AAOS Comprehensive Orthopaedic Review
Section 3 - Pediatrics
Chapter 31. Congenital Hand and Wrist Anomalies and Brachial Plexus Palsies
I. Embryology, Development, and Classification
1. The limb bud first appears during the fourth week of gestation; the upper limb develops during the fifth to eighth week of gestation.
2. Several signaling centers are critical for upper limb development
a. The apical ectodermal ridge guides proximal-to-distal development and mediates interdigital necrosis.
b. The zone of polarizing activity guides radioulnar development.
c. The Wnt signaling center guides dorsoventral development.
3. Joint motion is required for joint development in utero.
B. Developmental milestones—Although these are highly variable, general guidelines are listed in
[Table 1. General Developmental Milestones for Hand and Upper Limb Function]
C. Radiographic appearance of secondary centers of ossification
1. Carpal bones ossify in a predictable sequence:
a. Capitate (3 to 4 months)
b. Hamate (4 to 8 months)
c. Triquetrum (2 to 3 years)
d. Lunate (4 years)
e. Scaphoid (4 to 5 years)
f. Trapezium (5 years)
g. Trapezoid (6 years)
h. Pisiform (6 to 8 years)
2. Most common carpal coalition: lunotriquetral.
D. Classification of congenital hand differences—Classification based on embryologic development is currently accepted by the International Federation of Societies for Surgery of the Hand (IFSSH) (
[Table 2. Embryologic Classification of Congenital Anomalies]
Figure 1. Clinical photograph of the hand of a child with preaxial polydactyly.]
A. Preaxial polydactyly (Figure 1)
1. Also referred to as thumb duplication, thumb polydactyly, or "split thumb"
2. Incidence reported to be approximately 1 per 1,000 to 10,000 live births
a. Males more commonly affected than females; whites more commonly affected than blacks
b. Typically sporadic; associated congenital anomalies rare (except type VII)
a. Wassel classification most commonly used (
b. Wassel type IV (43%) and type II (15%) most common
a. Both the radial and ulnar components have structures that must be preserved and reconstructed to provide a stable, mobile, and functional thumb.
b. In Wassel type II, the radial digit has the radial collateral ligament insertion and the ulnar digit has the ulnar collateral ligament insertion of the interphalangeal (IP) joint.
[Figure 2. Wassel classification of preaxial polydactyly.]
c. In Wassel type IV, the thenar muscles insert on the more radial digit and the adductor pollicis inserts on the more ulnar digit.
d. Pollex abductus is an abnormal connection between the extensor pollicis longus (EPL) and flexor pollicis longus (FPL) tendons, seen in approximately 20% of hypoplastic and duplicated thumbs; presence of a pollex abductus is suggested by abduction of the affected digit and absence of IP joint creases.
5. Surgical treatment
a. Typically involves ablation of the bony elements of the more underdeveloped (usually radial) thumb and reconstruction of the (radial) collateral ligament and, in Wassel type IV thumbs, transfer of the thenar muscles from the ablated proximal phalanx to the preserved (ulnar) proximal phalanx.
b. Chondroplasty of the metacarpal head and/or corrective osteotomy of an abnormally shaped phalanx or metacarpal may need to be performed to restore the longitudinal alignment of the thumb.
Figure 3. Clinical photograph of the hand of a child with postaxial polydactyly.]
c. The Bilhaut-Cloquet procedure is technically difficult and often results in an aesthetically unpleasing thumb with physeal mismatch and articular incongruity.
d. Pollicization is recommended for unrecontructable or triphalangeal thumbs.
e. Approximately 15% to 20% of patients develop late deformity following surgery. Causes include failure to recognize a pollex abductus, inadequate correction of the longitudinal thumb alignment, inadequate reconstruction of the collateral ligament, and failure to centralize the extensor and/or flexor tendons.
