Saturday, June 21, 2008

Radiographic appearance in Osteomyelitis

    • Periosteal reaction
      • Thin, linear periosteal reaction
      • Thick periosteal reaction
      • Laminated—"onion peel"
      • Codman's triangle—periosteum forms bone only at the margins of the periosteal triangle
    • Bone destruction
      • Permeating bone lesion
      • Punched-out bone
      • Moth-eaten
      • Geographic
      • Aggressive osteolysis
      • Well-defined osteolytic lesion with thick sclerotic border
    • Localized cortical thickening
    • Involucrum
      • Reactive new bone surrounding sequestrum
    • Ground-glass
    • Diffusely dense bones
  • CT—for evaluation of
    • Chronic disease
    • Soft tissue expansion
    • Sequestra
    • Sinus tracts
  • MR—relative to X-ray
    • Increased sensitivity
    • Decreased specificity
  • Nuclear Medicine
    • Tc99m-MDP bone scan
      • More sensitive than plain film
      • Negative rules out osteomyelitis
      • Phases (osteomyelitis positive through all 3 phases, cellulitis is negative on delayed)
        • Flow
        • Blood pool
        • Delayed
    • If underlying bone abnormal (i.e. diabetic foot, fractures, nonunion, pseudoarthroses, hardware) use multiple isotope scintigraphy (Tc99m-MDP combined with the agents listed below)
      • Sulfur colloid
        • Defines extent of red marrow
      • Labeled WBC's (Indium-111 or Tc99m-HMPAO)
        • Infection suggested by
          • Activity in absence of sulfur colloid activity
          • Greater activity than that of sulfur colloid
        • If activity of labeled WBC's and sulfur colloid ~equal, probably just marrow not infection
      • Gallium
        • Used in place of labeled WBCs
        • Less effective
  • Risk factors
    • Penetrating trauma
    • Immunocompromised
    • IV drug abuse
    • Diabetes mellitus
    • Sickle cell disease
  • Sequestrum and/or abscess
    • Antibiotics and surgical drainage
  • In patients <>

References:

  1. Weissleder et al, Primer of Diagnostic Imaging, 4th edition, 2007.
  2. Bookstein, Medical Student's Pocket Reference, 4th edition, 2002.
  3. Brant & Helms, Fundamentals of Diagnostic Radiology, 3rd edition, 2006.
  4. STATdx, url: my.statdx.com (by Amirsys, Inc.).

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