Abstract
Carpal instability is a complex array of maladaptive and posttraumatic conditions that lead to the inability of the wrist to maintain anatomic relationships under normal loads. Many different classification schemes have evolved to explain the mechanistic evolution and pathophysiology of carpal instability, including 2 of the most common malalignment patterns: volar intercalated segment instability and the more common dorsal intercalated segment instability. Recent classifications emphasize the relationships within and between the rows of carpal bones. Future research is likely to unify the disparate paradigms used to describe wrist instability.