Effectiveness of magnets in removing metallic foreign bodies

Metallic foreign bodies (MFB) in the extremities are a common clinical problem that requires removal to prevent complications and to avoid contraindications to magnetic resonance imaging. While magnetic extraction represents an alternative to conventional surgical techniques, systematic data regarding its efficacy and clinical utility remain limited. This study aimed to evaluate the clinical efficacy of magnetic extraction for MFBs in extremities, its impact on radiation exposure, and success rates across different anatomical locations and foreign body types.

We retrospectively reviewed data on patients who underwent MFB removal surgery between 2017 and 2025 at a tertiary trauma center. Of the 364 patients reviewed, 51 met the inclusion criteria after excluding non-metallic foreign bodies, cases in which magnets were not used, and incomplete records. Demographic data, anatomical location, foreign body characteristics, use of image intensifier, and magnet efficiency were recorded.

A magnet was used for 52 MFBs in 51 patients. Magnetic extraction of MFBs was successful in 87% (45/52) of cases. The success rate was 100% for metal splinters but decreased to 63% for the needle-type foreign bodies (p < 0.001). Magnetic extraction succeeded in all upper-extremity cases (28/28, 100%) and in 68.2% (15/22) of lower-extremity cases; the single patient with bilateral involvement was successfully managed at both sites (p = 0.003, Fisher-Freeman-Halton exact test). In 70% of all cases and 80% of magnet successful cases, the image intensifier was not used. Stratified analysis by anatomical location revealed that the inverse relationship between image-intensifier use and magnet-only success was particularly pronounced in lower extremity cases (p = 0.020).

Magnet-assisted extraction is an easy and feasible method with high success rates for MFB removal. The use of a magnet may reduce radiation exposure during MFB removal. Its efficacy decreases at lower-extremity sites, particularly in the sole, and with needle-type foreign bodies. These findings indicate that magnetic extraction of MFBs should be planned according to anatomical location and foreign body type.