A bursa sac is a small, fluid-filled pouch located in various parts of the body, especially in or near joints, that acts as a cushion between moving parts of the body. The bursa sac is filled with fluid to allow flexing of the membrane, while the tougher outer layer keeps the sac intact during movement. A bursa sac can become inflamed and cause a condition known as bursitis, and this condition can occur in several joints throughout the body. The most common instances of bursitis occur in the knees and hips, though other areas of the body are susceptible as well.
Synovial fluid fills the bursa sac. This fluid is about the consistency of many cooking oils, and it allows the bursa sac to move appropriately within the joint. When the joint begins to move in ways it is not designed to, the bursa can become inflamed, leading to bursitis that causes pain, stiffness, or other discomfort in the joint. Rest is usually enough to allow the bursa to heal, though in some instances, a doctor may prescribe anti-inflammatory medications. In very serious cases, a doctor may choose to cut the bursa to alleviate pressure. The bursa will grow back after time.
When a bursa sac is functioning correctly, it will not be felt at all. If it is not functioning correctly, the area of the body in which the bursa sac is situated may swell, depending on the intensity of the inflammation. Inflammation of the bursa can occur without any external indicators such as swelling, and the pain can be just as significant. If pain is felt in a joint, it is advisable to consult a doctor to find the cause of the pain; bursitis may be the cause, but countless other conditions can cause similar pains in the joints of the body.
The location of a bursa sac can vary depending on the joint. Some bursae are located around the area where two bones come together in a joint, while others are situated between tendons, ligaments, or muscles. Bursae are often located both above and below the knee cap, as well as on the inside or outside of the knee, and these bursae are some of the most commonly inflamed in the body. Bursae are also present in the elbow, and people who do heavy lifting regularly or participate in sports that require the use of the arms are more likely to experience bursitis in the elbow.