Bursitis

What a bursa is

A bursa is a tiny pocket of synovial fluid (the same slippery substance that lubricates joints) located at friction points in the body. Its job is to reduce rubbing and pressure when a tendon or muscle slides past bone. Think of it as nature’s shock absorber, strategically placed wherever two moving structures come into close contact.

The body has dozens of bursae. Most you’ll never hear about because they quietly do their job for life. But when one becomes irritated and swells with excess fluid, it becomes painful. That’s bursitis.

Where bursitis happens

• Trochanteric bursa (hip). On the outside of the hip, over the bony prominence (trochanter). A common site in runners and people who sleep on their side. Causes pain on the outside of the hip, especially going up stairs or lying on that side.
• Subacromial bursa (shoulder). Under the acromion bone at the top of the shoulder. Irritated when the rotator cuff is pinched or strained. Causes pain with overhead activities and at night.
• Olecranon bursa (elbow). Over the pointy back of the elbow. Can swell noticeably and become visible as a fluid-filled bump. Often from repeated leaning on the elbow.
• Prepatellar and infrapatellar bursae (knee). At the front of the knee, above and below the kneecap. The prepatellar bursa is what kneels on the ground; prolonged kneeling irritates it (sometimes called “housemaid’s knee”).
• Retrocalcaneal bursa (heel). Behind the Achilles tendon insertion. Irritated by tight calf muscles or stiff shoes pressing on the back of the heel.

How bursitis develops

Bursitis usually starts with repetitive pressure or friction on that spot. A runner logging more miles than usual stresses the hip; the subacromial bursa under the shoulder compresses in someone doing overhead reaching; a worker kneeling on a hard floor irritates the prepatellar bursa. The bursa responds to irritation by producing more fluid, swelling, and becoming more inflamed.

Sometimes an infection causes bursitis, but most orthopedic bursitis is non-infectious — it’s a mechanical problem. The bursa is being pinched, compressed, or overworked, and it’s swelling as an inflammatory response. Unlike a joint, a bursa doesn’t move. Once it’s inflamed, it stays inflamed until you address the cause.

Why it responds well to treatment

Bursitis is one of the more treatable orthopedic problems. Because the bursa is a purely inflammatory condition (not a structural failure like a tendon tear), NSAIDs and corticosteroid injections work well. Rest removes the irritating pressure. Activity modification (changing the movement or position that caused it) prevents recurrence.

If the irritation was mild, a week of NSAIDs and rest may be enough. If the bursa is notably swollen or painful, a corticosteroid injection placed directly into the bursa can dramatically improve symptoms in days.

Treatment approach

• Rest and activity modification. Stop the activity causing repetitive irritation. This is the foundation. If kneeling caused it, kneel less or use a cushion. If running caused hip bursitis, reduce miles temporarily.
• Ice and elevation. For the first 48 hours, ice reduces swelling and pain.
• NSAIDs. Ibuprofen or naproxen taken for a few days to a week calms the inflammatory response.
• Corticosteroid injection. If symptoms don’t improve within a week or two, or if the swelling is large, an injection can be curative. Ultrasound guidance ensures the needle reaches the exact bursa.
• Physical therapy. If the bursitis was triggered by muscle tightness or weakness (tight hip flexors causing hip bursitis, weak rotator cuff causing shoulder bursitis), therapy addresses the root cause so it doesn’t recur.

Recovery timeline

Non-infected bursitis often resolves within 2–4 weeks of rest and NSAIDs. If an injection is given, improvement is faster — often days. The key is removing the irritant and not returning to the same pattern that caused it. A runner can usually return to running once pain-free, but may need to build miles gradually or address the biomechanical issue that triggered the bursa to inflame in the first place.

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