B. Postaxial polydactyly (Figure 3)
1. Refers to duplication of ulnarmost digit
2. Inheritance is autosomal dominant (AD) with variable penetrance; affects blacks more than whites or Asians.
a. Type A: extra digit fully developed
b. Type B: extra digit is rudimentary and pedunculated
4. Treatment is surgical excision of extra digit.
a. In type A, reconstruction of collateral ligament and hypothenar muscle insertions may be needed (akin to thumb duplication).
Figure 4. PA radiograph of the arm of a child with radial longitudinal deficiency. Note the absent radius, bowed ulna, and radially deviated wrist.]
b. Type B postaxial polydactyly may be treated with suture ligature of the base of the pedicle in the newborn nursery.
A. Radial longitudinal deficiency (RLD)—Also known as radial dysplasia, radial clubhand.
1. Longitudinal failure of formation of the radial side of the forearm, wrist, and hand (Figure 4)
2. RLD is associated with several congenital conditions and syndromes:
a. Thrombocytopenia-absent radius (TAR)—Low platelet count that normalizes over time.
b. Fanconi anemia—Platelet and blood cell counts normal at birth but decrease dramatically during first few years of life; diagnosed with mitomycin-C chromosomal challenge test; treated with bone marrow transplantation.
c. Holt-Oram syndrome—RLD with congenital heart disease, typically atrial or ventricular septal defects.
d. VACTERL—Constellation of anomalies including vertebral, anal, cardiac, tracheal, esophageal, renal, and limb.
3. Clinical features
a. Elbow flexion contracture
b. Shortened and/or bowed forearm
c. Radial deviation of the wrist
d. Aplasia or hypoplasia of the thumb
4. In addition to skeletal deficiencies, there are similar deficiencies of soft-tissue structures (eg, radial artery, median nerve, flexor carpi radialis).
5. Bayne classification
a. I: delayed appearance of distal epiphysis, slightly shortened radius
b. II: deficient growth proximal and distal, considerably shortened radius
c. III: partial absence of the radius (distal and middle thirds most common)
d. IV: completely absent radius (most common)
a. Splinting and/or serial casting are initiated early to stretch the tight radial soft tissues.
b. Surgical procedures include centralization (axis of the ulna realigned with long metacarpal) or radialization (ulna is realigned with index metacarpal).
c. Surgery is not recommended in the setting of elbow stiffness or in older patients who have compensated/adjusted to their deficiency.
B. Ulnar longitudinal deficiency (ULD)—Also known as ulnar dysplasia, ulnar clubhand.
1. Longitudinal failure of formation of the ulnar forearm, wrist, and hand
2. 5 to 10 times less common than RLD; usually sporadic with rare AD inheritance patterns
3. Associated congenital anomalies occur less commonly than with RLD and include syndactyly, thumb duplication or hypoplasia, elbow instability, radial head dislocation, and synostosis.
4. Clinical features
a. Shortened and bowed forearm
b. Typically, the wrist is stable but elbow function is compromised.
5. Bayne classification
a. I: hypoplastic ulna with proximal and distal physes
b. II: absent distal ulna (most common)
c. III: completely absent ulna
d. IV: absent ulna with proximal radius fused to the distal humerus
6. Surgical options
a. Excision of the ulnar anlage
b. Corrective radial osteotomy
c. Corrective humeral osteotomy
d. Creation of a single-bone forearm
C. Thumb hypoplasia
1. Within spectrum of RLD, but classified as "undergrowth" by IFSSH classification
2. Often bilateral; males and females equally affected
3. Associated conditions include Holt-Oram, TAR, Fanconi anemia, and VACTERL
a. Buck-Gramcko modification of Blauth classification (
b. Type V most common (30% to 35% of cases), followed by type IV and type III
5. Clinical features of types I through IIIA
a. Tight first web space
b. IP joint stiffness
c. Metacarpophalangeal (MCP) instability
d. Absence of thenar musculature
6. Treatment—depends on type
a. I: no treatment
b. II through IIIA: surgical reconstruction (first web deepening, MCP stabilization, and opponensplasty)
c. IIIB through V: index pollicization with or without ablation of thumb. In the treatment of thumb hypoplasia, pollicization is recommended in the setting of an underdeveloped or unstable carpometacarpal (CMC) joint (Blauth types IIIB through V).
