Sonography of plantar plates in cadavers: correlation with MRI and histology

The purpose of our study was to describe the sonographic appearance of the lesser metatarsal plantar plates in cadavers and to correlate these findings with MRI and histology.

Six soft-embalmed cadaveric feet (74-92 years old; two male, one female) were imaged with sonography and MRI. Tear dimensions of the plantar plate were recorded in the long and short axes. Orthopedic surgeons directly inspected the plantar plates before removing samples for histologic correlation. One young fresh cadaver was imaged with sonography before histologic assessment.

The normal plantar plate appearance on sonography was a slightly echoic, homogeneous, curved structure. At direct inspection, a tear was present in 23 (96%) of 24 of the lesser plantar plates in the soft-embalmed feet. This direct inspection correlated with sonography detecting 23 tears correctly and MRI, 22 tears. Both sonography and MRI falsely reported one tear, but MRI also failed to detect one tear. Histologically, the abnormal plantar plate showed loss of the normal dense regular tissue and replacement with vessels, hydropic tissue, and a mixture of loose connective tissue and dense irregular connective tissue.

Sonography, being noninvasive, shows promise as an imaging tool of the plantar plate. With ongoing research in this area we hope to determine the reliability and significance of such a technique in the evaluation of the plantar plate.