Atypical coalition between cuboid and lateral cuneiform: case report and literature review

Ricardo Luna-Vargas, Centro Articular Monterrey (CAM), Hospital “Hospitaria” in City Gral. Escobedo, Monterrery, N.L., Mexico
Rodolfo Peña-Arroyo, Centro Articular Monterrey (CAM), Hospital “Hospitaria” in City Gral. Escobedo, Monterrery, N.L., Mexico
Héctor E. García-Quiroz, Centro Articular Monterrey (CAM), Hospital “Hospitaria” in City Gral. Escobedo, Monterrery, N.L., Mexico
Fabricio Neira-Rodriguez, Centro Articular Monterrey (CAM), Hospital “Hospitaria” in City Gral. Escobedo, Monterrery, N.L., Mexico
Cesar F. Pedraza-Villarreal, Centro Articular Monterrey (CAM), Hospital “Hospitaria” in City Gral. Escobedo, Monterrery, N.L., Mexico
Jesús A. De Léon-Delgado, Centro Articular Monterrey (CAM), Hospital “Hospitaria” in City Gral. Escobedo, Monterrery, N.L., Mexico

Tarsal coalition, an abnormal tarsal bone fusion from defective segmentation, affects 1-6% of the population, with bilateral involvement in 50% of cases. While calcaneonavicular and talocalcaneal coalitions are most common, this report describes a rare case of a cuboid-lateral cuneiform coalition in a 60-year-old woman. Based on our literature review, only five cases have been previously documented. The patient presented with six months of right foot pain (rated 6/10 on the Visual Analog Scale [VAS]), exacerbated by weight-bearing activities, without trauma. Physical examination revealed medial tenderness without edema or joint limitation. Initial radiographs were normal, but magnetic resonance imaging (MRI) identified a fibrous/ cartilaginous coalition with bone edema. After unsuccessful physiotherapy, three methylprednisolone injections (40 mg/ session) reduced pain to VAS 2/10, avoiding surgery. This case is unique for its anatomical rarity and adult-onset presentation, contrasting with the typical second-decade onset. It emphasizes MRI’s critical role in atypical cases and challenges the futility of conservative options in refractory scenarios to other conservative treatments. By showing diagnostic pitfalls of radiographs and showcasing minimally invasive efficacy, this report enriches the sparse literature on atypical tarsal coalitions, advocating for MRI in adults with unexplained mechanical foot pain.

Keywords: Tarsal coalition. Cuboid. Cuneiform bones. Foot pain. Case report.