Rheumatoid arthritis (RA) is a type of arthritis where your immune system attacks healthy tissues in your joints.

It usually affects the joints in the hands and feet, but it can also affect the knees and other joints. RA is often symmetrical as well. For example, this means both knees would be affected.

More than 1.5 million Americans have RA. But your knees may not start showing signs of RA until much later, even years after symptoms begin to appear.

Untreated RA can cause long-term and progressive inflammation that can ultimately lead to joint damage. Nearly 60 percent of people with RA report not being able to work after 10 years due to their symptoms if they don’t get treatment.

Let’s look into how RA can affect your knees, how to recognize the symptoms, and how you can get it diagnosed and treated before it causes damage.

In RA, your immune system attacks and damages the joint cell lining and capsular tissue that surrounds the joint. It’s the same with RA in your knees:

  1. Immune cells target the synovial membrane that lines the knee joint. This membrane protects the cartilage, ligaments, and other tissues of the knee joint. It also makes synovial fluid, which lubricates the joint to allow for smooth movement.
  2. The membrane swells. This causes pain from the inflammation of the tissue. Knee movement is also limited as the swollen membrane takes up more space in the knee area.

Over time, the swelling can damage the cartilage and ligaments of the knee joints. These help your knee move and keep bones from grinding on each other.

As they become damaged, cartilage wears away and bones start to push and grind against each other. This results in pain and bone damage.

Damage from RA also raises the risk of breaking or wearing down bones more easily. This makes it difficult or impossible to walk or stand without pain or weakness.

A hallmark symptom of RA is tenderness, pain, or discomfort that gets worse when you stand, walk, or exercise. This is known as a flare-up. It can range from a mild, throbbing pain to an intense, sharp pain.

More common symptoms of RA in your knees include:

Other symptoms of RA you might experience include:

  • exhaustion
  • tingling or numbness in the feet or fingers
  • dry mouth or dry eyes
  • eye inflammation
  • losing your appetite
  • abnormal weight loss

Here are a few of the methods your doctor will use to diagnose RA in your knees:

Physical examination

In a physical exam, your doctor may gently move your knee to see if what causes any pain or stiffness. They may ask you to put weight on the joint and listen for grinding (crepitus) or other unusual noises in the joint.

They’ll ask general questions about your symptoms and overall health and medical history, too.

Blood tests

C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR) tests can measure levels of antibodies that indicate inflammation in your body that can help diagnose RA.

Imaging tests

Your doctor will likely use imaging tests to get a better look at the joint:

  • X-rays can show overall damage, abnormalities, or changes in the shape and size of the joint and joint space.
  • MRIs provide detailed, 3-D images that can confirm damage to the bones or tissues in the joint.
  • Ultrasounds can show fluid in the knee and inflammation.

Depending on the severity and progression of RA in your knee, you may only need over-the-counter (OTC) medications.

In advanced cases, you may need surgery to restore mobility or reduce pain and stiffness in your knee joint.

Treatments for RA that don’t require surgery include:

Surgical options for RA include:

  • Repairing damaged ligaments or tendons can strengthen your knee joint and reverse damage from inflammation.
  • Reshaping the knee bones or joint tissue (osteotomy) can reduce pain from loss of cartilage and grinding of the knee bone.
  • Replacing the knee joint with an artificial plastic or metal prosthetic joint can restore strength and mobility to the joint. This is a highly successful option — 85 percent of replaced joints still function well after 20 years.
  • Removing the synovial membrane (synovectomy) around the knee joint can reduce pain from swelling and movement, but it’s rarely done today.

Here are some other proven home and lifestyle remedies you can try to reduce the symptoms of RA in your knees:

  • Lifestyle changes. Try low-impact exercises like swimming or tai chi to take pressure off your knees. Exercise for shorter periods of time to reduce the chance of a flare-up.
  • Dietary changes. Try an anti-inflammatory diet or natural supplements like glucosamine, fish oil, or turmeric to reduce symptoms.
  • Home remedies. Put a warm compress on the joint to help restore some mobility and relieve swelling, especially in combination with an NSAID or other OTC pain reliever. like acetaminophen.
  • Assistive devices. Try customized shoe inserts or insoles. You can also use a cane or wear knee braces to reduce pressure on your knee joints to make it easier to walk.

See your doctor if you experience any of the following related to your knee joints:

  • inability to walk or do your usual daily activities due to joint pain or stiffness
  • intense pain that keeps you up at night or affects your overall mood or outlook
  • symptoms that interfere with your quality of life, such as keeping you from doing your favorite hobbies or seeing friends and family

Seek immediate medical care if you experience significant knee swelling or hot, painful joints. This may suggest an underlying infection that can lead to joint destruction.

RA can affect your knees just like any other joint in your body and cause pain, stiffness, and swelling that can get in the way of your everyday life.

The key is to get treatment early and often. The joint can become damaged over time and limit your movement, making it hard to walk or stand.

See your doctor if the pain is interfering with your quality of life and making it hard to do basic tasks that involve your knees.