Pediatric Wrist and Hand

Rare, although carpal injuries may be
underappreciated owing to difficulties in examining an injured child
and the limited ability of plain radiographs to detail the immature
skeleton.

The adjacent physis of the distal radius
is among the most commonly injured; this is protective of the carpus as
load transmission is diffused by injury to the distal radial physis,
thus partially accounting for the rarity of pediatric carpal injuries.

The cartilaginous anlage of the wrist
begins as a single mass; by the tenth week, this transforms into eight
distinct masses, each in the contour of its respective mature carpal
bone.

The appearance of ossification centers of
the carpal bones ranges from 6 months for the capitate to 8 years of
age for the pisiform. The order of appearance of the ossification
centers is very consistent: capitate, hamate, triquetrum, lunate,
scaphoid, trapezium, trapezoid, and pisiform (Fig. 46.1).

The ossific nuclei of the carpal bones
are uniquely protected by cartilaginous shells. As the child matures, a
“critical bone-to-cartilage ratio” is reached, after which carpal
fractures are increasingly common (adolescence).

The most common mechanism of carpal injury in children is direct trauma to the wrist.

Indirect injuries result from falls onto
the outstretched hand, with consequent axial compressive force with the
wrist in hyperextension. In children, injury by this mechanism occurs
from higher-energy mechanisms, such as falling off a moving bicycle or
fall from a height.

The clinical presentation of individual
carpal injuries is variable, but in general, the most consistent sign
of carpal injury is well-localized tenderness. In the agitated child,
however, appreciation of localized tenderness may be difficult, because
distal radial pain may be confused with carpal tenderness.

A neurovascular examination is important,
with documentation of distal sensation in median, radial, and ulnar
distributions, appreciation of movement of all digits, and assessment
of distal capillary refill.

Gross deformity may be present, ranging from displacement of the carpus to prominence of individual carpal bones.

Anteroposterior (AP) and lateral views of the wrist should be obtained.

Comparison views of the uninjured, contralateral wrist may be helpful.

The scaphoid is the most commonly fractured carpal bone.

The peak incidence occurs at age 15
years; injuries in the first decade are extremely rare, owing to the
abundant cartilaginous envelope.

Unlike adults, the most common mechanism
is direct trauma, with extraarticular fractures of the distal one-third
the most common. Proximal pole fractures are rare and typically result
from scapholunate ligament avulsion.

Clinical evaluation: Patients present with wrist pain and swelling, with tenderness to deep palpation overlying the

scaphoid and anatomic snuffbox. The snuffbox is typically obscured by swelling.

Radiographic evaluation: The diagnosis
can usually be made on the basis of AP and lateral views of the wrist.
Oblique views and “scaphoid views,” or views of the scaphoid in radial
and ulnar deviation of the wrist, may aid in the diagnosis or assist in
further fracture definition. Technetium bone scan, magnetic resonance
imaging, computed tomography, and ultrasound evaluation may be used to
diagnose occult scaphoid fractures.

This extremely rare injury occurs primarily from severe, direct trauma (e.g., crush injury).

Clinical evaluation reveals tenderness to
palpation on the volar wrist overlying the distal radius and lunate,
with painful range of motion.

Radiographic evaluation: AP and lateral
views of the wrist are often inadequate to establish the diagnosis of
lunate fracture because osseous details are frequently obscured by
overlapping densities.

Treatment

Complications

Extremely rare, but the true incidence
unknown owing to the late ossification of the triquetrum, with
potential injuries unrecognized.

The mechanism of fracture is typically direct trauma to the ulnar wrist or avulsion by dorsal ligamentous structures.

Clinical evaluation reveals tenderness to palpation on the dorsoulnar aspect of the wrist as well as painful range of motion.

Radiographic evaluation: Transverse
fractures of the body can generally be identified on AP views in older
children and adolescents. Distraction views may be helpful in these
cases.

Treatment

No specific discussions of pisiform fractures in the pediatric population exist in the literature.

Direct trauma causing a comminuted fracture or a flexor carpi ulnaris avulsion may occur in late adolescence.

Radiographic evaluation is typically unrevealing, because ossification of the pisiform does not occur until age 8 years.

Treatment is symptomatic only, with immobilization in an ulnar gutter splint until the patient is comfortable.

Extremely rare in children and adults.

The mechanism of injury is axial loading
of the adducted thumb, driving the base of the first metacarpal onto
the articular surface of the trapezium with dorsal impaction. Avulsion
fractures may occur with forceful deviation, traction, or rotation of
the thumb. Direct trauma to the palmar arch may result in avulsion of
the trapezial ridge by the transverse carpal ligament.

Clinical evaluation reveals tenderness to
palpation of the radial wrist, accompanied by painful range of motion
at the first carpometacarpal joint with stress testing.

