Isolated complete dislocation of the tarsal navicular without fracture: A rare injury.

Injuries to the midtarsal joints usually occur in various combinations such as fracture, fracture subluxation, and fracture dislocation. Isolated dislocations of the navicular bone without fracture are rare injuries. The few existing case reports describe the probable mechanism of injury and optimal treatment. We present a 64-year-old diabetic man whose tarsal navicular was completely dislocated without fracture following a traffic accident. The most probable mechanism of injury was an abduction-pronation injury causing a midtarsal dislocation, and on spontaneous reduction, the navicular was dislocated medially. This mechanism is similar to perilunate dislocation. Computed tomography of the involved foot was done to accurately define the full extent of the bony injury and magnetic resonance imaging was required to determine if there was a ligamentous injury and to assess the attachment of soft tissues to the displaced bone to help assess the risk of avascular necrosis. The patient was treated successfully with open reduction and primary talonavicular arthrodesis with Kirschner wires.