Cleft Hand

Presentation

Cleft hand or central longitudinal deficiency, historically described as typical and atypical hand, is a deficiency affecting the central hand and rarely involving structures proximal to the wrist. Central longitudinal deficiencies consist of deficiencies of bony and soft tissue structures centrally in the hand plate with a variable degree of ablation of the middle finger ray or central digits, syndactyly, polydactyly, and variable deficiency of the first web space.

The typical cleft hand is bilateral, with a V-shaped defect from varying degrees of central ray absence and more commonly metacarpals present with absent phalanges. Syndactyly of the remaining digits and foot involvement are more common with the typical cleft hand.

Atypical hand, now known as symbrachydactyly, is usually unilateral with the presence of digital nubbins and a more U-shaped cleft. The U-shaped cleft appearance is attributed to the absence of the index, long, and ring fingers from necrosis of mesenchymal tissue, with present metacarpals. Ogino classified this deformity on the basis of the grade of osseous syndactyly and polydactyly.

Reconstruction options are focused on improving function by syndactyly releases, deepening the thumb/first web space, and correcting the central deficiency more for esthetic (as opposed to functional) improvements. Suggesting that absence of central digits normally do not affect function as much as the insufficient first web space does. Manske and Halikis based their classification on the thumb web or first web space, which helps guide the treatment plan of restoring hand function ( Table 5.5.1 ).

Etiology

Cleft hand can occur sporadically and can also be inherited as an autosomal dominant condition with variable penetrance and expressivity. A defect or mutation in the apical ectodermal ridge activity produces clefting, but the exact causation and chromosomal defect are unknown. The cleft defect is created through deficiencies in the surrounding soft tissue, causing the available space and bones to either fuse or form in malalignment. Split hand/split foot malformation is known to be genetically related and is caused by a mutation in the p63 gene on 3q27. Atypical cleft hand or symbrachydactyly is primarily a bone formation disturbance and can have bone missing with abnormal soft tissues.

Associated Conditions

Cleft hand is associated with multiple syndromes ( Box 5.5.1 ) and a variety of general and limb defects. Although a majority of occurrences are isolated, cleft hand can be associated with syndromes such as ectrodactyly-ectodermal dysplasia-clefting (EEC) syndrome, de Lange syndrome, and split hand/split foot with mandibulofacial dysostosis. Limb defects can include clubfoot, tibia defects, elbow synostosis, radioulnar synostosis, absent ulna, and cleft feet. General defects can consist of cleft lip and palate, congenital heart disease, imperforate anus, nystagmus, cataracts, deafness, and undescended testes.

Atypical hand or symbrachydactyly typically is not associated with foot involvement or systemic conditions, but can be associated with Poland syndrome. Therefore the ipsilateral chest wall must be examined for a hypoplastic pectoralis major muscle.