Painful conditions affecting the first metatarsal sesamoid bones.

The sesamoid bones of the first metatarsal exhibit a special anatomic configuration, enveloped by the tendons of the flexor hallucis brevis and lying within the capsule of the first metatarsophalangeal joint. Painful conditions of the hallux sesamoid bones are many and include congenital, traumatic, arthritic, infectious, and ischemic conditions. Because of the complex anatomy and the numerous pain-sensitive structures in the region of the first metatarsophalangeal joint, a differential diagnosis can be challenging. The imaging examination should always begin with conventional radiography, including special axial and lateromedial views of the sesamoid bones. In cases in which results of routine radiography are inconclusive, scintigraphy, conventional or computed tomography, xeroradiography, or magnetic resonance imaging can be used. A thorough understanding of the anatomy; pathophysiology; and clinical, laboratory, and imaging findings is often helpful in the establishment of a diagnosis and management plan for painful conditions of the hallux sesamoid bones.