Congenital anomalies of the upper extremity occur in approximately one out of 626 live births. The most widely accepted clinical classification of congenital limb anomalies was adopted by the American Society for Surgery of the Hand, International Federation of Societies for Surgery of the Hand, and International Society for Prosthetics and Orthotics. This work was designed to organize anomalies according to embryonic failure during development. This classification relies on the clinical diagnosis, and each limb malformation is categorized into one of seven categories according to its predominant anomaly (Table 1). Different clinical presentations of similar categories are explained by varying degrees of damage during embryogenesis.

Group I is divided into transverse or longitudinal failure of formation. Transverse deficiencies are also called congenital amputations and are termed according to the anatomic level of limb termination. The most common site of amputation occurs at the proximal third of the forearm (Fig. 1). Rudimentary digits can be located on the end of the amputation stump. A fetal vascular insult to the developing limb is the most prevalent explanation for these deficiencies. Early chorionic villous sampling and failed attempts at pregnancy termination by dilatation and curettage have been associated with transverse limb deficiencies.

Longitudinal deficiencies are named according to bones that are partially or completely absent. These deficiencies can be divided into radial (preaxial), ulnar (postaxial), or central forms. The central type includes deficiencies of the index, long, and ring rays (digits and underlying carpus). The typical cleft hand has a V-shaped deficiency involving at least the long ray (Fig. 2). This type is often bilateral, familial, and includes the feet. In contrast, an atypical cleft deformity is also known as symbrachydactyly and has a U-shaped deficiency. The extent and number of affected digits are variable and can range from mild deficiencies of the central rays to a monodactylous or adactylous hand. This type is usually unilateral, nonfamilial, and without involvement of the feet.

Radial deficiencies are approximately ten times more common than their ulnar complement. Exposure to teratogens such as thalidomide and radiation can cause radial deficiencies, although the majority of cases are sporadic without


any definable cause. Of all radial deficiencies, 50% are bilateral. The types vary depending on the amount of radius missing. The most common form has a complete absence of the radius and is often associated with thumb hypoplasia. The remaining ulna is always decreased in length (approximately 60% of normal). This discrepancy persists throughout the growth period. The ulna is thickened and frequently bowed toward the absent radius. The wrist is positioned in radial deviation and eventually becomes perpendicular to the forearm (Fig. 3). Radial deficiency is associated with numerous syndromes; the most common are Holt-Oram (cardiac septal defects), TAR (thrombocytopenia, absent radius), Fanconi’s anemia (aplastic anemia), and VACTERL (vertebral, anal, cardiac, tracheoesophageal, renal, and limb abnormalities). These syndromes require appropriate evaluation in any child with a radial deficiency.