Osteomyelitis

• Classification
  • Long or vertebral
    • Long bone usually in children
      • haematogenous spread to the well vascualrised metaphyseal bone adjacent to the growth plate
    • Vertebral osteomyelitis
      • Aka discitis, spondylodiscitis
      • Usually older adults
      • Haematogenous seeding vertebral endplate
      • Secondary spinal and paraspinal collections
      • Spinal epidural abscess can exist without osteomyelititis

• Time course – acute or chronic
  • Acute – new infection, absence necrosis and sequestra, usually < 14 days
  • Chronic – relapsed or longstanding, often has a sinus, compromised soft tissue envelope, low grade inflammation, sequestra or involcurum (new bone formation adjacent to sequestra)

• Causes – adults
  • Staph aureus most common
  • Other organisms
    • Coag negative staph, strep, enterococci, Enterobacteriaceae, pseudomonas
    • More commonly atypicals if vertebral infection
    • Atypical organisms more common in patients with other risk factors
    • Post-op infection
    • Recent UTI
    • hepatobiliary or GI infection
    •  Healthcare associated infection
    • IVDU

• Causes – children
  • Almost always staph aureus
  • Rarely HiB if not fully vaccinated

• Investigations
  • Aim for microbiological diagnosis
  • Blood cultures – 50% will have bacteraemia – at least 2 sets
  • specimen – bone/pus – open or radiological biopsy
  • Start empirical treatment whilst awaiting results

• Treatment
  • Apart from non-complicated vertebral – can await results
  • Adults – long bone
    • Treat suspected staph – fluclox 2g 6hrly
    • Suspect MRSA – vancomycin
  • Adult – vertebral
    • If well/no complications/normal neuro – await culture – fluclox
    • If abscess or compromised – fluclox + vanc + ceftriaxone
  • Adult – contigous with leg or foot ulcers
    • Treat as diabetic foot infection
    • Augmentin if well
    • Piptaz if sepsis
  • Children
    • Flucloxacillin 50mg/kg 6hrly

Further follow up

• BMD before initiating corticosteroid treatment
• adequate supplementation of calcium (1200 mg/day) and vitamin D3 (cholecalciferol, 800 IU/day)
• If BMD T-score is –1.5 or less consider an oral bisphosphonate such as alendronate (70 mg/week) or risedronate sodium (35 mg/week).
• Referral to a rheumatologist should be considered if atypical features are present.