Presentation
Metal-related worker. Penetrating injury to the left wrist by a metal particle, two months back. Presented with local pain for the last one month. On recent radiograph (5 days back) a metal opacity was visible overlying the distal dorsal radius.
Patient Data
There is an echogenic focus (about 3 mm) with reverberation artifact below the extensor carpi radialis brevis tendon. Color Doppler shows a twinkling artifact with a very high PRF.
It is about 12 - 14 mm distal to the radio-carpal joint. It is distal to the scaphoid and overlies the distal row of the carpal bones. It abuts the deeper surface of the tendon.
There is no tenosynovitis. There is no foreign body granuloma.
Intra-operative photograph showing a metal foreign body.
Case Discussion
Findings suggest a foreign body in the wrist. There are two artifacts that help to locate the foreign bodies. On grayscale, there is a reverberation artifact. On the color Doppler scan, there is a twinkling artifact.
Two possibilities should be kept in mind while looking for a foreign body.
Migration of foreign body - as in this case. Metal focus migrated from the dorsal distal aspect of radius (shown in previous radiograph - no copyright, not uploaded) to distal carpal bone level.
Fragmentation can occur if a foreign body is a wood splinter or thorn. In the case of radiolucent ( like a wood splinter ) foreign bodies, the sonographer is only aware of the approximate size of the foreign body suggested by the patient. And in such cases, fragmentation can occur revealing more than one foreign body.
Intra-operative photograph courtesy: operating surgeon Dr. Ritesh Patel
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