Dorsal Intercalated Segmental Instability (DISI)

Dorsal intercalated segmental instability results from injury to the radial side of the wrist. There is dorsal angulation of the lunate relative to radius resulting in a capitolunate angle > 20°. Scapholunate dissociation is usually (but not always) present, leading to a scapholunate angle > 60°. On the frontal view, the dorsal and volar margins of the distal lunate (arrows) are not superimposed as they normally are.