Osteomyelitis

Definition

Osteomyelitis is an acute or chronic bone infection, usually caused by bacteria.

Causes, incidence, and risk factors

The infection that causes osteomyelitis often is in another part of the body and spreads to the bone via the blood. Affected bone may have been predisposed to infection because of recent trauma.

In children, the long bones are usually affected. In adults, the vertebrae and the pelvis are most commonly affected. Bone infection can be caused by bacteria or by fungus. When the bone is infected, pus is produced within the bone, which may result in an abscess. The abscess then deprives the bone of its blood supply.

Chronic osteomyelitis results when bone tissue dies as a result of the lost blood supply. Chronic infection can persist intermittently for years.

Risk factors are recent trauma, diabetes, Hemodialysis, and intravenous drug abuse. People who have had their spleen removed are also at higher risk for osteomyelitis.

The incidence of osteomyelitis is 2 in 10,000 people.

Symptoms

• Pain in the bone
  
• Local swelling, redness, and warmth
  
• Fever
  
• nausea
  
• General discomfort, uneasiness, or ill feeling (malaise)
  
• Drainage of pus through the skin (in chronic osteomyelitis)
  

Additional symptoms that may be associated with this disease:

• Excessive sweating
  
• Chills
  
• Low back pain
  
• Swelling of the ankles, feet, and legs
  

Signs and tests
A physical examination shows bone tenderness and possibly swelling and redness.

• A bone scan indicates infected bone.
  
• A CBC shows elevated white blood cell count.
  
• The ESR is elevated.
  
• Blood cultures may help identify the causative organism.
  
• An MRI and a needle aspiration of the area around infected bones for culture may be done.
  
• A bone lesion biopsy and culture may be positive for the organism.
  
• A skin lesion with a sinus tract (the lesion "tunnels" under the tissues) may yield drainage of pus for culture.