d. Principles of pollicization
i. Use of local skin flaps to reconstitute first web space
ii. Bony reduction to recreate metacarpal and phalanges of pollex (
Figure 6) in appropriate position (120° to 140° pronation, 15° extension, 40° palmar abduction)
iii. Transfer of index finger on neurovascular pedicles to new position
iv. Tendon transfers (extensor digitorum communis [EDC] to abductor pollicis longus [APL], extensor indicis proprius [EIP] to EPL, first dorsal interosseous [DIO] to abductor pollicis brevis [APB], first volar interosseous [VIO] to adductor pollicis [AdP])
[Figure 5. Buck-Gramcko modification of the Blauth classification for thumb hypoplasia. STT = scaphotrapeziotrapezoid, MCP = metacarpophalangeal, UCL = ulnar collateral ligament, CMCJ = carpometacarpal joint.]
1. Nonvascularized toe phalanx transfer useful
2. Prerequisite is appropriate soft-tissue pocket at recipient site
3. Best if performed at young age (<12 to 18 months)
4. Presence of open physis after transfer is 94% if performed before 1 year of age, 71% between 1 and 2 years, and 48% after 2 years of age.
E. Transverse deficiencies (congenital amputations)
1. Typically sporadic, unilateral, and not associated with other conditions
2. Transradial amputation most common
3. Fitting with a passive terminal prosthesis recommended at 6 months ("sit to fit")
4. Free vascularized toe transfer(s) may be considered for congenital amputations at the level of the hand.
1. "Overgrowth" according to IFSSH classification
2. Typically unilateral, involving radial digits
[Figure 6. Drawings showing index finger pollicization for thumb aplasia. A, Blauth grade V hypoplasia of the thumb. B, The index finger is reduced and rotated. The inset demonstrates the turning of the metacarpal head for prevention of hyperextension deformity. C, The metacarpal head is anchored down (arrow).]
3. Usually isolated, but may occur in setting of neurofibromatosis, Proteus syndrome, or Klippel-Trenaunay-Weber syndrome
4. May be static or progressive; with asymmetric digital nerve involvement, may result in radioulnar or flexion deformity
a. Type I: macrodactyly and lipofibromatosis; most common type, associated with fibrofatty proliferation in the distribution of a digital or peripheral nerve, which is typically enlarged and tortuous
b. Type II: macrodactyly and neurofibromatosis
c. Type III: macrodactyly and hyperostosis
d. Type IV: macrodactyly and hemihypertrophy
6. Surgical options
a. Include soft-tissue debulking, epiphysiodesis of affected phalanges, bony and soft-tissue reduction procedures, and amputation
b. Individualized according to the anatomic distribution, degree of deformity, and skeletal growth remaining
V. Amniotic Band Syndrome
1. Also referred to as constriction ring syndrome or amniotic disruption sequence
2. Reported incidence: 1 in 15,000 live births
3. Sporadic, not hereditary
4. Commonly associated with other anomalies (eg, clubfoot, cleft lip/palate, craniofacial defects)
2. Endogenous and exogenous theories of causation have been proposed.
3. Prevailing theory is that amniotic disruption releases strands of membrane that circumferentially wrap around the developing upper limb.
C. Clinical presentation—Bands typically lie perpendicular to longitudinal axis of the affected digit/limb (
1. More than 90% occur distal to wrist.
2. Central digits more commonly affected
[Figure 7. Clinical photograph of the hand of a child with amniotic band syndrome.]
3. Varying depths of constriction
4. If no amputation, secondary syndactyly or bony fusions may occur with proximal epithelialized sinus tracts
5. Key: normal anatomy proximal to constriction ring
D. Classification—Patterson, 1961
1. I: simple constriction ring
2. II: deformity distal to ring (lymphedema, hypoplasia)
3. III: fusion of distal parts
4. IV: amputation
1. Type I: observation versus excision/release of constriction ring
2. Type II: excision of constriction ring with local flaps (Z-plasty)
3. Type III: syndactyly release
4. Type IV: Function may be improved with reconstructive procedures, including bony lengthenings, web deepenings, "on top" plasties, nonvascularized toe phalanx transfers, or free vascularized toe transfers.
