Sonographic detection of occult fractures in the foot and ankle

The purpose of this retrospective study was to determine whether high-resolution sonography can aid in the diagnosis of radiographically occult fractures in the foot and ankle.

High-resolution sonography with a 10-MHz linear-array transducer was performed in 268 patients with foot and ankle injuries whose initial plain x-ray films were negative for fracture.

Twenty-four patients had occult fractures demonstrated by sonography. On sonography, the occult fractures appeared as a discontinuity of cortex echogenicity. The fractures were found at the calcaneus (n = 8), metatarsus (n = 6), talus (n = 3), navicular bone (n = 3), cuboid bone (n = 2), cuneiform bone (n = 1), and lateral malleolus (n = 1). Review of the patients' radiographs revealed tiny fractures at the sonographically identified locations in 2 patients. The first 5 patients underwent bone scans, which confirmed the presence of the fractures. The first 11 patients received follow-up sonographic examination 6 weeks after diagnosis; in all 11, an echogenic line over the previous fracture site, presumably representing callus formation, was noted.

Sonography-a readily available, noninvasive imaging technique-can provide important information about soft tissue injuries and cortical discontinuities in the foot and ankle area. Using this procedure, occult fractures can be identified and delineated, and costly procedures such as MRI can be avoided.