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What Is Knee Arthritis?

The knee is one of the joints most commonly affected by arthritis, a general term for more than 100 conditions that cause joint pain and inflammation, and is the joint most often affected by osteoarthritis–the most common type of arthritis. A 2017 study published in Proceedings of the National Academy of Sciences suggests that the occurrence of knee osteoarthritis has doubled since the mid-20th century, an increase that cannot be wholly explained by higher obesity rates and longer lifespans.

Common Types of Knee Arthritis

Osteoarthritis is the most common type of knee arthritis. It is a degenerative disease in which the cartilage wears down in the knee, causing painful bone-on-bone contact within the joint.

Post-traumatic arthritis is another common type of knee arthritis and occurs after an injury, which can damage cartilage and create more wear and tear on the joint. This makes the knee more likely to become arthritic.

Another common type of arthritis that affects the knee is rheumatoid arthritis (RA), an autoimmune condition in which the body’s immune system attacks and damages tissue in the knee. RA usually affects both knees at the same time.

Symptoms of Knee Arthritis

Pain and swelling of the knee are the main symptoms of knee arthritis. The knee may be stiff and unable to fully extend. The pain may be worse in the morning, after resting, after activity or with rainy weather. Fragments of cartilage may further hinder the knee, causing it to lock or creating a clicking, snapping or grinding noise.


A doctor will perform a physical exam, looking for signs such as:

  • Instability of the knee
  • Pain
  • Problems walking
  • Range of motion of the joint
  • Swelling
  • Tenderness

A medical history may be useful to determine if there was an injury or accident that could be causing post-traumatic arthritis, and since some forms of arthritis run in families, a family history of arthritis can help narrow down a diagnosis.

Other tests may also be helpful to confirm a knee arthritis diagnosis. An X-ray can show changes in the bone or bone spurs that may be indicative of arthritis, while a magnetic resonance imaging (MRI) or computed tomography (CT) scan can show soft tissue deterioration. Blood tests can be useful in detecting RA.


Treatment of knee arthritis will depend on what type of arthritis is present and can include both surgical and nonsurgical options. Common arthritis treatments include:

If you are seeking treatment for your knee arthritis, follow the link below and answer a few short questions. Someone will get back to you as soon as possible. Thank you for choosing Summit Health.

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