Osteomyeltitis is an infection of the bone involving the medullary cavity classified mainly by route of spread including hematogenous, direct innoculation, and contiguous spread (most common).
Radiographs are commonly obtained in the setting of soft tissue infection to evaluate for osteomyelitis.
Common soft tissue findings include:
- Soft tissue swelling
- Soft tissue gas
- Foreign body
- Ulcer
Findings of early osteomyelitis begin to appear days to weeks from time of innoculation:
- Focal osteopenia
- Periosteal reaction
- Cortical irregularity and/or thinning
- Osseous resorption and erosive change
FINDINGS:
Interval development of cortical thinning and permeative erosive change at the fifth metatarsal base, consistent with acute osteomyelitis. Erosive change extends approximately 2.5 cm distal to proximal tuberosity with regional soft tissue swelling and few locules of gas.
Early findings are often very subtle with cortical thinning and focal osteopenia prior to evolving into erosive change. Remember to compare to prior available studies.
MRI is more sensitive in early detection and in defining the extent disease.
Don’t forget to evaluate the sesamoids!