Bipartite medial cuneiform.

Sagittal Short Tau Inversion Recovery (STIR) MR image, in a 35 year old female, demonstrates complete bipartition, with an arthrodial joint between the components. A tiny amount of fluid signal is present between the dorsal and plantar components of the bipartite medial cuneiform (arrow), similar to that seen at the ankle and naviculocuneiform joints.

Sagittal STIR image in a 52 year old male, demonstrates cortical irregularity along both components of a bipartite medial cuneiform (arrow heads), similar to the typical non-osseous coalitions seen elsewhere in the foot, suggestive of a syndesmosis and/or degenerative change. (Small varicosities are also noted.)

Sagittal T1 weighted MR images in a 30 year old male, who presented with ankle pain, demonstrate an obliquely oriented intra-articular fracture through the medial cuneiform (arrow heads), with adjacent bone marrow edema, tiny butterfly fragment anteriorly (arrow), and no cortication.

Sagittal T1-weighted MR image in a 35 year old female, demonstrates the classic "E-sign", described by Elias et al.

Conclusion

Bipartite medial cuneiform is a rare, congenital segmentation anomaly of the foot, which is most often incidental and asymptomatic. The bipartite medial cuneiform can be differentiated from a fracture by the characteristic appearance on MRI and radiographs, including the “E-sign”, well corticated margins, the size of the combined cuneiform segments, the size of the base of the first metatarsal, and edema pattern. Rarely, a bipartite medial cuneiform can be symptomatic, in which case surgery has proven successful in alleviating symptoms.

Reference