A Guide to Knee Arthritis and Knee Osteoarthritis

Medically Reviewed By Daniel Wiznia, MD
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Knee arthritis is a condition involving the knee joint. Symptoms include not only pain but also tenderness, swelling, and stiffness. Knee arthritis can make daily activities that involve walking or standing challenging. Osteoarthritis is the most common type of knee arthritis. Treatments can help manage symptoms and slow the progression. 

According to the Arthritis Foundation, about 14 million adults in the United States have knee osteoarthritis with symptoms. Other forms of arthritis can also affect the knees, including rheumatoid arthritis, psoriatic arthritis, and post-traumatic arthritis.

Here is a look at types of knee arthritis, what causes knee arthritis, symptoms, and treatments for different types of knee arthritis.

What is knee arthritis?

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Knee arthritis is a condition that causes pain, stiffness, and swelling of the knee joint. Arthritis can occur in any joint. The knee joint is one of the largest and most complex joints in the body. As a hinge joint, it moves back and forth like a door on a hinge. It is also a weight-bearing joint. All that movement and stress make it vulnerable to arthritis.

Osteoarthritis is the most common form of arthritis, and the knees are one of the most likely places to have it. Osteoarthritis is often called “wear-and-tear” arthritis because it develops when the cartilage in joints, which cushions the bones, wears away over time.

As the cartilage thins, the bone ends grind against each other, causing knee pain, stiffness, and reduced range of motion that comes with osteoarthritis.

The pain and stiffness of knee arthritis can affect your mobility. A compensatory gait — walking in a way to avoid knee pain — can lead to skeletal imbalances and chronic back pain. It can affect your sleep and result in fatigue.

People with more severe rheumatoid arthritis can experience malnutrition linked to immune system function.

What are the types of knee arthritis?

There are several types of knee arthritis. They have similar symptoms but different causes. The different types of knee arthritis include:

  • Osteoarthritis: This degenerative condition causes cartilage and bone to wear away due to wear and tear.
  • Rheumatoid arthritis: This chronic systematic autoimmune disease causes joint inflammation and more severe symptoms compared with osteoarthritis.
  • Psoriatic arthritis: This autoimmune disorder is the skin condition psoriasis that affects the knee and other joints.
  • Post-traumatic arthritis: This type of arthritis develops quickly after an injury to the joint and may be temporary. Experts consider it a form of osteoarthritis.

What are the symptoms of knee arthritis?

Although the different types of arthritis that affect the knee are separate conditions, they have many similar symptoms. However, unlike osteoarthritis and post-traumatic arthritis limited to one joint like the knee, rheumatoid and psoriatic arthritis often affect several joints.

In severe cases, the joints may have permanent damage and change shape.

Knee arthritis symptoms usually come on gradually, as the cartilage wears away or the inflammation begins.

Common symptoms of knee osteoarthritis and post-traumatic arthritis

Knee arthritis symptoms due to osteoarthritis include:

  • knee pain that starts gradually and worsens with activity
  • pain, stiffness, and swelling after inactivity, such as long periods of sitting or resting
  • soreness or pain after overuse
  • sensation of grating or rubbing in the knee
  • decreased flexibility

You may also develop bone spurs, which may or may not cause symptoms.

Common symptoms of rheumatoid and psoriatic arthritis

Rheumatoid and psoriatic arthritis are inflammatory rather than degenerative conditions. These two types of arthritis have similar symptoms to osteoarthritis but also some differences.

Symptoms of rheumatoid and psoriatic arthritis include not only pain but also:

  • stiffness, particularly in the morning
  • swelling
  • fatigue
  • loss of appetite in rheumatoid arthritis
  • skin discoloration and warmth in psoriatic arthritis
  • enthesis in psoriatic arthritis, which is tissue inflammation between joints
  • fingernail and toenail changes with psoriasis

When to contact a doctor for symptoms of arthritis

Symptoms of knee arthritis can indicate the importance of getting medical care. An accurate diagnosis and early treatment may:

  • reduce pain
  • slow progression
  • prevent disability
  • maintain health-related quality of life

In many cases, a doctor can diagnose knee osteoarthritis based on: 

  • symptoms
  • physical exam
  • medical history
  • X-ray or other imaging test results

A doctor may order blood tests to check for specific markers of rheumatoid or psoriatic arthritis.

What causes knee arthritis?

The cause of knee arthritis depends on the type of arthritis.

Osteoarthritis occurs most commonly in joints people use the most, such as the knee. The cartilage degenerates over time and becomes rough, rubbing against the inside of the joint. Eventually, the cartilage may wear away completely.

Post-traumatic knee arthritis is a form of osteoarthritis, but injury damages the joint rather than wear and tear. Blows to the knee from contact sports or car accidents are examples of injuries that can cause this type of arthritis.

Rheumatoid and psoriatic arthritis result from autoimmune diseases. Your body’s immune system, which usually guards your body against organisms that can make you sick, begins to attack healthy cells in your body. Some autoimmune diseases cause inflammation in your joints. As the inflammation builds up, it causes pain and swelling.

What are the risk factors for knee arthritis?

Age is the main risk factor for developing osteoarthritis in the knee. Obesity is another major factor.

There can be a link between rheumatoid arthritis and your genetic makeup. About one-third of people with psoriasis develop psoriatic arthritis. Rheumatoid and psoriatic arthritis can develop at any age but are more common in adults ages 30–50.

