The spectrum of radial longitudinal deficiency: a modified classification

The records of 119 patients with 196 extremities with radial longitudinal deficiency seen between 1923 and 1996 were reviewed. We propose a global classification system that includes the spectrum of pathology affecting the radial side of the extremity, including deficiency of the radius, carpal abnormalities, and hypoplastic thumbs. Radial deficiency could be classified for 181 extremities of 104 patients using this classification system. Type N has a normal length radius and a normal carpus with thumb hypoplasia, type O has a normal length radius and radial side carpal abnormalities, type 1 has more than 2 mm shortening of the radius, type 2 has a hypoplastic radius, type 3 has a partial radius with absence of the distal physis, and type 4 has complete absence of the radius. All patients had thumb hypoplasia. Eighty-two percent of extremities with thumb hypoplasia but no deficiency of the radius that were available for carpal bone classification had carpal anomalies, including absence, hypoplasia, and coalitions. All the extremities with type 1 radial deficiency had carpal anomalies. Carpal abnormalities could not be determined for types 2, 3, and 4 deficiency because most had a prior centralization. Proximal radioulnar synostosis or congenital dislocation of the radial head was seen in 44% of extremities with type 1 radial deficiency. This classification includes carpal anomalies and thereby links isolated thumb hypoplasia and deficiency of the radius into one system.