Management of Metal Foreign Bodies in Soft Tissue

Diagnostic Approach

Radiographs of the area of interest are the appropriate first imaging study for suspected metal foreign bodies, with multiple views to maximize detection of these radiopaque objects 2, 3, 4, 5
Metal foreign bodies are radiodense and can be detected on radiographs, unlike plastic, rubber, and wood which are radiolucent 4, 5
If radiographs are negative but a foreign body is still suspected, ultrasound (US) is the preferred imaging modality with a reported sensitivity of 95% for foreign body detection 3, 6
CT without IV contrast is an equivalent alternative to US, with 5-15 times higher sensitivity than radiography for detecting foreign bodies 6, 5
CT can precisely localize foreign bodies and identify their composition based on attenuation and Hounsfield unit values 6
MRI should be avoided initially for metallic foreign bodies due to potential risks from the magnetic field and should only be used after radiographic screening confirms safety 3, 7

US can characterize foreign body morphology, depth, and relationship to adjacent structures, and provide real-time guidance during removal 6, 1
Surgical exploration is necessary when the foreign body is adjacent to critical structures or embedded in bone 1
Hand surgeons or appropriate specialists should be consulted due to the risk of damage to tendons, nerves, and blood vessels during removal 1

Potential complications include tendon or nerve injury from the foreign body or during removal, and chronic inflammation and infection 1
Follow-up imaging may be necessary to confirm complete removal, especially if multiple foreign bodies were present 6

For metal foreign bodies in the hand, special attention must be paid to the complex anatomy and potential for functional impairment 1
MRI is contraindicated before confirming the absence of ferromagnetic properties due to potential for severe soft tissue heating and motion of the foreign body 3, 7
The depth of the foreign body influences the choice of removal technique, with objects deeper than 4cm from the skin being more difficult to detect and remove with ultrasound 7