Digital osteomyelitis

Case contributed by Dr Elnasif Ahmad

Presentation

Diabetic patient with history of bee-sting to the right middle finger which was incised, drained and treated with antibiotics at the time of plain film. MRI was obtained 2 months later.

Patient Data

Age: 56
Gender: Male
Modality: X-ray

There is marked soft-tissue swelling of the right middle finger. Loss of density and cortical definition at the tip of the 3rd distal phalanx is noted, consistent with osseous erosion.

Modality: MRI

Edema of the bone marrow and surrounding soft-tissue and cortical disruption of the distal phalanx are more conspicuous on the fat saturated sequence. The post-gadolinium sequence from this study was not included because it was not fat-saturated, but did show surrounding soft-tissue enhancement.

Case Discussion

The earliest features of osteomyelitis are seen on MRI, manifesting as bone marrow edema, which can be seen in as little as 24-48 hours from the onset of infection. This is at a time where the only plain film findings would be surrounding soft-tissue swelling. Even nuclear medicine bone scans take a few days before showing increased uptake. Later on as time progresses, sclerosis and/or lucency and periosteal reaction may be evident on plain films, at which time MR demonstrates more well-defined edema, bone abscesses (Brodie abscess) with peripheral contrast enhancement, and similar findings in the soft-tissues. The hallmarks of chronicity are bony sequestra (dead bone) within an involucrum (essentially a cavity), cloaca (cortical break in involucrum allowing for decompression into the soft-tissues), and sinus tracts. A sequestrum may be seen on plain films, CT, and MRI.

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Case Information

rID: 32566
Case created: 3rd Dec 2014
Last edited: 16th Sep 2015
Inclusion in quiz mode: Included

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