Knee Bursitis

What Is Knee Bursitis?

Knee bursitis is inflammation of a bursa in the knee, causing swelling, tenderness, and pain with pressure. Bursae are small fluid-filled sacs that reduce friction between the bones, tendons, muscles, and skin within joints. When the bursa becomes irritated, it fills with fluid and becomes tender to pressure. The swelling causes joint pain and may make the knee feel stiff or limit movement. 

Bursae are located in several areas around the knee, cushioning the joint. Each knee bursitis type is named for the location of the affected bursa. The most common is prepatellar bursitis — inflammation in front of the knee.

Common types of knee bursitis include:

• Prepatellar bursitis (in front of the kneecap)
• Suprapatellar bursitis (above the kneecap)
• Pes anserine bursitis (inner side of the knee)
• Infrapatellar bursitis (below the kneecap)

Knee Bursitis Symptoms and Causes

Knee bursitis symptoms vary depending on the level of inflammation and pressure on the knee.

Common symptoms of knee bursitis include:

• Localized swelling around the knee, sometimes forming a soft, fluid-filled lump
• Pain or tenderness in the affected bursa, especially with kneeling, movement, or direct pressure
• Warmth or redness in the affected area
• Fever or chills if the bursa becomes infected (septic bursitis)
• Increased sensitivity to touch or direct contact
• Stiffness in the knee
• Reduced range of motion

Signs of knee bursitis may develop quickly or gradually, depending on the cause.

Common causes of knee bursitis include:

• Frequent kneeling or prolonged pressure on the front of the knee (prepatellar bursitis)
• Direct trauma, such as a fall onto the kneecap (prepatellar bursitis)
• Repetitive motion or overuse, including running or athletic activity, particularly with obesity or osteoarthritis (pes anserine or suprapatellar bursitis)
• Infection entering through a cut, scrape, or irritation near the knee (septic bursitis, often prepatellar)
• Underlying inflammatory conditions, such as rheumatoid arthritis or gout, can affect multiple bursae around the knee)

People in occupations that involve frequent kneeling, such as plumbers, roofers, gardeners, mechanics, and flooring installers, are at higher risk for knee bursitis. Sports that involve repeated or forceful impact to the knee, such as wrestling, volleyball, rugby, football, and basketball, increase the risk for prepatellar bursitis. Running can lead to pes anserine bursitis on the inner side of the knee.

Diagnosis of Knee Bursitis

To diagnose knee bursitis, your doctor will examine your knee for swelling, tenderness, warmth, and range of motion, and ask about activities such as frequent kneeling or recent injury.

X-rays may be used to rule out other conditions, and an MRI or ultrasound may be recommended if infection or another knee condition is suspected. Aspiration of the bursa may be used to evaluate for infection or conditions such as gout.

How Long Does Knee Bursitis Last?

With rest and appropriate care, knee bursitis can improve within two to six weeks. Mild cases may resolve within a few days to two weeks, while more persistent cases or those involving infection can take weeks to several months to fully heal.

Most people recover fully without surgery. Avoiding pressure on the knee, resting the joint, and using ice or anti-inflammatory medication can help reduce swelling and speed recovery.