ABSTRACT
Ulnar deficiency is the most common term for the great variety of congenital deformities of the ulnar border of the hand and forearm, extending up to the shoulder. Synonyms are ulnar club hand, congenital absence or defect of the ulna, longitudinal arrest of development of the ulna, ulnar dysmelia, aplasia/hypoplasia of the ulna, and ulna hemimelia. This diversity of the terminology also reflects differences in the conception of which cases should be included. It seems to be logical to classify hands with a reduced number of digital rays (oligodactyly) as a first (slightest) group of ulnar deficiency, even if the ulna is normal, because all deformities at the ulnar border of the hand and arm are collected under this term. However, we have decided to omit discussion of the oligodactylous hand with a normal ulna-mainly in comparison with the radial club hand, to which thumb deformities will not belong if the radius is normal.
