24 Congenital Conditions of the Upper Extremity and Hand

Danielle A. Hogarth and Joshua M. Abzug


Congenital conditions affecting the upper extremity are observed in 1 in every 600 to 700 live births. These conditions derive from failure of upper limb development during gestation. Surgical intervention is often warranted to correct functional limitations and minimize aesthetic differences for both the child and their family. Conditions like syndactyly, polydactyly, thumb hypoplasia, and constriction band syndrome often undergo surgical intervention due to the limited potential complications but substantial functional and aesthetic benefits. Therapy and continual observation may be a more ideal treatment strategy for other conditions such as radial longitudinal deficiency or type I polydactyly if it does not infringe on prehension function or if the patient has been able to compensate accordingly. Should surgical intervention be elected, it typically is performed within the first 2 years of age or soon after functional limitations are present. Corrective surgeries of congenital conditions affecting the hand aim to provide bilateral symmetry, adequate prehension, and regain functional upper extremity ability for children while minimizing aesthetic differences, where possible.

24 Congenital Conditions of the Upper Extremity and Hand

I. Embryology

  • Congenital hand differences vary in their functional and aesthetic implications.

  • Rapid limb bud development occurs between weeks 4 and 8 of fetal gestation. 1 , 2

  • Fibroblast growth factors regulate sonic hedgehog (SHH) gene which is responsible for proper limb structures development from the limb bud.

  • Understanding the affected axis can provide insight on the underlying etiology of the abnormality:

    • Apical ectodermal ridge (AER): Regulates longitudinal growth. 2

    • Zone of polarizing activity (ZPA): Regulates development of ulnar and radial structures and other growth about the anteroposterior axis. 2

    • Wnt signaling pathway: Determines development of dorsal and ventral structures. 2

II. Polydactyly

A. Incidence

  • 1 per 300 to 1 per 3,000 births.

  • More common in African–American population than Caucasian.

  • Type IV is the most common (43%) followed by Type II (15%).

B. Etiology/Genetics

  • Typically, unilateral and random.

  • Exact etiology is not well known.

C. Classification

  • Duplication ofdigits.

  • Preaxial: Thumb duplication (Wassel classification; ► Fig. 24.1 and ► Table 24.1).

  • Central: Duplication at the midline.

  • Postaxial: Small finger duplication (► Fig. 24.2):

    • Type A: Well-formed digit articulating with the fifth metacarpal.

    • Type B: Skin tag or a rudimentary pedunculated digit (► Fig. 24.2). 3

Fig. 24.1 Radiograph of bilateral preaxial polydactyly: Left thumb Wassel Type II, right thumb Wassel Type I. (Courtesy of Joshua M. Abzug, MD)
Fig. 24.2 Clinical photograph of a Type B postaxial polydactyly. (Courtesy of Joshua M. Abzug, MD)

Table 24.1 Wassel classification of preaxial polydactyly

Type I

Bifid distal phalanx with a common epiphysis which articulates with a normal proximal phalanx typically seen with two distinct nails with a groove between them

Type II

Complete duplication of distal phalanx—each phalanx has its own epiphysis which articulates with the normal proximal phalanx

Type III

Duplicated distal phalanx with a bifurcated proximal phalanx that typically diverge from the longitudinal axis

Type IV

Complete duplication of proximal phalanx—each phalanx has its own epiphysis or a common epiphysis that articulates with a normal metacarpal or a slightly widened metacarpal to accommodate both proximal phalanges

Type V

Bifurcated first metacarpal—each head of the bifurcation articulates with a duplicated proximal phalanx that has its own epiphysis

Type VI

Complete duplication of the metacarpal and entire first digit

Type VII

Triphalangeal thumb or elements of a triphalangeal thumb accompanying by a normal thumb

D. Treatment

1. Surgical Treatment

  • Preaxial: Goal is to reconstruct a thumb that attains bilateral symmetry while preserving pinch function:

    • Types I, II, and III: Bilhaut-Cloquet procedure involves removing central tissue and combining both digits into one.

    • Types III and IV: Type 2 combination technique preserves skeleton and nail of one component and augment with soft tissue from other digit; ablation of lesser digit.

    • Types V, VI, and VIII: Type 3 combination technique involves segmental digital transfer.

  • Central: Goal is to remove extra digit in order to prevent angular growth deformities.

    • Osteotomy and ligamentous reconstructions.

  • Postaxial: Goal is typically to remove lesser digit:

    • Type A: Reconstruction with Type 2 combination technique preserves radial digit, radial collateral ligaments, and muscular structures.

    • Type B: Suture ligation—tie off in nursery or amputate before age 1, essentially inducing avascular necrosis to the rudimentary digit.

