INTRODUCTION
Definition
A branchial arch syndrome with a complex osseous-syndactyly (severe type of fused digits).
Epidemiology
- Incidence is 1/80,000 live births.
- More common in boys (M:F=1.5:1).
Etiology
Most new cases are sporadic but can be autosomal dominant due to mutation in FGFr2 gene with aberrancy of the fibroblast growth factor receptor-2 (FGF-2).
- Leads to premature fusion of growth plates and suppressing of the selective apoptosis needed for separation of the digits.
Classification
Upton Classification: Guides decision-making.
- Type 1 (spade hand):
- Radial deviation of a small thumb with a shallow first web.
- The index, long, and ring fingers display complete or complex syndactyly.
- The little finger is attached by a simple complete or incomplete syndactyly.
- Treated with separation and contouring of the tips of the digits.
- Partial digit ablation may be required.
- Type 2 (mitten or spoon hand):
- The thumb is radially deviated and has an incomplete or complete simple syndactyly with the index.
- The index, long, and ring fingers are distally fused, creating a curve in the palm with divergent metacarpals.
- The little finger is attached to the ring with a mostly complete but simple syndactyly.
- Treated with separation of tips of digits and deepening of web space.
- Type 3 (rosebud hand):
- The thumb, index, long, and ring are distally fused either cartilaginous or bony attachments.
- The thumb can be very difficult to identify separately from the index.
- The little finger is united to the ring by simple complete syndactyly. The nails can be confluent.
- Proximal synostosis at the base of the fourth to fifth metacarpal can be present, as well as carpal fusions.
- The border digits are reconstructed first.
CLINICAL FEATURES
Characteristics
- Bilateral complex syndactyly of hands and feet.
- Acrosyndactyly: So-called spadelike hand. Fusion of the digits occurs distally, with proximal fenestrations.
- Craniosynostosis (premature closure of cranial sutures): There is a high, flattened and broad forehead, occipital flattening, and bulging.
- Symphalangism: Ankylosis/fusion of interphalangeal joints.
- Often radial clinodactyly of the thumb (curvature of a digit).
- Radioulnar synostosis.
- Glenoid hypoplasia.
- Decreased mental capabilities/mental retardation with impairment in language development and motor skills.
- Low-set eye, decreased eyesight and strabismus.
- Hyperhidrosis.
- Decreased hearing
Signs
- The patient has a dysmorphic face
- Rosebud hands (complex syndactyly where the index, middle, and ring finger share a common nail).
DIAGNOSIS
Conventional Radiography
Will show complex syndactyly.
TREATMENT
Overview
Treatment goals: Create a more useful extremity with the ability to grip or perform pincer grasp in as few operations as possible with staged reconstruction.
- Separation of digits, including the thumb.
- Correction of thumb function.
- Mobilization of the little finger.
Operative Treatment
Surgical release of border digits: Often the first step in surgical treatment. Done at 1 year of life. Digits-thumb and small finger are released first.
- First stage: Deepening or creation of the 1st web space with a a 4-5 limb Z-plasty or dorsal skin graft.
- Second stage: Creation of the 4th web space followed by separation of the remaining digits.
Digital reconstruction:
- Performed when the patient is 1.5-2 years of age.
- The middle 3 digits are turned into 2 digits.
Separation of proximal metacarpal synostosis:
- The synostosis should be separated early to improve mobility of the fifth ray.
PROGNOSIS AND COMPLICATIONS
Prognosis
- The spectrum can be from normal to moderately disabled cognitive function.
- Hand function and prognosis is best with the combination of thumb and little finger separation. This allows a tripod pinch and thumb based grip.
- Movement of the fingers is typically isolated to the metacarpal phalangeal joints.
Complications
- The need for revision surgery of web space contracture varies among authors from 3-18%.
- Aberrant growth plates can cause clinodactyly after separation and osteotomies may be needed later on.