A swollen knee is a common and frustrating symptom of conditions caused by a fluid buildup in or around the knee joint, which may cause discomfort, limit mobility, and interfere with daily activities. While swelling can develop after an injury or overuse, persistent or recurring knee swelling and pain may signal osteoarthritis or another underlying condition.  

Understanding what causes knee swelling can help you determine whether at-home care is enough or whether you should see a specialist for evaluation and treatment.

What Causes Knee Swelling?

Knee swelling can have many causes, from temporary injuries to chronic joint conditions. It can range from mild and short-lived to severe and persistent, depending on the underlying condition.

Knee Osteoarthritis

Osteoarthritis is a degenerative joint disease that gradually wears away the cartilage, the smooth, cushioning tissue that protects your joints. As cartilage deteriorates, increased friction and inflammation within the joint can lead to swelling and pain on or around the knee.

Other common osteoarthritis symptoms include: 

• Stiffness 
• Tenderness 
• Reduced mobility 
• Pain that worsens with weight-bearing activities

Symptoms can fluctuate, with a swollen knee appearing after increased activity and improving with rest. 

Knee Injuries and Overuse

Injuries can trigger inflammation or bleeding within the knee, resulting in fluid buildup. Common injuries that can cause knee swelling include ACL tears, meniscus tears, fractures, and irritation from repetitive movements.

An ACL injury may cause sudden pain, instability, and rapid swelling, sometimes following a popping sensation. A torn meniscus can also cause knee swelling and pain, along with stiffness, catching, locking, or difficulty fully straightening the leg.

Other Medical Conditions That Can Cause Knee Swelling

Not every swollen knee is caused by osteoarthritis or an injury. Other potential reasons a knee swells up include:

• Rheumatoid arthritis
• Gout
• Pseudogout
• Bursitis
• Infection
• Cysts
• Tumors

Since treatment depends on the cause, consult a medical professional, such as a knee specialist, for persistent or unexplained swelling.

Where Knee Swelling Occurs and What It May Mean

The location of swelling can provide clues about what is happening inside or around the joint.

Swelling Behind the Knee

Swelling behind the knee is typically associated with a Baker’s cyst, or popliteal cyst. This fluid-filled sac develops when knee inflammation causes excess joint fluid to collect behind it.

Baker’s cysts often develop as a result of underlying knee conditions such as osteoarthritis, rheumatoid arthritis, or meniscus tear. Treatment is typically directed at the underlying condition rather than the cyst itself.

A ruptured Baker’s cyst should be evaluated promptly because it can cause sudden calf pain, redness, and swelling that may mimic a blood clot.

Swelling on the Outside of the Knee

Swelling on the outside of the knee can occur with iliotibial band syndrome, lateral collateral ligament injuries, meniscus tears, ACL injuries, and osteoarthritis. 

Depending on the cause, outer knee symptoms can include: 

• Aching or sharp pain 
• Stiffness 
• Instability 
• Clicking 
• Locking 
• Difficulty bending and straightening the leg 

When Should I Worry About Knee Swelling?

Mild activity-related swelling may improve with at-home care. However, medical evaluation is recommended for severe swelling, especially if it: 

• Keeps returning 
• Limits your mobility 
• Does not improve with rest or other self-care 

Seek prompt medical attention if the knee becomes unusually warm or changes color, alongside a fever or feeling unwell. These signs may indicate an infection or another condition requiring immediate care. 

How Is Knee Swelling Diagnosed?

A knee pain specialist can diagnose knee swelling and determine its underlying cause during an initial consultation. During this consultation, a healthcare professional may start with a medical history and physical exam to assess pain, mobility, past injuries, and other symptoms. 

Imaging tests may also be recommended, including:

• X-rays: Provide a clear picture of your bones, helping to identify bone spurs or signs of cartilage damage.
• Ultrasound: Identifies fluid buildup and inflammation in the soft tissues around your knee joint.
• MRI: Provides a detailed image of the knee’s cartilage, ligaments, and tendons to help identify osteoarthritis or other underlying conditions.

