Anatomic features of metatarsal heads that simulate erosive disease: cadaveric study using CT, radiography, and dissection with special emphasis on cross-sectional characterization of osseous anatomy.

Abstract

The purpose of our study was to characterize and describe normal osseous contours of the metatarsal heads that may simulate erosive changes. CT of the metatarsal heads was performed in six human cadaveric feet, and 3D reformatted images were analyzed. Subsequently, five feet were sectioned in planes corresponding to those at imaging for anatomic correlation, and one foot was anatomically dissected for correlation. The normal anatomic osseous contours of the metatarsal heads were analyzed and described. Normal osseous anatomy of the greater (first) and lesser (second through fifth) metatarsal heads was identified. The normal osseous landmarks that simulate erosive changes were identified. Variations in the normal anatomic osseous contours, including those related to the medial and lateral condyles, were present in all specimens. The lateral condyle of the first metatarsal head was found to be more prominent than the medial condyle. In addition, anatomic variations in the normal osseous concavities of the lateral and medial aspects of each metatarsal head were measured. An intersesamoidal ridge, present on the plantar surface of the first metatarsal head, was identified in all specimens. The normal anatomic contours of the metatarsal head are a potential major source for diagnostic error when viewing sectional CT and MR images in patients with suspected erosive arthritis. These normal variations, although common and varied, produce characteristic findings that can be differentiated from bone erosions.