Risk factors for knee osteoarthritis include:

  • female sex
  • overweight or obesity
  • history of knee injury
  • repetitive stress, such as doing a job that requires you to squat or bend your knees regularly
  • formation of your leg bones, which may put pressure on your knees

Risk factors for rheumatoid arthritis include:

  • female sex
  • family history of rheumatoid arthritis
  • smoking
  • obesity

The risk factors for psoriatic arthritis include severe skin psoriasis and obesity or metabolic syndrome, which increases the risk of certain chronic conditions.

How can you reduce your risk of knee arthritis?

Some risk factors, including genetics and family history, are out of your control. However, you may be able to lower your risk of knee arthritis by:

  • maintaining a moderate weight
  • taking care of knee injuries and allowing your knee to fully heal before resuming usual activities 
  • considering quitting smoking
  • using protective gear when participating in activities that increase your risk of knee injuries
  • exercising and strengthening your leg muscles to reduce stress on the knees, particularly if you must squat or bend repetitively
  • following your treatment plan if you have rheumatoid arthritis or psoriasis

If you experience symptoms of knee arthritis or have any risk factors for developing arthritis, speak with your doctor about steps you can take to help prevent knee arthritis or slow its progression.

How is knee arthritis treated?

Medical care cannot cure arthritis yet, but active treatment can help you manage arthritis symptoms and perhaps slow down the progression. Treatment depends on the type of arthritis, and some strategies overlap. Treatments include: 

Exercise and strength training 

Building up your leg muscles can help protect your knees and reduce the strain and potential damage to the joint. Experts often recommend tai chi and yoga because they do not put extra stress on your joints. They also help improve balance and reduce mental stress.

Weight management 

Extra weight puts added stress on knee joints. This can accelerate tissue breakdown and cause pain and swelling. Maintaining a moderate weight may reduce pain and other arthritis symptoms.

Physical therapy

A physical therapist can help you regain muscle strength in your legs with special exercises and an at-home exercise plan.

Medication

Medications, including nonsteroidal anti-inflammatories, can help reduce swelling and pain in your knee. In some cases, your doctor may recommend cortisone or a steroid knee injection to decrease knee swelling.

If you have rheumatoid or psoriatic arthritis, a class of drugs called biologics may help manage the inflammation in your joints.

Artificial joint fluid

Artificial joint fluid — hyaluronic acid — is injectable directly into your knee. Hyaluronic acid injections can create a barrier to inflammation and provide temporary lubrication inside the knee joint. They are not effective for everyone with knee arthritis and you will need repeat injections regularly.

Surgery

Your doctor may recommend contacting an orthopedic surgeon if arthritis in your knee is severe. Possible surgical procedures include:

  • Synovectomy: This procedure removes the inflamed joint lining, called the synovium.
  • Osteotomy: This is bone realignment, which may be an option if only one side of your knee has damage. A surgeon reshapes the bones in the knee to redistribute your body’s weight on the joint.
  • Knee replacement: A partial or total knee replacement removes the damaged knee or part of the knee and replaces it with a plastic or metal joint.

Following a treatment plan for knee arthritis can help improve your health-related quality of life, may slow the condition’s progression, or prevent complications. Talk with your doctor about the different options that may be available to you.

What are the potential complications of knee arthritis?

Arthritis is a chronic condition. Left untreated, one complication of knee arthritis includes increased pain, which can lead to health concerns that may affect your quality of life, including mobility difficulties and insomnia. These health concerns and the pain may make it challenging to participate fully in some physical activities.

Severe knee arthritis can cause disability and changes in your knee form. Some disabilities may make it difficult to work, but you can talk with your doctor about alternatives for your specific situation to help you participate fully in your daily activities.

Knee arthritis treatments may also increase your risk of complications, such as medication side effects and surgical problems.

It is important to discuss the benefits and risks of all treatment options with your doctor.

Many people with knee arthritis respond well to treatment, and the benefits to your health and well-being usually outweigh the risks of not treating the condition.

Frequently asked questions

Here are some other questions people commonly ask about knee arthritis.

Is walking good for arthritis in the knee?

Walking is good for all types of knee arthritis. Walking can help you maintain a moderate weight, which can put less stress on weight-bearing joints like the knee. It can also build lower body muscles that support the knee. Other low impact exercises, such as stationary bike, are also good for the knee.

How do you get rid of knee pain fast?

If your knee is sore, give it a bit of rest. Try to keep the weight off it for 1 or 2 days. Try an ice pack on your knee for up to 20 minutes every 2–3 hours. Avoid putting the ice directly on your skin. Instead, wrap the ice pack in a thin towel or other material.

Is it possible to reverse knee arthritis?

The damage to the knee from arthritis is currently irreversible, but it is treatable and manageable. You may also be able to slow down the progression of knee arthritis by maintaining a moderate weight and exercising.

Can knee arthritis cause calf pain?

Pain and stiffness from knee arthritis may limit movement. This can affect leg muscles and may cause weakness and atrophy. Treatment for knee arthritis includes exercise to strengthen leg muscles, taking medication to reduce pain and swelling, or surgery.

Summary

Knee arthritis causes pain and stiffness and is common. There are different types of knee arthritis, including osteoarthritis from wear and tear or injury, and inflammatory arthritis due to autoimmune diseases.

Some symptoms vary, but all types of knee arthritis cause stiffness and pain. Treatment depends on the arthritis type and cause.

Treatment options include medication, physical therapy, and surgery. Your doctor or physical therapist can recommend an exercise program to strengthen muscles, protect knee joints, and maintain a moderate weight.

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Medical Reviewer: Daniel Wiznia, MD
Last Review Date: 2022 Jul 25
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