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Knee Replacement Surgery diagram of the human knee

Knee Replacement Surgery

The knee is the largest and strongest joint in the body. It is made up of the lower end of the femur (thighbone), the upper end of the tibia (shinbone), and the patella (kneecap). The ends of the three bones where they touch are covered with a smooth, slippery substance called articular cartilage that protects the bones and allows you to bend and straighten your knee. Two wedge-shaped pieces of cartilage called meniscus act as "shock absorbers" between your thighbone and shinbone. They are tough and rubbery, which helps cushion the joint and keep it stable. The knee joint is surrounded by a thin lining called the synovial membrane, which produces fluid that lubricates the cartilage and reduces friction.

Total knee replacement surgery may become necessary when severe degeneration of the joint occurs due to conditions such as arthritis, avascular necrosis (poor blood flow), trauma, and infection.


Also called "wear-and-tear" arthritis, osteoarthritis is a very common condition. Usually, people develop it in middle age or older. It causes pain, swelling, and stiffness that gradually worsens over time. It can occur in any joint in the body, but it is very common in the knee, causing the cartilage in the joint to slowly degenerate (wear away). If left untreated, the cartilage can wear away completely, causing bone-on-bone rubbing. Pain and joint stiffness make it hard to do everyday things like climbing stairs and walking, and it can also affect productivity at work. There is no cure for osteoarthritis, but early treatment is the best way to maintain an active, healthy lifestyle.

The other major types of arthritis that affect the knee are rheumatoid arthritis and posttraumatic arthritis. Rheumatoid arthritis is a chronic autoimmune disease that attacks multiple joints throughout the body, including the knee joint. It is symmetrical, which means it usually affects the same joint on both sides of the body. In rheumatoid arthritis the synovial membrane that covers the knee joint begins to swell, resulting in knee pain and stiffness. Posttraumatic arthritis develops as a result of an injury such as a broken bone.

The most common symptoms of knee arthritis are pain (which usually develops gradually) and inflammation. Other symptoms may include:

  • A stiff and swollen joint, making bending and straightening the knee difficult
  • Pain that flares up after vigorous activity, such as exercise
  • "Locking" or "sticking" of the knee during movement, caused by loose cartilage fragments. The knee might creak, click, snap or make a grinding noise.
  • A feeling of weakness or buckling in the knee due to pain
  • Increased joint pain with rainy weather

Diagnosing knee arthritis begins with:

Physical Exam


Personal and Family Medical History: Your doctor will likely ask you a series of questions relating to your personal medical history and your family's medical history.

Your doctor will perform tests to assess:

  • Joint swelling, warmth, or redness
  • Tenderness around the knee
  • Range of motion
  • Instability of the joint
  • If there is a grating sensation when you move the joint
  • Pain when pressure is placed on the knee
  • Gait (walking) issues
  • Involvement of other joints (an indication of rheumatoid arthritis)

Imaging Tests




Other imaging tests may be performed to better determine the condition of the bone and soft tissues of your knee. These include:

Magnetic resonance imaging (MRI)


Computed tomography (CT) scan


Bone scans


Laboratory Tests

Blood tests


There is no cure for knee arthritis but there are a number of treatments that may help relieve the pain and disability it can cause.

Nonsurgical Treatment

As with other arthritic conditions, initial treatment of knee arthritis is nonsurgical. Your doctor may recommend a range of treatment options.

Activity modification: Physicians may prescribe general lifestyle changes to a patient, in order to help relieve the symptoms of their condition and improve their overall physical function and well-being. Depending on the medical condition being treated, activity modification may include: decreasing or increasing one's level of physical activity; added rest; beginning a new activity or exercise program; changing sleep habits; or modifying one's physical environment at home, in their vehicle, or at work.

Some changes in your daily life can protect your knee and slow the progress of arthritis:


Physical therapy

Sometimes referred to simply as "PT," this is a type of rehabilitative treatment that uses specially designed exercises and equipment to help patients preserve, regain, or improve their physical abilities following injury, disability, disease, or surgery. Physical therapy can include therapeutic exercise, massage, walking aids, and patient education and training.

Walking aids


Other nonsurgical approaches may include:

  • Applying heat or ice
  • Pain-relieving ointments or creams
  • Wearing elastic bandages to provide support to the knee
  • Medications such as:
    • Over the counter medication such as acetaminophen
    • Nonsteroidal anti-inflammatory drugs (NSAIDs): A class of medications, including but not limited to aspirin, naproxen, and ibuprofen, that are used for reducing pain and redness, swelling, and heat (inflammation) in arthritis and other painful inflammatory disorders.
    • Corticosteroids: Cortisol is a naturally-occurring hormone in the body that can affect immune cells. Corticosteroids can be given orally (as a pill) or topically (as a cream, gel, or ointment). Because topical corticosteroids are applied directly to the skin and not circulated throughout the body, patients being treated with them may experience fewer side effects.
  • Alternative therapies including acupuncture and magnetic pulse therapy

Knee Replacement Surgery

Your doctor may recommend surgery if your knee pain causes disability and is not relieved with nonsurgical treatment. There are many different types of knee surgery available. There are also many different materials that may make up a total joint replacement - including metal and plastic - and the best solution varies from person to person. Your doctor will discuss all of your options with you.


X-ray image showing an artificial knee joint replacement in a patient who suffered from osteoarthritis. 

This surgery consists of removing the damaged parts of the knee and replacing it with a smooth artificial surface that is designed to mimic the rolling, gliding motion of a healthy knee. The new prosthesis is customized to the individual, taking into consideration their age, weight, general health, and activity level. The goal of surgery is to alleviate pain and restore function in the damaged knee joint.

Partial Knee Replacement Surgery

Also called "knee resurfacing," this is an alternative to total knee replacement. It allows the patient to retain part of their original knee joint while also receiving some new, artificial parts. Partial knee replacement can be a good option for patients with active lifestyles, allowing them to return to their normal activity levels prior to the onset of their knee pain.

After any type of knee surgery, there is a period of recovery. Your recovery time and rehabilitation will depend on the type of surgery you had. Your doctor may recommend physical therapy as well as use of walking aids such as a walker, crutches, or a cane. After a period of time, you should be able to perform simple, daily tasks again with less pain.

If you would like additional information about joint replacement surgery at BMC or wish to make an appointment, please call 617.830.3973.