The bursa is a sac filled with lubricating fluid, located between tissues such as bone, muscle, tendons, and skin that decreases rubbing, friction, and irritation. Bursitis commonly occurs in the shoulder, elbow, hip, knee and Achilles tendon. Bursitis is caused by repetitive motion, an impact on the area, or from an injury. The most common symptom of bursitis is pain. The pain may build up gradually or be sudden and severe, especially if calcium deposits are present. Acupuncture alleviates the pain and inflammation associated with bursitis and can assist in the healing of an injury to the bursa by causing an increase in the blood flow to the region.