What to Know About Joint Effusion (Swollen Joint)

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Joint effusion is swelling of the tissues in or around your joint because of extra fluid. Joint effusion can cause a "puffy" appearance to your joints along with symptoms like pain and stiffness. Common causes of joint effusion are infections, arthritis, or injury (including repetitive use injuries).

When the buildup of fluid comes with inflammation of the connective tissues lining a joint, it is called joint effusion with synovitis.

Joint effusion tends to affect larger joints such as the knee (sometimes called "water on the knee"), shoulder, elbow, or ankle. However, this is not the same as edema, which is the generalized build-up of fluid in tissues.

This article explains what joint effusion is, its causes and symptoms, and how it can be treated.

common joint effusion symptoms

Verywell / Emily Roberts

Joint Effusion Symptoms

Regardless of what is causing the accumulation of fluid in a joint, the symptoms are more or less the same. They can range in severity from mild to debilitating.

Classic symptoms of joint effusion include:

  • Swelling (ranging from mild puffiness to severe swelling)
  • Pain (ranging from a dull throb to sharp, stabbing pains that interfere with mobility)
  • Redness and warmth (associated with inflammation and/or infection)

Depending on what is causing joint effusion, there can also be other symptoms like:

  • Bruising and bleeding in the joint space (such as caused by an injury)
  • Fever, chills, malaise, and weakness (if an infection is involved)
  • A fluid-filled nodule called Baker's cyst (caused by accumulated fluids that cannot be reabsorbed)
  • Progressive muscle loss (called arthrogenic muscle inhibition, also the result of an injured joint)

When Is Joint Effusion an Emergency?

You need emergency care for a swollen joint if:

  • It’s caused by an injury like a broken bone or torn ligament.
  • You cannot move the joint at all.
  • You cannot put any weight on the joint.
  • The joint looks red and feels hot to the touch.
  • You cannot feel the area around the joint.
  • You also have a fever.

What Causes Joint Effusion?

Joint effusion is a sign of joint inflammation and can be classified as either infectious (septic) or noninfectious (aseptic).

Joint effusion caused by infection is referred to as septic arthritis. Aseptic joint effusion can be related to an injury or arthritis.

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This video has been medically reviewed by Oluseun Olufade, MD.

Infection

Septic arthritis is most commonly caused by a joint infection. The infection can come from an open wound like a deep laceration or an invasive medical procedure (including a joint replacement).

An infection in the bloodstream (systemic infection) can sometimes take hold in a joint and cause swelling and effusion in just that area (localized). 

Signs of Septic Arthritis

When joint effusion is caused by an infection, the symptoms are typically intense and come on fast. The condition will usually be extremely painful, particularly with movement. Redness, warmth, and fever are also common.

Certain factors increase the risk of septic arthritis, including:

  • Older age
  • Diabetes
  • Intravenous (IV) drug use
  • Joint replacement
  • Recent joint surgery
  • Arthritis
  • A compromised immune system (such as seen in people with HIV, organ transplant recipients, and people undergoing chemotherapy)

Injury

Injury is a common cause of joint effusion, especially in the knees. Injuries from a car accident, severe fall, or blunt force impact can lead to an effusion.

These injuries can also involve bone, connective tissues (such as tendons and ligaments), or joint cartilage (like the meniscus). Repeated stress on a joint can also cause effusion. This type of overuse injury happens when a person is repeating a movement a lot and for a long time, and is usually related to an occupation or sports.

If the joint effusion is caused by a repetitive stress injury, other conditions like bursitis (inflammation of the fluid-filled sac that cushions a joint) and tenosynovitis (inflammation of the tendon sheath where a muscle attaches to a bone) are also common.

Pain, swelling, stiffness, and trouble extending or rotating the joint are other common symptoms of injury-related effusion.

Arthritis

Joint effusion is common in people with arthritis. The condition can be chronic (comes on slowly and is progressive) or acute (comes on fast and is severe).

There are two main categories of arthritis: osteoarthritis (a non-inflammatory form of arthritis that’s also called "wear-and-tear arthritis") and autoimmune arthritis (a group of inflammatory autoimmune disorders in which the immune system attacks its own joints).

With osteoarthritis, joint effusion most commonly occurs when there is extensive joint damage. The knee is the joint that is most often affected.

With autoimmune arthritis, joint effusion can be chronic but most often occurs in acute episodes (exacerbations or “flare-ups”). Some autoimmune conditions that can cause joint effusion are:

  • Rheumatoid arthritis. The most common form of autoimmune arthritis. It typically affects joints on both sides of the body.
  • Gout. An autoimmune condition that causes swelling and pain, mainly in the big toe. The inflammation is caused by the formation of uric acid crystals in the joint space.
  • Juvenile idiopathic arthritis. An autoimmune form of arthritis that develops in children.
  • Psoriatic arthritis. An autoimmune form of arthritis that goes along with the chronic skin condition psoriasis.

Joint Effusion Diagnosis

Diagnosing joint effusion may involve a physical exam, imaging tests, and a lab evaluation of the fluid in your joint. In addition, a healthcare provider will want to talk to you about your medical history, current health, and other symptoms.

Physical Examination

Your provider will look at your joint carefully. They will touch (palpate) and work (manipulate) the joint to determine the severity of the condition and the possible causes.

Here are some things your provider might notice during the exam:

  • With arthritis, the lubricating tissue between the joints (synovium) will often feel "boggy" or "mushy." With the exception of gout, the swelling from most types of arthritis will be gradual rather than swift.
  • Joint infections tend to develop rapidly and cause severe pain and redness.
  • torn ligament or knee fracture will almost always cause swelling and the inability to bear weight on the joint.

