and become swollen.

What can I expect after the surgery?

When you return to your hospital room, you will begin a hospital rehab program that will help you recover your knee strength, balance and movement width. This program, specially designed for you, may include the use of a continuous passive movement machine that prevents stiffness of the leg by automatically moving it.
Your physiotherapist will help you practice the appropriate exercises. 24 hours after the surgery, you will probably be asked to stand, and within 34 hours, you will begin taking a few steps with a walker's help.
After two to four days, or whenever your surgeon decides you have rested enough, you will be discharged from the hospital. Maybe they will move you to a nursering center for a few more days, if your surgeon deems best.
By the time you return to your home, you will have to keep on taking your regular medicines and performing the exercises your surgeon or physiotherapist has required of you. Normally they will remove all your bandages and stitches before your leave.
At home, you will have to keep on exercising. Your physiotherapist will teach you how to take good care of yourself, and maybe will keep on working with you.
Six weeks past from the surgery, most patients are able to walk with a cane. Within seven to eight weeks you will probably feel good enough to drive a car.
In most cases, a successful total knee replacement surgery will relieve your pain and stiffness, and should allow you to get back on most of your regular everyday activities. But even after attaining a full recovery, you will still have some restrictions.
Contact sports or knee-forcing movements like weightlifting are not embodied in everyday activities.



Why does my knee hurt?

The knee joint is made up of three bones. The femur - thigh bone - rests in the superior part of the tibia. When the knee is bent or straightened, the round-shaped edge of the femur rolls and slides over the tibia surface, which is relatively flat. The third bone is called rotula, and it is attached to the muscles that allow for knee straightening. The knee acts as a lever to reduce the effort of these muscles.
In a normal, healthy knee, the surfaces of the bones that converge in the articulation are even and hard. A buffer tissue layer - also known as cartilage - avoids direct contact between these bones. This strong layer of tissue allows the three bones to move around without any friction or wearing off of their surfaces. However, if this cartilage is damaged or worn, bones will rub each other, ultimately causing friction, pain, and over time, damaging of the bony surfaces.
The most common causes of cartilage damage are the several kinds of arthritis. There is no medication or treatment whatsoever that can regenerate the damaged cartilage.


This booklet is destined to give a general description of a total knee replacement intervention, and doesn't in any way intend to promote this kind of procedure or instruct about the pre-operational preparatives or the post-operational recovery process.