Osteomyelitis describes an infection of the bone. It may be subclassified into:

• haematogenous osteomyelitis
  • results from bacteraemia
  • is usually monomicrobial
  • most common form in children - staph aeurus is the most common causative organism
  • vertebral osteomyelitis is the most common form of haematogenous osteomyelitis in adults
  • risk factors include: sickle cell anaemia, intravenous drug user, immunosuppression due to either medication or HIV, infective endocarditis
• non-haematogenous osteomyelitis:
  • results from the contiguous spread of infection from adjacent soft tissues to the bone or from direct injury/trauma to bone
  • is often polymicrobial
  • most common form in adults
  • risk factors include: diabetic foot ulcers/pressure sores, diabetes mellitus, peripheral arterial disease

PC

Children with bone infection usually present with severe pain, high temperature and clinically there will be tenderness over the metaphysis of the bone. Joint movements generally are not affected.

Investigations

Labs:

• FBC
• inflammatory markers
• blood cultures

Imaging:

• X-ray - may be negative early on as periosteal reaction cannot be seen until about 7 days and bone necrosis after 10 days. It is useful in the diagnosis of chronic osteomyelitis.
  • findings: osteopenia, periosteal thickening, focal bone loss, endosteal scalloping, loss of trabecular bone architecture, eventual peripheral sclerosis
• CT - good for identifying necrotic bone and for guiding needle for biopsy.
• MRI is the imaging modality of choice, with a sensitivity of 90-100%

Special tests:

• Bone biopsy is required for definitive diagnosis (pathology and culture)
  • Staph. aureus is the most common cause except in patients with sickle-cell anaemia where Salmonella species predominate