III. Syndactyly

A. Incidence

  • Seen in 1 per 2,000 to 3,000 live births. 1 , 4 , 5

  • More prevalent in males than in females.

B. Etiology/Genetics

  • Autosomal dominant.

  • Syndactyly occurs secondary to failure of apoptotic mechanisms that typically create webspaces between digits between weeks 6 and 8 of gestation. 6

  • Disturbed Wnt signaling and gap junction protein function lead to syndactyly. 2

  • Associated conditions:

    • Constriction band syndrome.

    • Poland’s syndrome.

    • Apert syndrome.

    • Carpenter’s syndrome.

C. Classification

  • Connection of adjacent digits (► Fig. 24.3).

  • Described by degree of connection:

    • Complete: Connected the full length of the digits (► Fig. 24.3a).

    • Incomplete: Proximal connection of adjacent fingers (► Fig. 24.3b).

  • Described by type of connected tissue:

    • Simple: Connected by skin only.

    • Complex: Skeletal, muscular, and cutaneous fusion of adjacent digits

  • Synechia: Unique condition where all digits (index to small) are completely connected as well as a connection between the nail plates.

Fig. 24.3 Clinical photographs of (a) a complete long-ring-small syndactyly status post separation of the tips of the ring and small fingers and (b) an incomplete long-ring syndactyly. (Courtesy of Joshua M. Abzug, MD)

D. Treatment

  • Hand function and aesthetic preference are the primary determinants of whether surgical intervention is warranted.

1. Nonoperative Management

  • Simple, incomplete cases can be addressed according to patient and family’s preference as these presentations do not substantially limit hand function.

2. Surgical Treatment

  • Digit release

    • Complete, complex syndactyly with nail involvement (flag and pennant technique—use skin from pulp of each digit to reconstruct the lateral nail fold).

      • Interdigitating zigzag flaps to avoid longitudinal scarring.

    • Partial syndactyly can be treated with skin flaps with possible application of skin grafts or skin graft alternatives:

      • Island flaps.

      • Three-square flap.

  • Full-thickness skin grafts are standard to obtain skin coverage following digital separation.

E. Complications

  • Recurrent web creep or resyndactylization is the most common complication following digital release.

IV. Thumb Hypoplasia

A. Incidence

  • 1 per 30,000 live births. 7

B. Etiology/Genetics

  • Exact etiology is not well known. 8

  • On the radial longitudinal deficiency spectrum; therefore, associated organ system conditions may be affected as well. 8

    • VACTERAL (vertebral defects, anal atresia, cardiac defects, tracheo-esophageal fistula, renal anomalies, and limb abnormalities).

    • Holt—Oram syndrome.

    • Thrombocytopenia absent radius (TAR).

    • Fanconi anemia.

C. Classification

Fig. 24.4 Clinical photograph of a Type IIIB hypoplastic thumb: (a) preoperative and (b) status post index finger pollicization. Note the unstable thumb carpometacarpal joint preoperatively. (Courtesy of Joshua M. Abzug, MD)

Table 24.2 Blauth classification of hypoplastic thumb

Type I

Minor hypoplasia—slightly decreased thumb size

Type II

Narrowed first webspace, hypoplastic thenar musculature, unstable MCP joint

Type III

A: Stable CMC joint; extrinsic muscle abnormalities B: Unstable CMC joint; extrinsic muscle abnormalities

Type IV

Pouce flottant or floating thumb

Type V

Complete absence of thumb

Abbreviations: CMC, carpometacarpal; MCP, metacarpophalangeal.

D. Treatment

1. Nonoperative Management

  • Type I: Observation is warranted to ensure that thumb and hand function are not substantially limited.

2. Surgical Treatment

  • Stability of carpometacarpal (CMC) joint dictates whether reconstruction or pollicization procedures are indicated: 8 , 10

    • Type II: Oppensplasty to release the first webspace and increase range of motion. 10 , 11

    • Type IIIA: Thumb reconstruction.

    • Types IIIB, V, and VI: Ablation of the existing digit with subsequent pollicization procedure 11 , 12 (► Fig. 24.4).

V. Radioulnar Synostosis

A. Incidence

  • Very rare congenital disorder with only 350 cases reported in the literature. 13

  • Affects males more than females.

B. Etiology/Genetics

  • Failure of differentiation of the cartilaginous precursors into the radius and ulna in week 7 of gestation.

  • One out of five cases positive with family history: Autosomal dominant inherence pattern.

  • Associated conditions in 30% of cases:

    • Apert syndrome

    • Carpenter’s syndrome

    • Arthrogryposis

    • Mandibulofacial dysostosis

    • Klinefelter’s syndrome

    • Sex chromosome abnormalities

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Jun 20, 2021 | Posted by in Hand surgery | Comments Off on 24 Congenital Conditions of the Upper Extremity and Hand

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