Bursitis is a condition in which fluid-filled sacs near a joint called bursae become inflamed, causing pain and sometimes swelling. Figure 01 Bursae separate bone from overlapping muscles or tendons. Their purpose is to lubricate, cushion, and reduce friction between these tissues so that you can move your joints easily and painlessly.
Under usual conditions, the bursae are flat and contain very little fluid. When they are injured, however, they become inflamed and swell with fluid, causing pain and pressure on the surrounding tissue. Most people have about 150 bursae in their bodies.
You are most likely to experience bursitis around your shoulder, elbow, or hip joints, although the condition may also affect your knees, heels, buttocks, and even the base of your big toe. Various common names have been given to bursitis in different areas, often reflecting trades or past-times that lead to overuse of particular joints:
- Shoulder: bricklayer's shoulder or frozen shoulder
- Elbow: tennis elbow or miner's elbow
- Hip: hip bursitis or trochanteric bursitis
- Knee: housemaid's knee or clergyman's knee
- Heel: policeman's heel
- Buttocks: tailor's bottom or weaver's bottom
- Base of big toe: bunion
Bursitis can be either acute (lasting only a few days) or chronic (lasting several weeks, with many recurrences). If chronic bursitis is left untreated--especially in the shoulder--calcium deposits can form within the bursae. These deposits can lead to permanent stiffness in the affected joint.
Sometimes bacteria can invade a bursa, causing an infection. This condition is known as septic bursitis. If untreated, septic bursitis can become life-threatening, because the infection may spread through the blood to other areas of the body.
Figure 01. Bursitis of the shoulder
Overusing or injuring a joint is the most common cause of bursitis. As the common names for bursitis indicate, repeated joint movement can inflame nearby bursae. Swinging either a tennis racket or a miner’s pick, for example, can lead to bursitis of the elbow, while kneeling to work in the garden or scrub floors can result in knee bursitis. In addition, if you stand or lie on your side for long periods of time, the pressure on your hip joints may cause hip bursitis, or if you sit on a hard surface and sway back and forth (such as at a loom), you may inflame the bursa over the bone in your buttocks.
Sometimes it is difficult to identify a specific activity or injury that may have led to the bursitis. In these cases, the inflammation may be the result of gout, rheumatoid arthritis, or an infection (especially a staphylococcal infection) or, more rarely, tuberculosis. Often, however the cause of the bursitis is not identified.
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