Carpal coalition with radioscaphoid synostosis and hypoplastic thumb.

Carpal coalition is an anomaly that is usually discovered as an incidental finding on roentgenograms. The most common site is between the lunate and the triquetrum, though fusion of almost every combination of carpal bones has been reported. Carpal coalition can be isolated but has also been associated with numerous congenital malformation syndromes. In this article, we report the case of a 12-year-old boy with left-sided asymptomatic fusion of the trapezoid and trapezium, fusion of the radius and scaphoid, and hypoplasia of the thumb.