Accuracy of radiography, computed tomography and magnetic resonance imaging in diagnosing foreign bodies in the foot.

PURPOSE: The purpose of this study was to determine the accuracy of conventional radiography, computed tomography (CT) and magnetic resonance imaging (MRI) in detecting foreign bodies by using cadaver feet. MATERIALS AND METHODS: One hundred and sixty foreign bodies consisting of 5 × 2-mm fresh wood, dry wood, glass, porcelain and plastic fragments were randomly placed in the plantar soft tissue of the forefoot and sole. An additional 160 incisions were made without the insertion of foreign bodies. Radiographs, CT and MRI scans were assessed in a blinded fashion for the presence of a foreign body. RESULTS: Overall sensitivity and specificity for foreign body detection was 29% and 100% for radiographs, 63% and 98% for CT and 58% and 100% for MRI. The sensitivity of radiography was lower in the forefoot. CT and MRI detection rates depended on the attenuation values of the foreign bodies and on the susceptibility artefact, respectively. CT was superior to MRI in identifying water-rich fresh wood. CONCLUSIONS: Radiography, CT and MRI are highly specific in detecting foreign bodies but sensitivity is poor. The detection rate depends on the type of foreign body for all techniques and on location for radiography. To identify foreign bodies with MRI, pulse sequences should be used to enhance the susceptibility artefact. In water-rich wood, as in chronically retained wood, CT is more accurate than MRI.

Intra-articular ossicle in interphalangeal joint of the great toe and clinical implication.

Failure of closed reduction for an interphalangeal joint dislocation of the great toe resulted from an intra-articular ossicle interposed between the articular cartilages of the phalanges. The knowledge concerning the intra-articular ossicle is unclear. A study was thus carried out on 100 fresh great toes to document the appearance, number, size, and location of the intra-articular ossicle found in the interphalangeal joint of the great toe. Roentgenographic studies of the joint revealed 86% of bony mass representing either the sesamoid bone or the intra-articular ossicle. Anatomical studies revealed no sesamoid bone in the flexor hallucis longus tendon. There was 88% of intra-articular ossicle on the dorsal surface of the plantar capsule of the interphalangeal joint. A medial surgical approach to reduce the irreducible dislocation is thus suggested as easier and safer than other approaches.