OM

Children - mostly by hematogenous spread and seeds more commonly to metaphyses

Adults -  contiguous (most often as a result of vascular insufficiency and diabetes); spread more commonly to epiphyses

Pathogens:

• Overall most common organism - Staphylococcus aureus
• those with SCD - Salmonella (NOTE! overall, most probable cause is still Staph. aureus)
• Puncture wound in adults (eg, nail stick injury through sneakers), also DM, immunocompromised pts - Pseudomonas aeruginosa
• Animal (dog or cat) bites - Pasteurella multocida
• Neonates - Group B Streptococci
• Sexually active young adults N. gonorrhoeae
• TB (Pott's disease) - Mycobacterium tuberculosis

Dx

The best initial test = X-ray (must loose >50% of Ca++ content of the bone to shows abnormality; & may take up to 2 wks) however, it is still the very first one to do

The most accurate (confirmatory) test = bone biopsy and culture

If X-ray is normal, next step is MRI (highest accuracy). If MRI is contraindicated, consider nuclear (triphasic) bone scan

MRI and bone scan are equal in sensitivity; but MRI is far more specific

The earliest fnding of osteomyelitis on an x-ray is elevation of the periosteum. Involucrum and sequestrum are terms applied to the formation of abnormal new bone in the periosteum and chunks of bone chipped off from the infection.

Evaluation of vertebral OM