Cleft Hand

Etiology

Typical cleft hand deformities are the result of an inherited autosomal dominant trait. The central rays develop differently from the thumb and small finger, and this mutation disrupts the central digit growth in the hands and often the feet. Atypical cleft hands, in contrast, are a result of a sporadic mutation and are therefore not inherited or associated with syndromic conditions.[2]

Epidemiology

The incidence of typical cleft hands is 1 in 90,000 births and 1 in 120,000 within the population. Atypical cleft hands occur in 1 in 150,000 births and 1 in 200,000 within the population. Bilateral cleft hands are observed in 56% of patients, while unilateral deformity is present in 44% of cases.[8]

History and Physical

Cleft hands are congenital disorders, and significant deformities are present at birth. An understanding of the exact deformity is critical to guide treatment. Family history for similar malformations will be suggestive of a typical cleft hand deformity, whereas an absence of family history will be more indicative of a sporadic mutation.

Clinicians should perform a careful assessment of the vasculature of the hand, ensuring the hand is well perfused as atypical cleft hands associated with Poland syndrome are a result of vascular hypoplasia. Furthermore, an examination of the ipsilateral chest wall will help to guide management. Absence or hypoplasia of the pectoralis musculature will be further evidence of vascular insufficiency at the subclavian artery and may necessitate staged surgical release of symbrachydactyly given the underlying poor vasculature.

Evaluation

Radiographs help guide the classification and surgical management of cleft hand deformities. Before undergoing any surgical treatment, surgeons must develop a plan that specifically addresses the patient's unique abnormality. In particular, surgeons must assess for the presence or absence of metacarpals in the central rays, the degree of symbrachydactyly that may be present, and especially the vascular supply to the hand. If the cleft hand is due to vascular insufficiency, as is the case in Poland syndrome, a staged surgical correction will be necessary.

Treatment / Management

While surgical management of a cleft foot is comparatively straightforward, surgical management of a cleft hand is variable and largely dependent on underlying anatomy. A small first web space between the thumb and index finger can be detrimental to the functional use of the hand, as the thumb is unable to have the same range of motion and lever arm present in an anatomically normal first webspace. Therefore, the functional goal of most surgeries is to split the cleft in half with an incision that wraps from the cleft and around the index finger into the first webspace. Often a flap from the ulnar half of the cleft is used to increase the depth of the first webspace, ultimately creating a wider and more functional space between the index finger and the thumb. Details of each surgical procedure are unique and based on each patient’s presenting deformity. Soft tissue releases, transfers, and osteotomies of the metacarpals may be necessary to achieve a more functional alignment.[9](B2)

Differential Diagnosis

Poland syndrome is attributed to subclavian hypoplasia leading to malformations of the limb during development. It is characterized by unilateral chest wall hypoplasia, symbrachydactyly, and shortening of the central fingers. When a unilateral atypical type cleft hand presents, clinicians should be aware of its association with Poland syndrome and evaluate for deficiency of the pectoralis musculature. In this scenario, patients who require syndactyly release should undergo surgery one digit at a time to avoid any vascular complications, as the underlying deficiency is due to vascular insufficiency during development.[10][11]

Prognosis

A cleft hand has been described as "a functional triumph and a social disaster," referring to the high degree of functionality of most hands with this deformity despite its atypical and malformed appearance.[3] Even so, surgical intervention, in most cases, improves the appearance of the hand without significantly affecting the functional outcome. In cases where the function is impaired, as when the first webspace is hypoplastic, surgical alignment of the hand often results in improved usage and cosmetic outcomes.[9]

In one study, researchers followed 23 patients with a cleft hand after having undergone surgical intervention to correct their deformities. Twenty-two of the 23 were satisfied with the aesthetics of the hand after surgical intervention, and 21 of the 23 reported being "satisfied" or "very satisfied" with their functional outcome. The most common complaint after surgery is digital stiffness.[3]

Complications

Patients who have a cleft hand due to a vascular deformity are at high risk for skin loss and poor perfusion of the surgical site after surgery, particularly if the procedure does not have appropriate staging. Furthermore, stiffness of the digits remains the most common postoperative complaint despite improved overall functional outcomes.