Coalition of the proximal row of the carpus.

The human carpal bones, as in most mammals, are usually eight in number, and develop from a common embryological origin by the eighth week of intrauterine life 1. Failure of separation during this development leads to the phenomenon of carpal coalition. The prevalence of the anomaly is uncertain as it is usually asymptomatic 2. Individual cases have been reported which have presented as unusual causes of wrist pain, through arthritis or fracture 3, or even tendon rupture 4. The case reported here shows bilateral lunate-triquetral coalition with unilateral synostosis of the pisiform and triquetrum.