Key Words
cleft hand, central longitudinal deficiency, typical, atypical, syndactyly, symbrachydactyly
Synopsis
Cleft hand, or central longitudinal deficiency, is characterized by a V-shaped defect, absence of 1 or more central digits, syndactyly or other abnormalities of bordering digits, and a deficient first web space. Cleft hand is an autosomal-dominant condition with variable penetrance that manifests from a defect in the apical ectodermal ridge of the limb bud with some cases involving new mutations. Cleft hand can be associated with multiple syndromes and general defects as well as upper and lower limb defects.
The key principles in reconstruction of cleft hands are syndactyly separation, first web space deepening, and cleft closure. Cleft closure is not necessarily needed for function; Nutt and Flatt termed the condition “a functional triumph and a social disaster.”
Timing of surgery is usually around 1 year of age with the aim to be done with all surgeries at 2 years of age.
The Snow-Littler procedure is used for severe clefts, which consists of closure of the cleft, deepening of the first web space, and transposition of index finger to a central digit position. The size of the central flap can make perfusion unreliable, and wound care is often needed for partial flap loss. Web creep is common and may need revision web deepening.
Clinical Problem
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 ).
| Type | Description | Characteristics |
|---|---|---|
| I | Normal web | |
| IIA | Mildly narrowed web | |
| IIB | Severely narrowed web | |
| III | Syndactylized web | |
| IV | Merged web | Index ray suppressed |
| V | Absent web | Only ulnar rays present |
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.
de Lange dwarfism
Oculodigital complex
Orodigital complex
Otodigital complex
Silver-Russell syndrome
Ectrodactyly-ectodermal dysplasia-clefting (EEC) syndrome
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.
Pre-Operative Management
Physical Examination and Key Anatomy
Assessment of the degree of syndactyly, particularly the first web space, is very important. There can be varying degrees of deformities as well as surgeries to reconstruct these differences. However, there are some general principles that can be followed. Syndactyly between the bordering or adjacent digits of the cleft is common. Also, there can be angular deviation of the thumb that should be corrected to improve hand function.
Cleft closure should be avoided in hands with a missing index finger or with defects in three finger rays. The cleft hand itself can be rather functional, and reconstructing a hand that is narrower could create difficulty with function and grasp of larger objects. Function of the remaining digits should be assessed as well.
Radiographs are obtained to assess for osseous deficiencies, synostoses, and the presence of transversely or obliquely lying bones. With complete syndactyly of digits, there could be synostosis of bones, shared flexor tendons, pulleys, and neurovascular bundles.
Pre-Operative Testing Needed/Patient Selection
Decisions regarding treatment should be made jointly with the family. Discussion is centered on risks of possibly losing function while improving the esthetics of the hand. The primary goal is a hand with good grasp and pinch; the secondary goal is improved esthetic appearance. The most beneficial functional outcome is usually from deepening of the first web space. The strongest indication for surgery is the presence of a transverse bone or “crossbone” because the cleft will widen, further affecting function and esthetics.
Optimal Timing of Surgery
Timing of surgery is typically at around 1 year of age. The first surgery usually includes the syndactyly separation (if present) of border digits (first and fourth web), with or without correction or removal of the delta phalanx from the thumb for angular deformities, followed by cleft closure. Surgeries should be completed by 2 years of age or at least before the patient is of school age. Surgery is done during this time period to encourage functional use of the hand after reconstruction. Typically, timing of any additional or revision surgeries is about 6 months after the syndactyly surgery. One must always be aware of anesthesia concerns from associated conditions that can include oral clefts and heart disease.
Surgery
Step-by-Step Technique Guide With a Representative Case
The equipment needed for cleft hand reconstruction is very simple, as noted in Box 5.5.2 . The Snow-Littler procedure was first described in 1967, with modifications by Miura and Komada in 1979 and others, stressing the importance of the first web space reconstruction. The main reasons for reconstruction are for syndactyly and a narrowed or deficient first web space.
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