Knee bursitis signs and symptoms vary, depending on which bursa is affected and what's causing the inflammation.

In general, the affected portion of your knee might feel warm, tender and swollen when you put pressure on it. You might also feel pain when you move or even at rest.

A sharp blow to the knee can cause symptoms to appear rapidly. But most cases of knee bursitis result from friction and irritation of the bursa that occurs in jobs that require a lot of kneeling on hard surfaces — so symptoms usually begin gradually and can worsen over time.

The bursa that lies over your kneecap

Knee bursitis can be caused by:

• Frequent and sustained pressure, such as from kneeling, especially on hard surfaces
• Overuse or strenuous activity
• A direct blow to your knee
• Bacterial infection of the bursa
• Complications from osteoarthritis, rheumatoid arthritis or gout in your knee

Knee bursitis is a common complaint, but your risk of developing this painful disorder can increase from:

• Prolonged kneeling. People who work on their knees for long periods — carpet layers, plumbers and gardeners — are at increased risk of knee bursitis.
• Participation in certain sports. Sports that result in direct blows or frequent falls on the knee — such as wrestling, football and volleyball — can increase your risk of knee bursitis. Runners can develop pain and inflammation in the pes anserine bursa, situated on the inner side of your knee below the joint.
• Obesity and osteoarthritis. Pes anserine bursitis, affecting the inner side of your knee below the joint, often occurs in obese women with osteoarthritis.