A bipartite medial cuneiform bone: a rare variant with symptomatic presentation and the classic "E-sign".

Background: Bipartite medial cuneiform bone (BMC) is located at the Lisfranc joint of the midfoot, and it represents a rare variant involving two separate ossification centers in the medial cuneiform bone. Although BMC is typically asymptomatic, it can become clinically relevant under conditions of trauma or chronic stress, affecting foot stability.

Case report: The current imaging report describes a 48-year-old female presenting with chronic dorsal midfoot pain, worsened by extended standing and ambulation. Physical examination indicated mild tenderness without swelling or ecchymosis. Magnetic resonance imaging (MRI) revealed a BMC with degenerative changes around the synchondrosis, indicating abnormal weight-bearing stress across the cuneiform segments. The patient underwent conservative management with nonsteroidal anti-inflammatory drugs (NSAIDs) and restricted weight-bearing, leading to a reduction in pain over four weeks. Surgical options, including excision and fusion, were discussed but reserved for potential recurrence and persistence. The present report further explores BMC's anatomical features, including its differentiation from fractures through imaging. BMC's horizontal cleavage plane, well-corticated edges, and distinct articulations differentiate it from a traumatic fracture.

Conclusion: Current literature on managing symptomatic BMC is limited, with treatment options varying from conservative approaches to surgical interventions for persistent symptoms. The present case highlights the importance of considering BMC in the differential diagnosis of midfoot pain or instability. Additionally, it enhances our understanding of the anatomical aspects of BMC and offers valuable insights into its clinical presentation, imaging characteristics, and management strategies.