Bursitis is commonly caused by:

• Overuse and repeated movements. These can include daily activities such as using tools, gardening, cooking, cleaning, and typing at a keyboard.
• Long periods of pressure on an area. For example, carpet layers, roofers, or gardeners who work on their knees all day can develop bursitis over the kneecap.
• Aging, which can cause the bursa to break down over time.
• Sudden injury, such as a blow to the elbow.

Bursitis can also be caused by other problems, such as arthritis or infection (septic bursitis).