1. Failure of differentiation resulting in webbed fingers.
Figure 8. Clinical photograph of the hand of a child with complete syndactyly of the second and third web spaces.]
2. Most common congenital hand difference, occurring in 1 per 2,000 to 2,500 live births
3. Males affected more commonly than females; whites affected more commonly than blacks
4. Inheritance: AD with variable penetrance
B. Associated conditions
1. Poland syndrome: congenital absence of the sternocostal head of the pectoralis major, limb hypoplasia, synbrachydactyly
2. Apert syndrome (also known as acrocephalosyndactyly): mental retardation; premature fusion of cranial sutures resulting in high, broad fore-head, occipital flattening, and bulging low-set eyes; and acrosyndactyly (spadelike hand)
3. Carpenter syndrome: acrocephalopolysyndactyly
1. Simple syndactyly defined by web formed by soft tissue only (Figure 8).
2. Complex syndactyly denotes fusion of adjacent phalanges.
3. Complicated syndactyly refers to interposition of accessory phalanges or abnormal bones.
4. Complete syndactyly refers to webbing that extends to the tips of the involved digits.
5. Incomplete syndactyly does not extend to the digital tips.
6. The third web is most commonly affected, followed by the fourth, second, and first web spaces.
D. Treatment principles
1. Release digits of differing sizes first to avoid growth disturbance.
2. Do not operate on both sides of the digit at the same time to avoid vascular embarrassment.
3. Use local skin flaps to reconstitute the web commissure to avoid scar contracture and "web creep."
4. Use zigzag lateral flaps to avoid longitudinal scar contracture.
5. Use full-thickness skin grafts to cover bare areas.
1. Failure of differentiation of the IP joint, usually of ulnar digits
2. Characterized by absence of flexion/extension creases and digital stiffness
3. Joint space may appear narrow on radiographs.
4. Capsulectomies/arthroplasties have met with limited success.
5. Osteotomy or arthrodesis may be considered at maturity, although rarely needed due to adequate digital function.
1. Refers to flexion contracture/deformity of finger
2. True incidence is unknown; it is estimated that 1% of the population is affected.
3. Little finger and proximal interphalangeal (PIP) joint most commonly affected
4. Usually sporadic, but some exhibit AD inheritance with variable penetrance
1. Type I: presents in infancy
2. Type II: presents in adolescence
3. Type III: occurs in setting of underlying syndrome
1. Nearly every structure about the base of the finger has been implicated as causal.
2. Abnormal lumbrical insertion and adherent or hypoplastic flexor digitorum sublimis (FDS) most commonly cited
3. Other causes theorized
a. Skin contracture
b. Absent central slip/extensor tendon
c. Articular incongruity
d. Abnormal volar plate
e. Abnormal oblique retinacular ligament
D. Treatment principles
1. Splinting and stretching exercises may be attempted, but these often have mixed results.
2. Surgical treatment is indicated for significant flexion contracture with functional impairment, but this often has limited results.
a. All identifiable pathology should be addressed (eg, anomalous lubrical insertion).
b. For passive deformity, consider FDS tenotomy or transfer to the radial lateral band.
c. For fixed deformity, consider osteotomy versus arthrodesis.
E. Kirner deformity (
1. Progressive, nonpainful volar-radial curvature of little finger distal phalanx
2. Typically affects preadolescent females, usually bilaterally
3. Sporadic or AD
4. Unknown etiology, but likely due to disturbance of distal phalangeal physis
5. Usually an aesthetic concern, but not functionally limiting
6. Corrective osteotomy can be considered at the completion of growth.
F. Trigger thumb
1. Caused by constriction of FPL tendon at A1 pulley
2. Not thought to be congenital
3. Likelihood of spontaneous resolution 30% if younger than 1 year, <10% if older than 1 year
4. Surgical treatment: A1 pulley release
G. Trigger finger
1. Much less common than trigger thumb
2. Caused by anomalous anatomy, including abnormal lumbrical insertion and/or proximal decussation of FDS tendon
3. Association with other conditions, including mucopolysaccharidoses
4. Surgical treatment
a. Release of A1 pulley alone may not suffice; recurrence rates up to 50%
[Figure 9. PA (A) and lateral (B) radiographs of the hand of a child with Kirner deformity.]
