Knee bursitis - Symptoms and causes (2024)

Overview

Knee bursae

Bursae are small fluid-filled sacs, shown in blue. They lessen friction between moving parts in the body's joints. Knee bursitis is swelling, also called inflammation, of one or more of the bursae in the knee.

Knee bursitis is a condition in which one or more small fluid-filled sacs near the knee joint become inflamed. The sacs are called bursae. Bursae reduce friction and cushion pressure points between bones and tendons, muscles and skin near the joints.

Any of the bursae in the knee can be affected by painful swelling, also called inflammation. But most often, knee bursitis happens over the kneecap or on the inner side of the knee below the joint.

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Symptoms

Knee bursitis symptoms vary. They depend on which bursa is affected and what's causing the inflammation.

The affected portion of your knee might feel warm, tender and swollen. You also might feel pain when you move or when you're at rest.

A direct blow to the knee can cause symptoms to come on fast. But knee bursitis often stems from friction and irritation of the bursae. This can occur with jobs that require a lot of kneeling on hard surfaces. So, the symptoms can start slowly and become worse over time.

When to see a doctor

Sometimes, the bursa that lies over the kneecap can become infected. Call your healthcare professional if you have:

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Causes

Knee bursitis can be caused by:

Frequent and ongoing pressure, such as from kneeling, especially on hard surfaces.
Overuse of the knee or strenuous activity.
A direct blow to the knee.
An infection of the bursa due to bacteria, which could get into the knee through a bruise or a cut.
Medical problems that can happen with osteoarthritis, rheumatoid arthritis or gout in the knee.

Risk factors

Factors that can raise the risk of getting knee bursitis include:

Prolonged kneeling. The risk of bursitis is higher for people who work on their knees for long amounts of time. This includes carpet layers, plumbers and gardeners.
Playing certain sports. Sports that can lead to direct blows or frequent falls on the knee raise your risk of knee bursitis. So do sports that create friction between the knee and a mat. These sports include wrestling, football, basketball and volleyball. Runners also can get pain and inflammation in the bursa that's located on the inner side of the knee below the joint. This is called pes anserine bursitis.
Obesity and osteoarthritis. Pes anserine bursitis often occurs in obese women with osteoarthritis.

Prevention

The following tips can help you prevent bursitis or keep it from coming back:

Wear kneepads. This can help if you often work on your knees or play sports that put your knees at risk. Use padding to cushion and protect your knees.
Take breaks. If you're on your knees for a while, take regular breaks to stretch your legs and rest your knees.
Reach and stay at a healthy weight. This can help take pressure off the knee joints.

By Mayo Clinic Staff