Presentation
Pain along the plantar surface of the first metatarsophalangeal joint after foot trauma.
There is an irregular lucent line traversing the lateral sesamoid from anterior to posterior. The borders of this lucent line are not corticated. The transition from the lucent line to the outer convex surface of the sesamoid are sharp and angular, in keeping with fracture.
Case Discussion
Sesamoid fractures are uncommon, and may be mistaken for a simply bipartite sesamoid. The radiographic appearance in this case suggests fracture, as the fracture fragments are not corticated along the fracture line, together would be nearly exactly the same size as the medial sesamoid, and the fracture line is anteroposteriorly oriented instead of transversely. The history of trauma with pain specifically at this point should suggest the diagnosis as well. It may also be helpful to note that bipartite sesamoids are more common at the medial sesamoid, and therefore a bipartite lateral sesamoid should raise the level of suspicion in equivocal cases.