Imaging Tests

After examining your knee, a provider may order imaging tests to see what’s causing the effusion. Each test has its benefits and limitations.

The imaging tests may include:

  • Ultrasonography. This non-invasive imaging tool uses sound waves to help providers see bone and connective tissues. It can be used to confirm arthritis or inflammation of tendons or ligaments. However, it is less able to visualize soft tissues than other forms of imaging.
  • X-rays and computed tomography (CT). Both of these imaging techniques use ionizing radiation to create images of bone and connective tissue. With CT, multiple X-ray images are combined into three-dimensional "slices" of a body part. CT and X-rays are often best for diagnosing bone fractures and arthritis.
  • Magnetic resonance imaging (MRI). This imaging technique uses powerful magnetic fields and radio waves to create highly detailed images of soft tissue. MRI can be useful for seeing cartilage, ligaments, and other joint structures that the other tests cannot pick up as well. 

Joint Fluid Analysis

Your provider may want to drain (aspirate) fluid from a swollen joint. This can help reduce pressure and relieve pain but can also provide valuable information about the cause of the effusion.

The fluid (synovial fluid) is removed with a needle and syringe during a procedure known as arthrocentesis. Synovial fluid is usually clear with the consistency of an egg white. Any changes in the appearance, texture, color, or composition of the fluid can provide clues about what might be causing the effusion in the joint. 

A lab can analyze the fluid to determine if there are excess white blood cells (a sign of infection), uric acid crystals (a sign of gout), or other abnormalities that may narrow the possible causes.

How Is Joint Effusion Treated?

The standard first-line treatments for joint effusion include rest, ice application, immobilization, and a nonsteroidal anti-inflammatory drug (NSAID) like Advil (ibuprofen) or Aleve (naproxen).

If the swelling is severe, your provider may want to aspirate the joint to reduce pressure. They may give you a cortisone injection after the procedure to reduce inflammation and pain.

Infections can usually be treated with a 14-day course of a broad-spectrum oral antibiotic like ciprofloxacin. Serious infections like systemic gonorrhea or methicillin-resistant Staphylococcus aureus (MRSA), may require a two- and four-week course of intravenous (IV) antibiotics.

If you have rheumatoid arthritis or another form of autoimmune arthritis, medications can be prescribed to suppress the overactive immune response and relieve symptoms. Examples of these medications are immunosuppressive drugs like methotrexate or Humira (adalimumab).

Joint surgery (arthroplasty) is only used for serious joint injuries or to repair joints immobilized by arthritis. Severe cases may need a total joint replacement.

Home Remedies for Joint Effusion

While it is not a cure, you can ease joint swelling and pain at home by applying an ice pack for 15 to 20 minutes several times daily. A compression bandage can also help limit or reduce swelling. However, avoid wrapping the joint too tightly as doing so can cut off blood circulation.

Prevention

While joint effusion cannot always be avoided, there are things you can do to significantly lower your risk of it occurring:

  • Be at a weight that supports your health. Losing weight and maintaining a weight that supports your health can reduce stress on the hips and lower extremities.
  • Start a low-impact exercise plan. If you're having pain in your knee, hip, or ankle, avoid high-impact activities like heavy weightlifting or deep squats.
  • Use resistance training to strengthen joint muscles. Try using a leg extension machine for the knees or resistance band training for the shoulder and rotator cuff.
  • Stretch. Perform gentle knee and shoulder stretches before exercise or throughout the day (especially if you're sitting at a desk for long periods of time).
  • Support your joints. Use elastic knee supports or an elbow brace during contact sports, hiking, and other vigorous physical activities.
  • Don't overdo it. Be mindful not to push yourself beyond your physical capabilities, especially as you get older. You may want to consider changing the types of sports you do to protect your joints (such as switching from running to swimming or cycling).
  • Listen to your body. If you have sudden or persistent joint pain, don’t wait to see a provider for treatment. 

When to See a Healthcare Provider

Seek emergency care if you have signs of infection or injury along with the swelling. These symptoms include fever, redness around the joint, skin hot to the touch, and inability to move your joint or to put weight on it.

If you have a swollen joint without signs of an emergency, call your healthcare provider. They can have you come in for an appointment to find out what’s causing the joint swelling and make sure you get the right treatment. If they’re not sure, they might refer you to another provider who specializes in joints, like a rheumatologist or orthopedist. 

Summary

Joint effusion is extra fluid around a joint. It tends to affect larger joints, such as the knee or ankle. A joint effusion can occur as a result of injury, infection, or arthritis.

Your provider might be able to drain the excess fluid to relieve your symptoms while they work on finding out the cause or wait for treatments (like antibiotics or immunosuppressants) to start working. Making some changes to your hobbies and lifestyle can also help you manage joint effusion. 

18 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading
  • Gupta C, St. Mart J. The acute swollen knee: diagnosis and management. J Royal Soc Med. 2013; 106(7):259-68. doi:10.1177/0141076813482831

  • Marx J. Rosen's Emergency Medicine: Concepts and Clinical Practice (7th Edition). Philadelphia, Pennsylvania: Mosby/Elsevier; 2010. ISBN 978-0-323-05472-0.

Carol Eustice

By Carol Eustice
Carol Eustice is a writer covering arthritis and chronic illness, who herself has been diagnosed with both rheumatoid arthritis and osteoarthritis.