dorsal intercalated segment instability
Also written as: DISI — Dorsal Intercalated Segment Instability
A carpal instability pattern where the lunate tilts dorsally due to ligament injury.
Full Definition
Dorsal intercalated segment instability (DISI) is a carpal instability pattern characterized by dorsal tilting of the lunate bone due to disruption of the volar radiocarpal ligaments, particularly the radioscapholunate ligament. On lateral radiographs, the scapholunate angle exceeds 70 degrees, and the capitolunate angle shows dorsal angulation. This pattern commonly occurs with scapholunate dissociation but can also result from other ligamentous injuries. DISI represents adaptive changes as the carpus attempts to maintain stability after ligament disruption. Early recognition and treatment are important to prevent progressive carpal collapse and arthritis.
Usage
Usage note: Commonly abbreviated as DISI; distinguish from VISI pattern.
In Context
- "Lateral radiographs demonstrated classic signs of DISI with increased scapholunate angle." — Imaging interpretation
- "The patient developed progressive DISI deformity following untreated scapholunate ligament injury." — Follow-up examination