Pure isolated medial talonavicular joint dislocation following low-energy trauma: a case report

Midtarsal dislocations are relatively rare injuries secondary to high-energy trauma and are typically accompanied by disruption of ligamentous structures and fractures of the midfoot. We herein present a case of a pure isolated medial swivel dislocation of the talonavicular joint (TNJ) that was sustained following low-energy trauma without an associated fracture. A 78-year-old woman visited our emergency department with severe pain in the midfoot area of the right foot without neurovascular deficits. She had sustained this injury after severe ankle inversion while going downstairs. Plain radiographs of the right foot showed that the navicular was dislocated medially on the talus; no other malalignments were present. Three-dimensional computed tomography revealed dislocation of the TNJ, but no other tarsal or midtarsal bone fractures or dislocations. A medial dorsal incision was made to expose the TNJ. The dorsal talonavicular ligament was ruptured and interposed between the navicular and talus. The ligament was removed and the TNJ was reduced. The clinical outcome at the 1-year follow-up was satisfactory with no limitations in daily activities. In summary, we have reported an extremely rare case of a pure isolated medial TNJ dislocation in which the interposed dorsal talonavicular ligament served as an obstacle to reduction.