VISI (Volar Intercalated Segment Instability)

Definition

• A carpal instability pattern where the lunate tilts volarly (flexes), decreasing the scapholunate angle < 30°.
• Represents failure of normal coordination between the lunate and triquetrum.

Clinical Significance

• May be incidental finding in ligamentously lax individuals
• If symptomatic: ulnar-sided wrist pain, decreased grip strength
• Consider provocative testing or wrist arthroscopy for confirmation

Mechanism

• Lunotriquetral ligament disruption → triquetrum extends, lunate follows scaphoid into flexion

Causes

• Lunotriquetral ligament injury (trauma)
• Congenital ligamentous laxity (normal variant in some)
• Rarely associated with rheumatoid arthritis

Frequency and Relevance

• Much less common than DISI
• Often seen in asymptomatic individuals with hyperlaxity → can be a normal variant
• Clinical correlation is essential before labeling it pathologic

Imaging Findings

• Lunate tilted volarly on lateral wrist view
  • Scapholunate angle < 30° (normal = 30–60°)
• No widening of SL interval
• Evaluate for signs of instability or degenerative changes

Management

• Asymptomatic or hyperlaxity-related: No treatment needed
• Symptomatic or traumatic: Splinting, physiotherapy, possible surgical repair