Osteomyelitis

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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.

This disease may alter the results of the following tests:

• Joint X-ray
  
• Hand x-ray
  
• Extremity x-ray
  
• Bone x-ray
  
• ALP (alkaline phosphatase) isoenzyme
  
• ALP

Treatment
The objective of treatment is to eliminate the infection and prevent the development of chronic infection.

Intravenous antibiotics are started early and may later be changed depending on culture results. Some new antibiotics can be very effective when given orally.

In chronic infection, surgical removal of dead bone tissue is usually necessary. The open space left by the removed bone tissue may be filled with bone graft or by packing material to promote the growth of new bone tissue. Antibiotic therapy is continued for at least 3 weeks after surgery.

Infection of an orthopedic prosthesis may require surgical removal of the prosthesis and of the infected tissue surrounding the area. A new prosthesis may be implanted in the same operation or delayed until the infection has resolved, depending on its severity.

Expectations (prognosis)

The outcome is usually good with adequate treatment of acute osteomyelitis.

The prognosis is worse for chronic osteomyelitis, even with surgery. Resistant or extensive chronic osteomyelitis may result in amputation, especially in diabetics or other patients with poor blood circulation.

Complications

• Chronic osteomyelitis
  
• Local spread of infection
  
• Reduced limb or joint function
  
• Amputation

Calling your health care provider
Call your health care provider if you have symptoms of osteomyelitis, or if you have osteomyelitis and the symptoms persist despite treatment.

Prevention
Prompt and complete treatment of infections is helpful. High-risk people should see a health care provider promptly if they have signs of an infection anywhere in the body.

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