Symptomatic carpal coalition.

The carpus is initially a cartilaginous structure that subsequently demarcates into separate carpal bones. Failure of differentiation of parts results in carpal coalition, the most common of which occurs between the lunate and triquetrum. Lunate-triquetral coalitions can be subdivided into four types according to the degree of union. Four types are identified. A case report of type I is presented that responded to a lunate-triquetral fusion.