A New Variant of Type I Congenital Ulna Deficiency With the Normal Thumb, Webspace, Hand, and Elbow.

Unilateral congenital ulna deficiency of wrist and forearm is rare. It is associated with cartilaginous ulnar anlage, absence of ulnar digits, carpus, partially or completely absent ulna, radiohumeral synostosis, syndactyly, and thumb abnormalities. Various classifications have described this presentation. We report a new variant of type I congenital ulnar deficiency in wrist and forearm with a normal thumb, first webspace, hand, wrist, and elbow in an 18-year-old girl.