In some cases, doctors may collect joint fluid and analyze it for signs of infection, gout, or inflammatory arthritis when evaluating the cause of knee swelling.H2: How Does Osteoarthritis Cause Knee Swelling?

Osteoarthritis can cause knee swelling when changes within the joint lead to inflammation and excess fluid buildup. As the cartilage cushioning the knee deteriorates, increased stress and friction within the joint can contribute to inflammation, causing swelling and pain in the knee.

Knee swelling from osteoarthritis may become more noticeable after walking, standing for long periods, or other weight-bearing activities. For some people, swelling may come and go depending on activity levels and inflammation within the joint.

How to Treat Knee Swelling Caused by Knee Arthritis

When it comes to treatment for swelling in the knee joint, the best approach depends on its cause and severity. Mild swelling may improve with at-home measures, while persistent or recurring swelling may require medical evaluation and treatment:

• Rest: Not placing stress on a swollen knee and icing it can help with mild cases.
• Medications: Nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids can help reduce inflammation and swelling.
• Physical Therapy: Strengthening exercises help stabilize the joint and improve mobility.
• Compression and Elevation: A knee brace or elevating the leg can help reduce swelling.

Treating an underlying condition such as arthritis may also help control swelling. For persistent osteoarthritis-related knee symptoms, you may consider additional treatment, such as genicular artery embolization (GAE). 

Treating Knee Swelling with GAE

Certain patients with knee osteoarthritis may benefit from GAE to manage symptoms without major surgery.  Genicular artery embolization is a minimally invasive procedure that targets the small blood vessels associated with chronic knee inflammation.  GAE reduces blood flow to the inflamed areas of the knee, relieving swelling, pain, and stiffness.

GAE may be a highly effective option for patients seeking to avoid or delay knee replacement surgery by offering:

• No major surgery 
• Significant symptom improvement
• Preservation of the knee joint
• Fast recovery

Find Relief for Knee Pain and Swelling at USA Pain Center

If knee swelling from an underlying condition like osteoarthritis is holding you back, advanced treatments like genicular artery embolization (GAE) can provide the relief you need. USA Pain Center specializes in innovative, minimally invasive solutions to help you live with less knee pain and discomfort. 

Schedule a consultation with a knee pain specialist to learn if  GAE is right for you.

Schedule Online Today

FAQs

Is walking good for a swollen knee?

Walking may aggravate a swollen knee if the joint is inflamed or injured. Resting the knee and avoiding activities that worsen symptoms may help with short-term swelling, but a medical professional should evaluate ongoing or unexplained swelling.

Should you use heat or ice for knee swelling?

Ice is generally recommended for swelling, particularly following an acute injury. Heat may help with stiffness associated with some chronic conditions, but it may not be appropriate when the knee is actively swollen.

Why does my knee keep swelling up without an injury?

When a knee swells up without an obvious injury, osteoarthritis or inflammatory arthritis may be responsible. Other possibilities include gout, bursitis, infection, and tendinitis.

Can knee swelling come and go?

Knee swelling may come and go with osteoarthritis and other inflammatory conditions, becoming more noticeable after increased activity and improving with rest.

Does losing weight help reduce knee swelling?

Losing weight can help reduce knee swelling because it places less stress on weight-bearing joints, such as the knees. Maintaining a healthy weight can help protect and manage overall joint health.

Can Knee Swelling Be Cured?

Treatment depends on the underlying cause. Some cases of knee swelling improve completely after an injury heals, while chronic conditions such as osteoarthritis may require ongoing management to control inflammation and symptoms.

USA Pain Center offers genicular artery embolization (GAE), a less invasive alternative to knee surgery. GAE is performed by an interventional radiologist using image guidance to precisely reach the genicular arteries associated with knee inflammation. The doctor guides a thin catheter to the treatment area and delivers tiny particles that target the small blood vessels associated with chronic inflammation in the knee.

 

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