Bursitis is the medical term for an inflammation of a bursa. A bursa is a very thin sac or a sac-like bodily cavity. A bursa usually contains synovial fluid which is a viscous fluid. The function of a bursa is to provide padding or a type of lubrication where tendons move across bones or at various points of friction between moving structures.
When healthy, a bursa creates hundreds of smooth and almost frictionless surface over which these elements slide. This is why most movements are painless.
In the event of bursitis, this smooth and frictionless surface becomes inflamed. Normally painless movement becomes rough and painful. If movement persists, the movement and friction between the surfaces actually worsens the bursitis making this a cyclical problem.
The most common site of bursitis is the shoulder. It is a very tight joint and subject to many different strains and weights. The bursa within the shoulder joint can easily damage due to this wear and tear. However, bursitis is not limited to the shoulder. All joints and areas where there is movement have bursae. Therefore, it is possible to develop bursitis all over the body.
Causes of bursitis are often caused by repetition of movement or prolonged, excessive pressure. Elbows and knees are often rested upon and this is enough to potentially cause bursitis in these joints. Other inflammatory diseases such as rheumatoid arthritis or infections also lead to bursitis. Joint swelling as a result of trauma or damage can result in bursitis as well. If the bursa swells, it needs room to expand. The space between the tendon and bone can no longer contain the bursa and further damage is caused to the joint. Bursitis, once it has taken hold of a joint, can become a self perpetuating condition causing discomfort and limited movement.