Symptomatic lunate-triquetral coalition.

Carpal coalitions are an uncommon anatomic anomaly caused by the failure of segmentation of the carpal cartilaginous anlage. The most common carpal coalition is between the lunate and triquetrum. Previously considered completely asymptomatic, carpal coalition and associated degenerative arthritis of the incompletely involved joints has been proven as a cause of occult wrist pain.