• Acute osteomyelitis usually occurs in children
• Usually a haematogenous infection from distant focus
• Organisms responsible include:
  • Staph. aureus
  • Strep. pyogenes
  • H. influenzae
  • Gram-negative organisms
• Salmonella infections are often seen in those with sickle-cell anaemia
• Infection usually occurs in metaphysis of long bones

Pathology

• Acute inflammation results in raised intraosseous pressure and intravascular thrombosis
• Suppuration produces a subperiosteal abscess that may discharge into soft tissues
• Spread of infection into epiphysis can result in joint infection
• Within days bone death can occur
• Fragments of dead bone become separated in medullary canal (sequestrum)
• New bone forms below stripped periosteum (involucrum)
• If infection rapidly controlled resolution can occur
• If infection poorly controlled chronic osteomyelitis can develop

Clinical features

• Child usually presents with pain, malaise and fever
• Often unable to weight bear
• Early signs of inflammation are often few
• Bone is often exquisitely tender with reduced joint movement
• Late infection presents with soft-tissue swellings or discharging sinus
• Diagnosis can be confirmed by aspiration of pus from abscess or metaphysis
• 50% of patients have positive blood cultures

Radiology

• X-rays can be normal during first 3 to 5 days
• In the second week radiological signs include:
  • Periosteal new bone formation
  • Patchy rarefaction of metaphysis
  • Metaphyseal bone destruction
• In cases of diagnostic doubt bone scanning can be helpful

Differential diagnosis

• Cellulitis
• Acute suppurative arthritis
• Rheumatic fever
• Sickle-cell crisis

Management

• General supportive measures should include intravenous fluids and analgesia
• Painful limb often requires a splint of skin traction to relieve symptoms
• Aggressive antibiotic therapy should be instituted
• Flucloxacillin is often the antibiotic of choice
• If fails to respond to conservative treatment surgery may be required
• A subperiosteal abscess should be drained
• Drilling of metaphysis is occasionally required
• Overall, about 50% of children require surgery

Complications

• Metastatic infection can occurs at distant sites (e.g. brain, lung)
• Spread into joint can result in a septic arthritis
• This complication occurs in:
  • Young children in whom the growth plate is permeable
  • Bones in which the metaphysis is intracapsular
  • Epiphysis of bones involved in metastatic infection
• Involvement of physis can result in altered bone growth
• Failure to eradicate infection can result in chronic osteomyelitis

Bibliography

Lew D P,  Waldvogel F A.  Osteomyelitis.  Lancet 2004;  364:  369-379.

Ray P S,  Simonis R B.  Management of acute and chronic osteomyelitis.  Hosp Med 2002;  63:  401-407.

Parsons B,  Strauss E.  Surgical management of chronic osteomyelitis.  Am J Surg 2004;  188 (Suppl 1):  57-66