- See:
Carpal Instability
- Discussion:
- by definition, consists of volar flexion of the lunate relative to the longitudinal axis of the radius and capitate, when the wrist rests in a neutral position;
- lunate will tend to flex when there is loss of ulnar support from the triquetrum;
- may result from disruption of radial carpal ligaments on ulnar side of wrist & is characterized by scapholunate angle < 30 deg;
- volar flexion instability pattern is usually associated w/
triquetrolunate dissociation or triquetral-hamate instability;
- the dorsal-radial-triquetral and triquetro-scaphoid ligaments have an increase space (increased "V") between them;
- see:
ligaments of the wrist
- Static VISI:
- when lunate slips into a statically fixed position > 15 deg of flexion;
- early treatment: closed reduction and casting (w/ or w/o
K wires);
- Dynamic VISI:
- normal wrist may assume a VISI pattern when relaxed, however, this is not considered abnormal unless it is symptomatic;
- etiology may be a laxity in the volar capitotriquetral ligament;
- these patients may note pain on volar stress testing;
- radiographs may show a widening between the capitate and the triquetrum, when wrist is placed in radial deviation;
- treatment: capitolunate fusion;
- Radiographs: lateral view of wrist;
- Management:
-
space of Poirier is reenforced and is closed, which closes down the space between the triquetro-hamate and triquetro-capitate ligaments;
Volar Intercalated Segment Instability Secondary to Medial Carpal Ligamental Laxity. WP Garth Jr MD, DY Hofammann MD, and MD Rooks MD.
CORR No 201, Dec 1985, pp 94-105.
Traumatic instability of the wrist. RL Linscheid, JH Dobyns, and JW Beabout, and RS Bryan. JBJS 54A, 1612, 1972. p 94.
Intercarpal arthrodesis for static and dynamic volar intercalated segment instability.
Kinematics of the ulnar carpus related to the volar intercalated segment instability pattern.
