Knee bursitis: what it is, symptoms and causes of bursa inflammation

Knee bursitis is inflammation of the synovial bursa, which cushions friction between the bone and surrounding tissues. It can occur after overuse, injury or infection and usually manifests as pain, swelling and warmth in the knee area. Knowing the signs helps you understand when a doctor is needed.

What knee bursitis is

A bursa is a small fluid-filled sac. It acts as a cushion between the bone and what moves nearby: muscles, tendons, skin. Bursitis is inflammation of such a bursa, in which it becomes painful and swollen. The process can affect any joint, but it is more common in the shoulder, hip, elbow and knee. Bursitis itself usually resolves within a few weeks.

Which bursae of the knee joint become inflamed

Bursitis is inflammation of the synovial bursa, which reduces friction in the joint area. In the knee, such a bursa can also become inflamed due to overuse or infection; knee bursitis is common. By course, bursitis is divided into acute, subacute, chronic and recurrent.

Causes of knee bursitis

The first mechanism is overuse and injury. Repetitive movements, pressure on the knee, and excess weight increase the risk. Bursitis is often considered an occupational problem: it occurs in wrestlers, weightlifters, runners, as well as in people whose work requires prolonged staying in one position. The second mechanism is infection. Through a bruise, abrasion or small wound, microbes enter the bursa, most often staphylococci and streptococci. There are also internal factors: gout, arthritis, rheumatoid arthritis, diabetes mellitus, kidney disease. By the nature of inflammation, serous, purulent and hemorrhagic bursitis are distinguished.

Symptoms of knee bursitis

The typical picture: a rounded, limited swelling of soft-elastic consistency that fluctuates. The diameter may reach 8–10 cm. The following signs indicate bursitis:

• the pain is dull and aching, not sharp;
• the knee is painful on movement and on pressure;
• the skin over the bursa is warmer than the surrounding skin;
• swelling is noticeable, sometimes there is redness.

Redness is less visible on dark and tanned skin. Joint function is somewhat limited; temperature may rise, in the phlegmonous form — up to 39–40 °C.

How bursitis is diagnosed: examination, ultrasound, MRI

The diagnosis is made by an orthopedic traumatologist or surgeon, most often after examination of the joint. Then puncture is possible: fluid is taken from the bursa with a needle and sent for analysis to rule out infection and gout. Sometimes the same procedure reduces tension in the bursa. Additionally, a blood test and imaging are prescribed — ultrasound, X-ray or MRI. MRI is more informative than ultrasound and X-ray. Several methods are needed to distinguish bursitis from arthritis and deforming osteoarthritis.

Complications and when to see a doctor

If inflammation is left untreated, scar adhesions form in the joint, and mobility becomes limited. In a chronic course, fistulas are possible. Rupture of pus into the joint cavity causes purulent arthritis. A doctor should be consulted if symptoms do not resolve or worsen within 1–2 weeks. Reasons for a visit include high fever, a feeling of heat or chills, inability to move the joint, very severe sharp shooting pain. Chronic bursitis sometimes requires hospitalization. If there is no improvement within 6–12 months, surgery is discussed: the bursa is drained or removed, but this is done rarely.

Bursitis itself is not a reason to call an ambulance. The signs above are a reason to see a doctor. Call 103 or 112 in a life-threatening condition: for example, loss of consciousness, difficulty breathing, severe bleeding after injury.

The material is for reference and does not replace a doctor's consultation.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer