Vertebral Osteomyelitis

Vertebral Osteomyelitis -- Staph. Aureus

Loss of disk space with destruction of adjacent vertebral endplates, with or without vertebral sclerosis or adjacent soft tissue masses is characteristic of vertebral osteomyelitis, especially in the appropriate clinical setting with appropriate risk factors.
Several Points are worth mentioning:

• Routes of Contamination
  • Hematogenous -- arterial or venous (Batson's plexus)
  • Contiguous Spread -- from soft tissues.
  • Direct Implantation -- trauma, iatrogenic, etc.
  • Postoperative.
• Staph. aureus most common organism implicated (80 -90%).
  • Obviously depends on patient population, etc.
  • Blood cultures sometimes positive; needle biopsy or aspiration may be required.
• Stages of hematogenous infection:
  • Typically begins as a focus of infection in anterior subchondral region of vertebral body.
  • Infection then perforates endplate to extend into intervertebral disk.
  • Subsequently invades adjacent vertebral body with loss of disk space.
  • May spread by sub-ligamentous route to form abscess masses (e.g., "cold abscess" of TB) and erode vertebral body.
• With therapy, the following can occur:
  • Radiodense vertebrae.
  • Ankylosis.
  • Osteophytosis
• Direct infection of disk is possible in children and young adults (age < 20 or 30).
• True vacuum disk phenomenon rare (R/O gas forming organism.
• Useful modalities include:
  • MRI and CT useful for definition of destruction and detection of S.T. masses.
  • Nuclear medicine bone/gallium scans useful for early detection.
  • X-rays useful to R/O other sites.

Ref:Resnick, D., Bone and Joint Imaging, W.B. Saunders, Philadelphia, PA., 1989. pp. 756-763.

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