A, Normal scapholunate and capitolunate angles. B, Dorsal intercalated segmental instability (DISI) deformity of wrist. Concave surface of lunate points dorsally, scapholunate angle is greater than 80 degrees, and capitolunate angle is greater than 20 degrees. C, Volar intercalated segmental instability (VISI) deformity of wrist. Concave surface of lunate points palmarly, and scapholunate angle is less than 30 degrees.