Knee Replacement Surgery

What is knee replacement surgery?

When your knee is badly damaged by disease or injury, an artificial knee replacement may be considered. During knee replacement surgery, your joint surfaces are replaced by prostheses. These are plastic and metal parts that are used to replace your joint surfaces.

Why might I need knee replacement surgery?

Osteoarthritis is the most common problem that leads to knee replacement surgery. This is a “wear and tear” joint disease that affects mostly middle-aged and older adults. Osteoarthritis leads to the breakdown of joint cartilage, and then bone, in your knees.

Other
forms of arthritis, such as rheumatoid arthritis and arthritis caused by a knee injury,
can also lead to degeneration of your knee joint. Fractures, torn cartilage, or torn
ligaments also can lead to permanent damage to your knee joint over time.



The decision to replace the painful knee with an artificial one is a joint decision between you and your healthcare provider. Other treatments may be used first. These include lubricating injections, steroid injections, physical therapy, assistive walking devices, and anti-inflammatory medicines that help with pain and swelling.

How do I get ready for knee replacement surgery?

In
addition to taking a complete medical history, your healthcare provider will do a
complete physical exam. He or she may also take X-rays, urine tests, and blood tests to
check your overall health before surgery. You may also meet with a physical therapist to
discuss rehabilitation after the surgery, equipment you may need (such as crutches or a
walker), and changes needed at home (for instance, toilet seat risers, tub or shower
safety bars, and secure handrails at stairs).

While
the chance for infection after knee replacement is very low, it can occur. You may be
asked to see your dentist before surgery, so that any major dental procedures you might
need (such as tooth extractions and periodontal work) can be done before your total knee
replacement surgery. This helps reduce your risk for infection.

Tell your healthcare provider about all prescription and over-the-counter medicines and any vitamins, herbs, and supplements that you are taking. Some of these may affect things like healing and blood clotting, so you may need to stop taking them before surgery.

Your
healthcare provider will tell you not to eat or drink anything for several hours before
the surgery. You will probably have to stay in the hospital for several days, and you
will not be allowed to drive for some time after surgery. You will probably need some
help at home (with things like bathing, dressing, cleaning, and shopping) for a short
time after surgery, so you may want to arrange this ahead of time.

Talk to your healthcare provider so you know exactly what you need to do before your procedure.

What happens during knee replacement surgery?

Although each procedure varies, generally, surgery to replace your knee lasts about 2 hours. During surgery, you may be under general anesthesia (medicine that puts you to sleep and keeps you from feeling pain during the surgery). Your healthcare provider may also give you a nerve block, or spinal or epidural anesthesia. These numb the lower half of your body so you don’t feel pain. With these medicines, you can remain awake.

After the damaged bone and cartilage of your knee are removed, your orthopedic surgeon will put your new artificial knee in place.

The
2 most common types of knee prostheses used in knee replacement surgeries are cemented
prosthesis and uncemented prosthesis. Sometimes, a combination of the 2 types is used. A
knee prosthesis is made up of metal and ceramic or plastic. A cemented prosthesis is
attached to the bone with a type of epoxy. An uncemented prosthesis attaches to the bone
with a fine mesh of holes on the surface. The bone grows into the mesh and attaches to
the prosthesis.

The
prosthesis (artificial knee) is made up of these 3 components:

  • Tibial component (to replace the top of your tibia, or shin bone)
  • Femoral
    component (to replace your 2 femoral [thighbone] condyles and the patella
    groove)
  • Patellar component (to replace the bottom surface of the kneecap that rubs against your thighbone)



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