b. Requires extensile exposure, release of A1 pulley, and addressing anomalous anatomy (release of lumbrical; A1, partial A2, A3 release; excision of single slip of FDS)
1. Refers to angular deformity of digit in the radioulnar plane.
2. True incidence unknown; estimated between 1% and 10% of population
3. Typically bilateral, little finger most commonly affected
4. AD inheritance
5. Many syndromic associations (including trisomy 21)
B. Classification (Cooney)
1. Simple (bony deformity alone) versus complex (soft-tissue involvement)
2. Uncomplicated (15° to 45° angulation) versus complicated (>45° angulation with rotation)
1. Clinodactyly is usually more of an aesthetic concern than a functional problem.
2. Splinting/stretching may be initiated, although it is often ineffective.
3. Surgery is indicated for severe deformity with functional compromise (eg, digital overlap).
D. Delta phalanx
1. If the proximal physis is not oriented perpendicular to the long axis of the phalanx, this may result in triangular- or trapezoidal-shaped bone with progressive angular deformity—the so-called delta phalanx.
2. The shortened side of phalanx contains the longitudinal epiphyseal bracket.
3. For significant deformity and functional limitations, surgical options include physiolysis or corrective osteotomy.
IX. Brachial Plexus Birth Palsy
1. Definition: Brachial plexus birth palsy (BPBP) is a traction or compression injury sustained to the brachial plexus during birth.
2. Incidence reported to be 0.1% to 0.4% of live births
3. Risk factors include macrosomia, shoulder dystocia/difficult delivery, prior BPBP.
1. Anatomic: upper trunk, lower trunk, total plexus
2. Neurologic: avulsion, rupture, neurapraxia
C. Natural history
1. Few long-term prospective data are available.
2. 80% to 90% of patients demonstrate spontaneous recovery.
3. If antigravity biceps function recovers by 2 months, full recovery is anticipated.
4. If biceps function recovers at or after 5 months, incomplete recovery is likely.
5. Presence of Horner syndrome portends worse prognosis.
D. Indications—Indications for microsurgery remain controversial.
1. Absent return of biceps function at 3 to 6 months
2. Flail extremity (total plexus injury) in setting of Horner syndrome at 3 months
E. Microsurgical treatment
1. Avulsion injuries: consider nerve transfers/neurotizations
2. Nerve ruptures: excision of neuroma, nerve grafting
F. Glenohumeral dysplasia—In setting of persistent muscular imbalance across the developing shoulder, there is progressive dysplasia of the glenohumeral joint, with posterior subluxation of the humeral head, humeral head flattening, and increased glenoid retroversion.
G. Secondary procedures
1. Tendon transfers: latissimus dorsi and teres major tendon transfers to rotator cuff (Sever-L'Episcopo procedure), often combined with releases of the pectoralis major, subscapularis, and coracobrachialis muscles, to improve shoulder abduction and external rotation
2. Humeral osteotomy: external rotation osteotomy of the distal humeral segment; recommended in setting of advanced glenohumeral joint dysplasia
Top Testing Facts
1. RLD is commonly associated with other congenital anomalies, including TAR, Fanconi anemia, Holt-Oram syndrome, and VACTERL association.
2. In the treatment of thumb hypoplasia, pollicization is recommended in the setting of an underdeveloped or unstable CMC joint (Blauth types IIIB through V).
3. Amniotic band syndrome usually occurs distal to the wrist and typically involves the central digits.
4. When performing syndactyly release, only one side of an affected digit should be operated on at a time to avoid vascular embarrassment.
5. Failure of antigravity biceps recovery by 3 to 6 months is an indication for microsurgery in BPBP.
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