Knee replacement, or knee  arthroplasty , is a surgical procedure to replace the weight-bearing surfaces of the knee joint to relieve pain and disability. It is most commonly performed for  osteoarthrites  and also for other knee diseases such as  rheumatoid arthritis and  Psoriatic arthritis . In patients with severe deformity from advanced rheumatoid arthritis  , trauma, or long-standing osteoarthritis, the surgery may be more complicated and carry higher risk. Osteoporosis   does not typically cause knee pain, deformity, or inflammation and is not a reason to perform knee replacement.

Other major causes of debilitating pain include meniscus tears, cartilage defects, and ligament tears. Debilitating pain from osteoarthritis is much more common in the elderly.

Knee replacement surgery can be performed as a partial or a total knee replacement. In general, the surgery consists of replacing the diseased or damaged joint surfaces of the knee with metal and plastic components shaped to allow continued motion of the knee.

The operation typically involves substantial postoperative pain, and includes vigorous physical rehabilitation. The recovery period may be 6 weeks or longer and may involve the use of mobility aids (e.g. walking frames, canes, crutches) to enable the patient’s return to preoperative mobility.

Cause

The most common cause of chronic knee pain and disability is arthritis. Although there are many types of arthritis, most knee pain is caused by just three types: osteoarthritis, rheumatoid arthritis, and post-traumatic arthritis.

  • Osteoarthritis. This is an age-related “wear and tear” type of arthritis. It usually occurs in people 50 years of age and older, but may occur in younger people, too. The cartilage that cushions the bones of the knee softens and wears away. The bones then rub against one another, causing knee pain and stiffness.
  • Rheumatoid arthritis. This is a disease in which the synovial membrane that surrounds the joint becomes inflamed and thickened. This chronic inflammation can damage the cartilage and eventually cause cartilage loss, pain, and stiffness. Rheumatoid arthritis is the most common form of a group of disorders termed “inflammatory arthritis.”
  • Post-traumatic arthritis. This can follow a serious knee injury. Fractures of the bones surrounding the knee or tears of the knee ligaments may damage the articular cartilage over time, causing knee pain and limiting knee function.
Orthopedic Evaluation

An evaluation with an orthopedic surgeon consists of several components:

  • A medical history. Your orthopedic surgeon will gather information about your general health and ask you about the extent of your knee pain and your ability to function.
  • A physical examination. This will assess knee motion, stability, strength, and overall leg alignment.
  • X-rays. These images help to determine the extent of damage and deformity in your knee.
  • Other tests. Occasionally blood tests, or advanced imaging such as a magnetic resonance imaging (MRI) scan, may be needed to determine the condition of the bone and soft tissues of your knee.
(Left) In this x-ray of a normal knee, the space between the bones indicates healthy cartilage (arrows). (Right) This x-ray of a knee that has become bowed from arthritis shows severe loss of joint space (arrows).

Your orthopedic surgeon will review the results of your evaluation with you and discuss whether total knee replacement is the best method to relieve your pain and improve your function. Other treatment options — including medications, injections, physical therapy, or other types of surgery — will also be considered and discussed.

In addition, your orthopedic surgeon will explain the potential risks and complications of total knee replacement, including those related to the surgery itself and those that can occur over time after your surgery.

Your Surgery

You will most likely be admitted to the hospital on the day of your surgery.

Anesthesia

After admission, you will be evaluated by a member of the anesthesia team. The most common types of anesthesia are general anesthesia (you are put to sleep) or spinal, epidural, or regional nerve block anesthesia (you are awake but your body is numb from the waist down). The anesthesia team, with your input, will determine which type of anesthesia will be best for you.

Procedure

The procedure itself takes approximately 1 to 2 hours. Your orthopaedic surgeon will remove the damaged cartilage and bone, and then position the new metal and plastic implants to restore the alignment and function of your knee.

Different types of knee implants are used to meet each patient’s individual needs.
(Left) An x-ray of a severely arthritic knee. (Right) The x-ray appearance of a total knee replacement. Note that the plastic spacer inserted between the components does not show up in an x-ray.

After surgery, you will be moved to the recovery room, where you will remain for several hours while your recovery from anesthesia is monitored. After you wake up, you will be taken to your hospital room.