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  1. How are acute and chronic bone infections distinguished?

  2. What are the most frequent pathogens in osteomyelitis?

  3. Is a bone biopsy necessary to guide treatment in osteomyelitis?

  4. For how long should osteomyelitis be treated?

  5. For how long should septic arthritis be treated?

  6. Are oral antibiotics ever the appropriate treatment for osteomyelitis or septic arthritis?

  7. What is the most common bacterial cause of polyarticular arthritis?

  8. What are the indications for surgical debridement of a septic joint?



A subacute to chronic infection that can cause severe disability if improperly managed.

Osteomyelitis is a progressive infectious process that can involve one or multiple components of bone, including the periosteum, medullary cavity, and cortical bone. The disease is characterized by progressive inflammatory destruction of bone, by necrosis, and by new bone formation.


Classifying osteomyelitis is helpful because different types of osteomyelitis have differing prognoses and are treated in different ways.

Acute Versus Chronic Osteomyelitis

Acute osteomyelitis evolves over several days to weeks; chronic osteomyelitis is a disease characterized by clinical symptoms that persist for several weeks. Chronic osteomyelitis can also evolve over months or even years and is characterized by the persistence of microorganisms, by low-grade inflammation, by the presence of necrotic bone (sequestra) or foreign material (or both), and by fistulous tracts.

KEY POINTS About the Classification of Osteomyelitis

  1. Acute osteomyelitis develops over days to weeks.

  2. Chronic osteomyelitis develops over weeks to months and can persist for years.

  3. Hematogenous osteomyelitis occurs in children and elderly individuals.

  4. Infections at contiguous sites can spread to bone. Initial infections are the result of traumatic injury, penetrating injury, orthopedic surgery, or diabetic or other forms of ischemic or neuropathic ulcer.

  5. Classification into four stages based on extent of bone involvement:

    1. medullary,

    2. superficial,

    3. localized, and

    4. diffuse

Osteomyelitis of Hematogenous Origin or Attributable to a Contiguous Focus of Infection

Hematogenous osteomyelitis is the result of bacteremic spread with seeding of bacteria in bone. It is seen mostly in prepubertal children and in elderly patients. Osteomyelitis secondary to a contiguous focus of infection follows trauma, perforation, or an orthopedic procedure. As the name implies, infection first begins in an area adjacent to bone, eventually spreading to the bone. An important category of osteomyelitis resulting from contiguous spread is found in diabetic patients. Diabetic foot infection usually starts as an ulcer and commonly spreads to bone. It is secondary to neuropathy and associated with vascular insufficiency.

Classification by Extent of Bone Involvement

A second way of classifying osteomyelitis is by the extent of bone involvement. This classification guides the appropriate therapy and also predicts the eventual prognosis. Stage 1 usually can be managed with antibiotics alone, while stages 2–4 require surgical ...

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