20-year-old man presented with increasing pain corresponding to the plantar aspect of the second web (intermetatarsal) space for the past three years. The patient was active in sports, particularly football. His past medical history was notable for the presence of a bony prominence over the dorsomedial aspect of the right mid foot since birth. The patient stated that his father had the same bony prominence at the same location of the same foot. He did not complain of any symptoms related to the "bump" other than minor issues of fitting into shoes.
The patient had been seen by a podiatrist, who prescribed orthodics with limited relief of symptoms. The pain increased during exercise. He was referred by podiatry to orthopedic surgery for further evaluation.
Physical exam was notable for focal bony prominence at the dorsomedial aspect of the right mid foot without tenderness to palpation. The overlying skin was normal in coloration. Patient demonstrated an abnormal gait with persistent minor supination of the right forefoot. During gait, he appeared to bear weight on the second/third metatarsal heads rather than the first.
The first web space was noted to be narrowed with the first and second toes in close apposition without syndactyly. The second web space was widened. There was focal tenderness to palpation corresponding to the plantar second web space. MRI was ordered to exclude an osteochondroma.
Subsequent MRI demonstrated focal bony prominence projecting dorsally from the base of the first and second metatarsal bones in close apposition with typical appearance of non-osseous coalition (Fig. 1). Mild subchondral marrow signal and cystic changes are noted at this articulation. This finding corresponded to the focal bony prominence that the patient stated he had since birth.
Fusiform soft tissue is also noted at the plantar aspect of the second web space consistent with interdigital (Morton) neuroma (Fig. 2). This finding explained the patient's chief complaint of plantar foot pain at second web space.