Clinical Overview
Reviewed by Joseph Maloney, MD

The point of contact between your bones, tendons and ligaments is cushioned by a small fluid-filled sac is called a bursa (plural: bursae). When a joint is overused or injured, these bursae can swell up with extra fluid, leaving less room for the tendons and bones of the shoulder to move freely. As a result, the tendons rub against the acromion (or AC) joint, causing pain, inflammation, tenderness, and swelling. If bursitis is left untreated, it can lead to pain and inflammation in the soft tissues, which may restrict the motion in that shoulder and cause pain when it is moved. Untreated bursitis may also lead to bone spurs, which will worsen the pain.

Causes and Risk Factors
Causes

• Injury
  
• Use, especially during overhead exercises
  
• Pressure on one joint for a long time
  
• Repetitive exercises, especially throwing

Risk Factors

• Strenuous activity
  
• Repetitive action