In a midtarsal dislocation, the cuboid and navicular dislocate from the talus and calcaneum. The joint may dislocate medially (with an adduction force), or laterally (with an abduction force).
These dislocations may be associated with fractures of the tarsal bones (particularly the navicular), or with smaller avulsion fractures.
In major foot injuries, always obtain a lateral x-ray of the foot (click on the x-ray to enlarge) in addition to the usual AP and oblique views. Similarly if standard x-rays show a fracture of the navicular, obtain a lateral x-ray of the foot.
If there is a significant mechanism of injury and a lot of swelling, but the x-rays appear normal or relatively normal, consider requesting a CT scan.