The treatment of wrist instability

The concept of carpal instability has evolved considerably over the past few years. Initially, the term ‘instability ’ was considered to be synonymous with ‘malalignment’.1-3 A wrist was regarded as unstable when there was an alteration of the sagittal and/or anteroposterior alignment of the car-pal bones beyond what was judged to be normal.4,5 Based on this, four major types of carpal malalignment were recognised: Dorsal intercalated segment instability (DISI). The lunate, regarded as an intercalated segment between the distal row and the forearm bones, is abnormally extended relative to its proximal and distal links. Volar intercalated segment instability (VISI). In the sagittal plane the lunate appears abnormally flexed. Ulnar translocation. The proximal row is abnormally dis-