Bursitis is a common sports-related injury and can also be an occupational hazard if a person's job requires repetitive motions over extended periods. A bursa is a fluid-filled sac inside the joint. It lies between a joint bone and the muscle or tendon that covers it, and serves as padding or a shock-absorber, protecting the soft tissue from damage due to friction against the hard bone. In vigorous or repetitive movement, the friction of the bone on the bursa can cause inflammation of the sac, leading to pain and swelling. This condition is called bursitis and can occur in any joint. Shoulders, knees and elbows are the most common sites of this condition.
Common bursitis is caused by overuse of the muscle covering the bursa, but infectious bursitis is a condition in which the bursa itself becomes infected. If the pain is accompanied by fever or swollen glands, it may be an infection. Such cases should be treated by a medical professional, usually with antibiotics if it's caused by bacteria. Some cases may require that the infected bursa be drained.
Bursitis takes up to six weeks to heal completely, although major pain symptoms will often, with treatment, clear up within three weeks. Resting the effected joint is critical, since further exertion can cause more damage that might take longer to heal or require more invasive treatments. Icing the effected joint will both reduce the swelling and dull the pain, but will also lessen circulation to the joint. Topical skin creams that contain menthol can reduce the pain and increase circulation to the area, and are often preferable to ice in this situation.
Common cases are treated with anti-inflammatories and sometimes with a shot of cortisone directly in the joint. Long-term use of cortisone can damage cartilage and deplete the bones of minerals, so this treatment is used sparingly. People can reduce their chances of bursitis by stretching joints that are prone to the condition; this lengthens the muscle and tendons and gives them more "slack," making it less likely that the bursa will be irritated by friction against the bone.