Presentation
Limping. Not using left leg. Pyrexia.
Patient Data
Ultrasound demonstrates a large hip effusion with echogenic contents.
Focal lucency on the lateral margin of the metaphysis adjacent to the physis. The epiphysis appears normal. Features here are of osteomyelitis (and septic arthritis given the US findings).
The metaphyseal focal lucency on the plain film is demonstrated as a T2 hyperintense, T1 hypointense ring enhancing lesion with surrounding enhancing edema and a hip effusion. This confirms osteomyelitis as the most likely cause.
Case Discussion
Osteomyelitis in children favors the metaphyseal regions because they are hypervascular and consist of small vessels. The small vessels are the most likely place for relative stasis of infected blood to occur and thus, the most commonly encountered focus of bone infection.
Blood markers for infection were elevated and blood cultures positive for Strep pneumoniae.
Pain resolved following treatment with IV antibiotics.
Repeat plain film (not provided) revealed sclerosis and healing at the femoral metaphysis.