Peds EM Follow Up 2015: Pediatric Osteomyelitis

2 Articles of Interest & An Excruciating, Detailed and Lengthy Guide to Diagnosis and Management

 

Dartnell J, Ramachandran M, Katchburian M. Haematogenous Acute and Subacute Paediatric Osteomyelitis: A Systematic Review of the Literature. J Bone Joint Surg Br. 2012 May;94(5):584-95.

  • A meta-analysis of 1854 papers, 132 of which were examined in detail
  • 40% of patients were afebrile
  • Tibia and femur were most common sites
  • Exam, labs, and imaging must be used in combination
  • S. aureus > Kingella > other
  • Typical treatment: start empiric IV abx, switch to PO when possible

Harris JC, et al. How Useful are Laboratory Investigations in the Emergency Department Evaluation of Possible Osteomyelitis? Emerg Med Australias. 2011 Jun;23(3):317-30. Epub 2011 Apr 4

  • A meta-analysis of 36 studies of adults and children
  • Recommended algorithm:
    • Adults and kids w/ low pretest probability: nL ESR and CRP<5 → done
    • Med/high pretest probability and puncture wounds: nL ESR and CRP<5 → LOW NPV
    • ESR >30 and/or CRP>10-30 → further investigation (imaging) required
    • WBC count is not especially helpful!

Osteo locations

 

PEDIATRIC OSTEOMYELITIS:

  • Definition: bacteria infecting bone
  • Usually hematogenous spread, but can be direct inoculation (surgery, open trauma, puncture, etc) or contiguous spread (skin, sinus, dental infections)

CLINICAL PRESENTATION

  • Constitutional symptoms, irritability, decreased PO
  • +/- fever
  • Localized pain, bony tenderness
  • Functional limitations, i.e. unwilling to crawl or walk
  • Time course: usually several days to >1 week
  • Risk factors: bacteremia, sepsis, immunocompromised, indwelling catheters/hardware, prematurity, skin infection, complicated delivery, GU abnormalities

DIAGNOSIS

  • Suspected on clinical grounds
  • Likely if clinical + rad + labs (including blood cxs) are suggestive, or responds to empiric treatment
  • Unlikely if MRI or other advanced imaging are normal
  • Confirmed by micro/histo (may never happen!)

LABORATORY

  • CBC w/ Diff → leukocytosis is ~36% sensitive (true that it’s not particularly helpful, but surgery will want it)
  • ESR >20 mm/h and/or CRP >10-20 mg/L → 95% sensitive, but may need repeat q24h
  • Blood cultures x2

IMAGING

  • Plain XR
    • normally normal in Osteo, but helps r/o tumors and fractures
    • Deep tissue swelling (>3d), periosteal rxn (>10-21d), lytic sclerosis (>1mo)
      • ANY positive findings are high PPV
    • Pelvis XR: highly insensitive (~25%)
    • Vertebral osteo: 50% sensitive
    • Discitis: weeks after onset
  • MRI
    • 80-100% sensitive, 70-100% specific; high NPV
    • Better for early disease
    • Use contrast to look for abscess, otherwise non-contrast
    • If you suspect pelvic osteo, MRI is first-line
    • Bone marrow inflammation → increased signal on T2
    • Marrow and soft tissue edema
    • “Penumbra” sign: high intensity signal transition between abscess and sclerotic bone in T1
    • w/ Gadolinium: absent blood flow = ischemia, necrosis
  • CT
    • Increased bone marrow density
    • Cortex destruction
    • Periosteal reaction (new bone formed)
    • Periosteal purulence
  • ULTRASOUND
    • Fluid collection adjacent to bone w/o soft tissue inbtw
    • Periosteum elevation by >2mm, or thickening

MICRO & HISTO

  • Joint aspirate, blood, bone or periosteal scraping, percutaneous FNA
  • Blood cultures may be the ONLY positive finding!
  • Gram Positive
    • S. aureus: all ages, overlying cellulitis
    • Coag(-) Staph: neonates, indwelling catheters
    • GAS: <4yo, concomitant viral infx
    • GBS: <3mo
    • Actinomyces: facial bones, vertebrae
  • Gram Negative
    • Kingella kingae: 6-36mo, oral ulcers
    • E. coli, Serratia: <3mo, sickle cell, immunocompromised, GI procedure
    • Hib: not immunized
    • Bartonella: cats
    • Pseudomonas: IVDU
    • Brucella: unpasteurized dairy projects, endemic areas
    • TB: exposure, endemic
    • Salmonella: sickle cell disease, immunocompromised
  • Polymicrobial: more likely with puncture injuries, contiguous spread

DDX

  • Other infection (septicemia, cellulitis, septic arthritis, abscess, polymyositis) → MRI
  • Chronic Non-Bacterial Osteo → multifocal, non-responsive to abx
  • Malignancy → no response to abx, MRI, histo
  • Bone infarction in the setting of hemoglobinopathy → improvement with hydration, supportive care
  • Vit C Deficiency (Scurvy)→  bleeding gums, petechiae, ecchymosis, hyperkeratosis, coiled hair
  • Complex Regional Pain Syndrome → ESR, CRP will be normal
  • Tumors → less-than-acute onset, histo, MRI

MANAGEMENT

  • Grade 1B evidence to start empiric abx if osteomyelitis is suspected (even if XRs are negative!)
    • <3mo
      • Staph, Gram Neg, GBS
      • 3rd generation cephalosporin + anti-Staphylococcal drug (Vanc/Nafcillin/Oxacillin)
    • >3mo infants and children
      • Staph, GAS, Strep pneumo, Kingella, Hib
      • Cefazolin, Nafcillin/Oxacillin, Clinda, or Vanc
    • Adolescents
      • Staph, GAS, S.pneumo
  • Usual course
    • Improvement in 3-4 days
    • If not, consider abscess, fistula, polymicrobial infection, insufficient dosing, unusual/resistant pathogen, thromboembolism
  • Cont abx x4 weeks, or until ESR & CRP normalize….whichever is longer
  • Switch to PO when:
    • >1mo old
    • Afebrile for 48-72h
    • Normalization of white blood cell count
    • >19% decrease in ESR and 50% decrease in CRP
  • Indications for surgery:
    • Drainage of soft-tissue, subperiosteal, intramedullary purulence
    • Debridement of contiguous sources
    • Excision of devitalized bone/tissue
    • Failure to improve after 48-72h of abx

 

Much credit and thanks to Chris Merritt MD, MPH, FAAP

Image:  Peltola H, Pääkkönen M. N Engl J Med 2014;370:352-360.

Leave a Reply