CIM Case: Chronic Osteomyelitis in Child

Clinical Scenario

Patient: 12-year-old girl Presentation: 3 months post closed reduction of proximal humerus fracture treated with hanging cast, ongoing pain and now developing intermittent discharge from anterior shoulder Relevant history: Initially uncomplicated fracture from netball injury, treated in ED with closed reduction and hanging cast for 6 weeks, slow to recover with persistent dull ache, low-grade fevers (37.8°C) noted at home, no antibiotic treatment previously Examination findings:

• Sinus tract over anterolateral proximal humerus with purulent discharge
• Surrounding erythema and induration
• Reduced range of motion (elevation 90°, external rotation 20°)
• No acute systemic sepsis
• Afebrile currently
• Axillary lymphadenopathy
• Otherwise well, no weight loss

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Investigations Provided

Laboratory Results

Imaging

Image 1: AP and Lateral Radiographs of Right Humerus

Radiological features:

• Fracture healed in acceptable alignment
• Periosteal reaction with cortical irregularity around proximal metaphysis
• Central area of lucency with sclerotic rim (Brodie's abscess/sequestrum)
• New bone formation laterally (involucrum)
• Cloaca visible (draining tract through cortex)
• No pathological features of tumour

Image 2: MRI of Right Proximal Humerus

MRI findings:

• 3cm intramedullary abscess in proximal humeral metaphysis
• Cortical breach with soft tissue extension
• Surrounding bone oedema on STIR sequences
• Sinus tract extending to skin surface
• No joint involvement
• Physis appears intact

Questions & Model Answers

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Key Teaching Points

Pattern Recognition

This pattern suggests Chronic Osteomyelitis:

• Prior bone insult (fracture, surgery, haematogenous)
• Prolonged symptoms >6 weeks
• Draining sinus tract
• Low-grade systemic features (mild anaemia, raised ESR/CRP)
• Imaging showing sequestrum, involucrum, cortical irregularity

Distinguish from Acute Osteomyelitis:

Critical Management Points

1. Deep tissue culture is essential - never treat on swab alone
2. Debride to paprika sign - all remaining bone must bleed
3. Rifampicin for biofilm - but never as monotherapy
4. Manage dead space - beads, cement, or flap
5. Prolonged antibiotics - 6-12 weeks minimum
6. CRP tracks response - ESR slower to change
7. Second-look if needed - don't hesitate to re-debride

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Common Examiner Follow-ups

Q: "What is the role of hyperbaric oxygen therapy?"

Hyperbaric oxygen therapy (HBOT):

• Adjunctive therapy for refractory chronic osteomyelitis
• Increases tissue oxygen tension
• Enhances neutrophil bacterial killing
• Promotes angiogenesis in ischaemic tissue
• Potentiates some antibiotics
• Evidence mixed but may be considered for:
  • Refractory cases after multiple debridements
  • Compromised hosts (diabetes, vascular disease)
  • Extensive involvement
• Not first-line treatment

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Q: "How would you manage a growth disturbance from physeal involvement?"

If physis is involved and damaged:

• Monitor for growth arrest with serial X-rays
• Compare limb lengths clinically and radiographically
• If bar forms: Consider bar excision if <50% physis and 2+ years growth remaining
• If significant LLD predicted: Contralateral epiphysiodesis or limb lengthening
• For this patient: Physis appears intact on MRI - monitor but low risk

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Q: "What if this patient had a pathological fracture through the infected bone?"

Management of pathological fracture through osteomyelitis:

• Priority: Treat infection AND stabilise bone
• Debridement as usual
• Stabilisation options:
  • External fixation (preferred - keeps hardware outside infection)
  • Plate fixation with antibiotic cement coating
  • Antibiotic-coated intramedullary nail (newer)
• Bone grafting after infection controlled (staged)
• Avoid standard internal fixation without addressing infection
• May need longer antibiotics and multiple stages

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Q: "What is the role of PET-CT in osteomyelitis?"

FDG PET-CT role:

• Differentiates infection from tumour (both can be hot)
• Detects extent of infection not seen on MRI
• Useful when MRI contraindicated (metalwork, pacemaker)
• Can detect multifocal disease
• Monitors treatment response
• Limitations: radiation exposure, availability, cost, less anatomical detail than MRI

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Related Topics

• Acute Paediatric Osteomyelitis
• Brodie's Abscess
• Septic Arthritis
• Prosthetic Joint Infection
• Antibiotic Bone Penetration
• Negative Pressure Wound Therapy