Introduction
Osteomyelitis is infection of the bone and its marrow. This topic covers the acute, subacute and chronic forms, their causes and mechanism, clinical picture, the radiological findings that matter most in the exam, specific forms (spondylodiscitis, Brodie abscess, Garré osteomyelitis, bone and joint tuberculosis), differential diagnosis, treatment and complications. Radiology is central here, because the plain-film appearances change with the stage of disease and are often confused with tumours.
Definition and classification
Osteomyelitis is inflammation of bone caused by infection, usually bacterial (about 80% S. aureus), that spreads through the cortex, medulla and periosteum. It is classified in three ways:
- By duration: acute, subacute, chronic. The main distinction is between acute osteomyelitis, which lasts days to weeks, and chronic osteomyelitis, which persists for months or years (more than a month) and produces dead bone and new bone formation.
- By spread of infection: haematogenous; extension from adjacent soft-tissue infection; direct inoculation (open fracture, puncture wounds, surgical intervention).
- By purulent production: pyogenic (S. aureus) and non-pyogenic (other pathogens).