What Is Knee Joint Replacement?

Knee joint replacement is a procedure that replaces an injured or ailing knee with an artificial joint called a prosthesis.

The prosthesis is made of metal alloys, plastics, and polymers. It simulates the function of a knee. Replacement knees can be custom tailored to meet your needs. When selecting a prosthetic knee, your doctor will take into account your age, weight, activity level, and overall health (AAOS, 2011).

The procedure to remove your old knee and replace it with a prosthesis only takes about two hours, but recovery and rehabilitation can last months.

The procedure is also known as knee arthroplasty. Knee replacements are a very common surgery. According to the American Academy of Orthopedic Surgeons, more than 600,000 knee replacements are performed every year in the United States (AAOS, 2011).

Why Knee Joint Replacement Is Done

Damage from arthritis is the most common reason that knee joints have to be replaced. This includes both osteoarthritis and rheumatoid arthritis.

Knee replacement is usually only recommended after other, less invasive, treatment options have failed. First-line treatment options include losing weight, medications, physical therapy, and assistant devices such as a cane or a knee brace.

Key factors in determining if you’re a good candidate for knee joint replacement include:

  • how much your knee pain interferes with daily activities such as walking or climbing stairs
  • if your knee is deformed, bows, or “blows out” regularly
  • your age
  • your overall health

Knee surgery is typically used for people over the age of 55. Younger people who have their knees replaced will generally outlive their artificial knees and need a second replacement.

Each candidate for knee replacement surgery is evaluated on an individual basis.

The Risks of Knee Joint Replacement

Every medical procedure carries the risk of bleeding, blood clots, and infection. Your doctor will explain these risks and what you can do to minimize them. The American Academy of Orthopedic Surgeons states that less than two percent of the more than 600,000 people who have total knee replacements each year in the United States have serious complications (AAOS, 2011).

Complications associated with knee replacement surgery include:

  • artificial knee wears out over time
  • bleeding
  • blood clots in the leg or lungs
  • breathing problems caused by the anesthesia
  • heart attack
  • knee stiffness
  • nerve damage in the knee
  • stroke

Infection is an ongoing concern for people who receive artificial joints. As bacteria and other contaminants regularly flow through your blood, they can infect your artificial knee. If your knee becomes infected, parts of or the whole artificial knee must be replaced.

If you experience the following symptoms, contact your doctor immediately (Mayo):

  • chills
  • drainage from your surgical scar
  • fever over 100 degrees F
  • increasing pain, redness, swelling, and tenderness in the knee

How to Prepare for Knee Joint Replacement

Before surgery, your doctor will give you a general medical evaluation to assess your overall health and risk for anesthesia. This evaluation will include a full medical history, a physical examination, blood tests, X-rays, and other imaging tests.

You will give your doctor your complete medical history, including any prior surgeries and ongoing health conditions you have. Tell your doctor about any medication you are taking—including over-the-counter medicines and nutritional supplements—as you may have to stop taking some or all of them before your surgery.

Also, inform your doctor if you’ve ever had an allergic reaction to anesthesia. Your doctor will review your anesthesia options, based on your preferences and what he or she sees as appropriate for your situation. This could include general anesthesia, which means you are asleep during surgery, or anesthesia in your spine, which leaves you awake but pain free from the waist down.

Your doctor will give your surgeon the results of your medical evaluation, medical history, and your anesthesia choice.

Before surgery, you’ll want to prepare your home to accommodate your recovery. You can expect to walk with the aid of crutches or a walker for several weeks. You may need to install handles in showers and around the toilet. It’s good to have a chair and footrest available so you can elevate your leg. If possible, keep your living space on the first floor if you have a multistory house.

Your doctor and surgical team will give you full instructions on how to best prepare for surgery. It’s important to follow those instructions as closely as possible.

How Knee Joint Replacement Is Performed

When it’s time for your surgery, you’ll change into a hospital gown, be given an IV (to provide you with fluids and nutrients during the surgery), and asked to lay down on a bed with wheels. Just before surgery, you’ll be given the type of anesthesia you and your doctor have chosen and wheeled down to the operating room.

During the procedure, which lasts between one and two hours, your surgeon will make a long surgical cut above your knee. With the skin and muscle pulled back, he or she will cut away damaged cartilage and bone.

The new knee joint will be affixed to your femur (thighbone) and tibia (the main bone in your lower leg). They will be affixed with specialized cement, pins, and screws. When that is complete, the incision wound will be closed with stitches and bandaged.

You’ll be taken to a special recovery room where your vital signs will be continuously monitored.

Following Up After Knee Joint Replacement

After surgery, your leg will feel stiff, and you will experience some pain. This can be managed with painkillers administered intravenously. Along with pain medicine, you’ll also be given medication to prevent your blood from clotting.

Most people begin physical therapy the day after their surgery to promote blood flow to the tissues around the new knee. Your surgeon may recommend the use of a continuous passive-motion machine. This is a special brace-like device that continuously moves your knee in a gentle bending motion.

After a few days, if your surgeon is satisfied with the results of the surgery and deems you fit to leave, you will be released from the hospital.

Following your surgery, you’ll undergo months of physical therapy. Your surgeon and physical therapy team will design a program that’s right for you.