dorsal intercalated segment instability

Dorsal intercalated segment instability (DISI) is a form of instability involving the wrist. It occurs mainly after the disruption of the scapholunate ligament and is more often encountered than volar intercalated segment instability (VISI).

Clinical presentation

  • radial or dorsal wrist pain, maximal on radial deviation and wrist extension
  • weakness and/or instability
  • clicking wrist
  • positive Watson test: during ulnar to radial deviation, pressure applied to the volar aspect of the scaphoid elicits an audible and/or palpable clunk (due to dorsal subluxation of the scaphoid with respect to the radius)



Radiographic features

Fixed DISI deformity only occurs after combined injury of scapholunate ligament and other stabilizers of the scaphoid, namely radioscaphocapitate and scaphocapitate ligaments.

Plain radiograph

On an AP view, the normal trapezoidal configuration of the scaphoid may be lost and it may appear triangular.

On the lateral radiograph with the wrist in a neutral position, DISI typically demonstrates dorsal tilt of the lunate with both of the following present:


On sagittal CT, the same findings as on plain radiograph are seen.


On sagittal MRI , the same findings as on plain radiograph are seen. However, bone contusion, scaphoid avascular necrosis and scapholunate ligament injury are evaluated with more precision.

See also

Siehe auch:
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