Bursitis

3 things to know first

1. It is not an infection of the joint. Bursitis is inflammation of a small cushioning sac near a joint, tendon, or bone.
2. It is usually caused by repetitive use or pressure. Activities, kneeling, or leaning on an elbow can trigger it.
3. Most cases improve with simple care. Rest, ice, and avoiding the aggravating activity often lead to recovery.

What it is

Bursae are small, thin sacs filled with a small amount of fluid. They act as cushions between bones, tendons, muscles, and skin near joints. There are more than 150 bursae in the human body.

Bursitis happens when a bursa becomes irritated or inflamed. Common locations include the shoulder (subacromial bursitis), elbow (olecranon bursitis), hip (trochanteric bursitis), knee (prepatellar or pes anserine bursitis), and heel. In most cases, bursitis is not infectious. A small number of cases can be caused by infection, especially after a cut or puncture near the bursa.

Why it appears on your report

On MRI or ultrasound, an inflamed bursa may look larger than normal or contain extra fluid. The radiologist reports this as bursitis to explain the source of pain or swelling near a joint. The finding is often seen alongside tendinopathy or arthritis.

How serious is it

Bursitis is usually a localized, self-limited problem. It can be painful and limit movement, but it is rarely serious. Severity depends on:

• Cause: Overuse or pressure-related bursitis usually improves with rest. Infected bursitis needs prompt antibiotic treatment.
• Location: Some areas, such as the hip or shoulder, can significantly affect daily activities.
• Duration: Acute bursitis often settles in days to weeks. Chronic bursitis can last longer and may recur.

When to seek care urgently

Seek urgent care if you have:

• A hot, very red, and swollen joint with fever
• Severe pain that does not allow any movement
• A wound or puncture near the swollen area
• Signs of spreading infection such as red streaks on the skin

These may suggest septic bursitis, which needs prompt treatment.

What usually happens next

1. Activity modification. Avoid or reduce the movement or pressure that triggered the bursitis.
2. Self-care. Ice, rest, and over-the-counter pain relief can help, if appropriate for you.
3. Physical therapy. Strengthening and stretching nearby muscles may reduce recurrence.
4. Medical treatment if needed. Persistent cases may benefit from a corticosteroid injection or, rarely, drainage. Antibiotics are used if infection is present.

A simple analogy

Think of a bursa as a tiny water balloon that sits between moving parts. Bursitis is like the balloon getting swollen and sore from too much rubbing or pressure. Once the rubbing stops and the swelling goes down, the joint usually feels better.

Further reading

• Mayo Clinic — Bursitis
• NHS — Bursitis