Apert Syndrome (Pediatric)

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.

Table of Contents

1. Miller, M. and Thompson, S. (2016). Miller’s review of orthopaedics. 7th ed. Philadelphia, PA: Elsevier.
2. Boyer, M. (2014). AAOS comprehensive orthopaedic review 2. 2nd ed. Rosemont: American Academy of Orthopaedic Surgeons.
3. Posna.org. (2019). Apert Syndrome, Constriction Band Syndrome, Postaxial Polydactyly & Camptodactyly | Pediatric Orthopaedic Society of North America (POSNA). [Accessed 22 Aug. 2019].