Presentation
Midfoot pain without a clear history of trauma.
Patient Data
A well-corticated bony structure is seen between the bases of the first and second metatarsals that articulates with the adjacent first metatarsal shaft, compatible with os intermetatarseum.
Metatarsophalangeal sesamoids are evident adjacent to all five metatarsals' heads.
There is also an os naviculare.
Mild degenerative changes as subchondral sclerosis are observed in the first metatarsophalangeal and midtarsal joints.
Case Discussion
The os intermetatarseum is an uncommon accessory ossicle of the foot that is usually asymptomatic. However, it can cause dorsal midfoot pain and is typically positioned dorsally between the bases of the first and second metatarsals. It can be free-standing, articulating or fused with adjacent bony structures.