Bursitis

Bursitis Overview

Bursae (one is a bursa) are fluid-filled sacs that cushion areas of friction between tendon and bone or skin. Like air-filled bubble wrap, these sacs reduce friction between moving parts of the body, such as in the shoulder, elbow, hip, knee, and heel.

The number varies, but most people have about 160 bursae throughout the body. Bursae are lined with special cells called synovial cells, which secrete a fluid rich in collagen and proteins. This synovial fluid acts as a lubricant when parts of the body move. When this fluid becomes infected by bacteria or irritated because of too much movement, the painful condition known as bursitis results.

Bursitis Causes

The most common causes of bursitis are trauma, infection, and crystal deposits.

Trauma

Trauma causes inflammatory bursitis from repetitive injury, which results in widening of the blood vessels. This allows proteins and extracellular fluid into the bursae and the bursae react against these "foreign" substances by becoming swollen.

• Chronic: The most common cause of chronic bursitis is minor trauma that may occur to the shoulder (subdeltoid) bursa from repetitive motion, for example, throwing a baseball. Another example is prepatellar bursitis (in front of the knee) from prolonged or repetitive kneeling on a hard surface to scrub a floor or lay carpet.
  
  
• Acute: A direct blow (let's say you accidentally bang your knee into a table) can cause blood to leak into the bursa. This rapid collection usually causes marked pain and swelling, most often in the knee.

Infections

Bursae close to the surface of the skin are the most likely to get infected with common organisms; this is called septic bursitis. These bursitis-causing bacteria are normally found on the skin: Staphylococcus aureus or Staphylococcus epidermis. People with diabetes or alcoholism and those undergoing steroid treatments or with certain kidney conditions, or who may have experienced trauma may be higher risks for this type of bursitis. About 85% of septic bursitis occurs in men.

Crystal deposits

People with certain diseases such as gout, rheumatoid arthritis, or scleroderma, for example, may develop bursitis from crystal deposits. Little is known about how this process happens. Uric acid is a normal byproduct of daily metabolism. People who have gout are unable to properly break down the uric acid, which crystalizes and deposits in joints-a mechanism for causing bursitis.

Bursitis Symptoms

Bursitis causes pain and tenderness around the affected bone or tendon. The bursae sacs may swell, often making movement difficult. The most commonly affected joints are the shoulder, elbow, wrist and hand, knee, and foot.

Shoulder

The subacromial (subdeltoid bursa) separates the major tendon (known as the supraspinatus tendon) from the overlying bone and deltoid muscle. Inflammation of this bursa is usually a result of injury to surrounding structures-most commonly the rotator cuff. This is often referred to as "impingement syndrome." It is often difficult to tell the difference between this type of bursitis pain and a rotator cuff injury. Both cause pain in the side or front of the shoulder.

• Overhead lifting or reaching activities are uncomfortable.
  
  
• Pain is often worse at night.
  
  
• The shoulder will usually have decreased range of active motion and be tender at specific spots.