Many people have heard of the term "bursitis", but few know what a bursa, the structure that is affected in bursitis, actually is.  In the body there are over 150 bursae (the plural of bursa).  A bursa is a small jelly-like sac, which serves as a cushion to decrease pressure between two adjacent structures.  For example, when a tendon slides against a bone in the process of moving a joint, a bursa helps to decreases the friction between these two structures. If a bursa becomes inflamed, a painful condition known as bursitis develops. Let's look at why bursitis may occur and at some of the most common types of bursitis
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What causes bursitis?  Bursitis is usually the result of an overuse or a traumatic injury. Repetitive movements, such as throwing a ball, kneeling for prolonged periods, or running, are example of activities that can produce overuse injuries. Trauma, such as a blow to an area of the body overlying a bursa, can also lead to the development of inflammation within the bursa sac.
 
Which bursae are most commonly affected?  Fortunately, only a few of the bursae in the body are likely to become inflamed. These include the bursa at the side of the hip joint (trochanteric bursa), the one on top of the shoulder (subacromial bursa), a bursa on the front of the kneecap (pre-patellar bursa) and the bursa at the tip of the elbow (olecranon bursa).

Trochanteric bursitis is a common problem that causes pain over the outside of the upper thigh. The trochanteric bursa rests between the bony prominence on the side of the upper hip (the greater trochanter) and a tendon that passes over this bone. Someone with trochanteric bursitis usually reports having hip pain at night, particularly when lying on the affected side. Pain may also be noticed at the outside of the upper hip when getting up from a chair or after prolonged walking, stair climbing, or squatting.

Subacrominal bursitis affects the shoulder, causing pain with movement such as reaching overhead or behind the back. It is part of a broader condition known as "impingement syndrome", one of the most common causes for shoulder pain. With impingement, "pinching" of the rotator cuff tendons and bursa occurs between the humerus (upper arm bone) and the bony arch (acromion) that is situated above. While it is more likely to develop in individuals over the age of 40, it is far from a geriatric problem.  Sports activities, including tennis, swimming, and baseball, can all cause subacrominal bursitis.  Work-related activities, such as overhead assembly work, can also trigger this type of bursitis.

Pre-patellar bursitis affects the bursa on the front of the knee cap (patella). This bursitis is sometimes known as "housemaid's knee", since the repetitive pressure on the front of the knee from kneeling, as when scrubbing a floor, is a typical cause. Pre-patellar bursitis can also be caused by a direct blow or fall on the knee.  In pre-patellar bursitis a fluid filled lump is often visible over the front of the kneecap.

Olecranon bursitis is associated with marked swelling at the tip of the elbow.  Prolonged pressure to the tip of the elbow, as could occur in someone who drives for long distances with their elbow on an arm rest, is an example of an activity that could produce this type of bursitis.  A traumatic injury, such as striking the tip of the elbow in a fall, can also cause olecranon bursitis.

What is the treatment for bursitis?   While there are some differences in treatment among the various types of bursitis, a few treatment principles remain the same for all types. First a period of rest is necessary. This means avoiding activities that led to the development of the bursitis or those that aggravate the problem.   Next, anti-inflammatory medications (e.g. ibuprofen, naproxen, etc.) are typically recommended to help control the inflammation. Intermittent application of ice to the skin overlying the inflamed bursa can also help to diminish inflammation as well as serving to reduce pain. Other measures that can be used in treating bursitis include physical therapy modalities, stretching exercises, cortisone injections, and rarely surgery.

A special circumstance should be mentioned when treatment of bursitis becomes urgent. If the skin overlying the bursa becomes broken, such as with an insect bite or a scrape, bacteria may get inside the bursa and cause an infection. Infected bursae can become markedly swollen with redness and swelling of the overlying skin. Surgery, to incise the bursa and drain accumulated pus, along with antibiotic treatment, is usually necessary.

So, if the doctor tells you that you have bursitis, don't feel like you are necessarily "over the hill". Bursitis is almost as common among younger, active individuals as it is in older folks.

Sources for article:
Hip bursitis from OrthoInfo
Bursitis and Tendinitis from the National Institutes of Health