- See:
-
Carpal Instability
-
Kinematics of the Wrist
- Discussion:
- lunate will tend to flex w/ loss of ulnar ligamentous support from the triquetrum;
- lunate extends when there is loss of radial ligamentous stability;
- DISI may arise as a result of:
-
scaphoid frx;
-
scapho-lunate dissociation;
-
perilunate dislocation (esp
trans-scaphoid perilunate dislocation);
- end result may be
SLAC wrist;
- Radiographic Analysis:
- on
lateral x-rays, when lunate slips into statically dorsiflexed position > 10 deg, condition is defned as DISI;
- similarly, when lunate lies palmar to capitate but faces dorsally, collapse pattern is also consistent w/ dorsiflexion instability;
- DISI deformity is also present when the scapholunate angle is greater than 70 deg;
- when diagnosising this condition, be sure that the lateral radiograph was taken w/ proper technique and that the
wrist is not dorsiflexed;
