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Key Features

Essentials of Diagnosis

  • Fever associated with pain and tenderness of involved bone

  • Diagnosis usually requires culture of bone biopsy

  • Elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)

  • Radiographs early in the course are typically negative

General Considerations

  • Occurs as a consequence of hematogenous dissemination of bacteria, invasion from a contiguous focus of infection, or skin breakdown in the setting of vascular insufficiency

  • In sickle cell anemia, Salmonella is the most common pathogen

  • In injection drug users, Staphylococcus aureus is most common, but also gram-negative (eg, Pseudomonas aeruginosa and Serratia) infections

  • Contiguous focus infections are usually due to S aureus and Staphylococcus epidermidis

Clinical Findings

Symptoms and Signs

HEMATOGENOUS OSTEOMYELITIS

  • Associated with sickle cell disease, injection drug users, diabetes mellitus, or the elderly

  • High fever, chills, and pain and tenderness of the involved bone

  • Polymicrobial infections rare

OSTEOMYELITIS FROM A CONTIGUOUS FOCUS OF INFECTION

  • Prosthetic joint replacement, pressure injury (formerly pressure ulcer), neurosurgery, and trauma are common sources of infection

  • Localized signs of inflammation are usually evident, but high fever and other signs of toxicity are usually absent

  • Septic arthritis and cellulitis can also spread to contiguous bone

  • Polymicrobial infections more common than in hematogenous osteomyelitis

OSTEOMYELITIS ASSOCIATED WITH VASCULAR INSUFFICIENCY

  • Infection originates from an ulcer or other break in the skin that may appear disarmingly unimpressive

  • Bone pain is often absent or muted by an associated neuropathy

  • Fever is also commonly absent

  • Two of the best bedside clues that the patient has osteomyelitis are

    • The ability to easily advance a sterile probe through a skin ulcer to bone

    • Presence of an ulcer area > 2 cm2

Differential Diagnosis

  • Acute hematogenous osteomyelitis should be distinguished from suppurative arthritis, rheumatic fever, and cellulitis

  • Subacute forms must be differentiated from tuberculosis or mycotic infections of bone or from bone tumors

  • When osteomyelitis involves the vertebrae, it commonly traverses the disk—a finding not observed in bone tumor

  • Cellulitis

  • Septic arthritis

  • Gout

  • Diabetic or arterial insufficiency ulcer

  • Tuberculous or mycotic bone infection

  • Rheumatic fever

  • Metastatic cancer

  • Charcot arthropathy

  • Plasma cell myeloma

  • Ewing sarcoma

  • Avascular necrosis

Diagnosis

Laboratory Tests

  • Blood cultures

  • Cultures from overlying ulcers, wounds, or fistulas are unreliable

  • ESR and serum CRP

    • Almost always elevated

    • Can be useful parameters to follow during the course of therapy

Imaging Studies

  • Early radiographic findings may include soft tissue swelling, loss of tissue planes, and periarticular demineralization of bone

  • About 2 weeks after onset of symptoms, erosion and alterations of bone appear, followed by periostitis

  • MRI, CT, and nuclear medicine bone scanning are more sensitive than conventional radiography

Diagnostic ...

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