Radiographic evaluation: Fractures are
difficult to identify because of the late ossification of the
trapezium. In older children and adolescents, identifiable fractures
may be appreciated on standard AP and lateral views.

Treatment:

Fractures of the trapezoid in children are extremely rare.

Axial load transmitted through the second
metacarpal may lead to dislocation, more often dorsal, with associated
capsular ligament disruption. Direct trauma from blast or crush
injuries may cause trapezoid fracture.

Clinical evaluation demonstrates
tenderness proximal to the base of the second metacarpal with painful
range of motion of the second carpometacarpal joint.

Radiographic evaluation: Fractures are
difficult to identify secondary to late ossification. In older children
and adolescents, they may be identified on the AP radiograph based on a
loss of the normal relationship between the second metacarpal base and
the trapezoid. Comparison with the contralateral, normal wrist may aid
in the diagnosis. The trapezoid, or fracture fragments, may be
superimposed over the trapezium or capitate, and the second metacarpal
may be proximally displaced.

Treatment

Uncommon as an isolated injury owing to its relatively protected position.

A fracture of the capitate is more
commonly associated with greater arc injury pattern (transscaphoid,
transcapitate perilunate fracture-dislocation). A variation of this is
the “naviculocapitate syndrome,” in which the capitate and scaphoid are
fractured without associated dislocation.

The mechanism of injury is typically
direct trauma or a crushing force that results in associated carpal or
metacarpal fracture. Hyperdorsiflexion may cause impaction of the
capitate waist against the lunate or dorsal aspect of the radius.

Clinical evaluation reveals point
tenderness as well as variable painful dorsiflexion of the wrist as the
capitate impinges on the dorsal rim of the radius.

Radiographic evaluation: Fracture can
usually be identified on the AP radiograph, with identification of the
head of the capitate on lateral views to determine rotation or
displacement. Distraction views may aid in fracture definition as well
as identification of associated greater arc injuries. Magnetic
resonance imaging may assist in evaluating ligamentous disruption.

Treatment: Splint or cast immobilization
for 6 to 8 weeks may be performed for minimally displaced capitate
fractures. Open reduction is indicated for fractures with extreme
displacement or rotation to avoid osteonecrosis. Fixation may be
achieved with Kirschner wires or compression screws.

Complications

There are no specific discussions in the literature concerning hamate fractures in the pediatric population.

The mechanism of injury typically
involves direct trauma to the volar aspect of the ulnar wrist such as
may occur with participation in racquet sports, softball, or golf.

Clinical evaluation: Patients typically
present with pain and tenderness over the hamate. Ulnar and median
neuropathy can also be seen, as well as rare injuries to the ulnar
artery.

Radiographic evaluation: The diagnosis of
hamate fracture can usually be made on the basis of the AP view of the
wrist. Fracture of the hamate is best visualized on the carpal tunnel
or 20-degree supination oblique view (oblique projection of the wrist
in radial deviation and semisupination). A hamate fracture should not
be confused with an os hamulus proprium, which represents a secondary
ossification center.

Treatment: All hamate fractures should be
initially treated with immobilization in a short arm splint or cast
unless compromise of neurovascular structures warrants exploration.
Excision of fragments is generally not necessary in the pediatric
population.

Complications

Biphasic distribution: These injuries are
seen in toddlers and adolescents. The injuries are typically crush
injuries in toddlers and are typically related to sports participation
in adolescents.

The number of hand fractures in children
is higher in boys and peaks at 13 years of age, which coincides with
participation of boys in organized football.

The annual incidence of pediatric hand
fractures is 26.4 per 10,000 children, with the majority occurring
about the metacarpophalangeal joint.

Hand fractures account for up to 25% of all pediatric fractures.

As a rule, extensor tendons of the hand insert onto epiphyses.

At the level of the metacarpophalangeal
joints, the collateral ligaments originate from the metacarpal
epiphysis and inset almost exclusively onto the epiphysis of the
proximal phalanx; this accounts for the high frequency of Salter-Harris
Type II and III injuries in this region.

The periosteum of the bones of the
pediatric hand is usually well developed and accounts for intrinsic
fracture stability in seemingly unstable injuries; this often serves as
an aid to achieving or maintaining fracture reduction. Conversely, the
exuberant periosteum may become interposed in the fracture site, thus
preventing effective closed reduction.

The mechanism of hand injuries varies
considerably. In general, fracture patterns emerge based on the nature
of the traumatic force:

The child with a hand injury is typically
uncooperative because of pain, unfamiliar surroundings, parent anxiety,
and “white coat” fear. Simple observation of the child at play may
provide useful information concerning the location and severity of

injury. Game playing (e.g., “Simon says”) with the child may be utilized for clinical evaluation.

History: A careful history is essential because it may influence treatment. This should include:

Physical examination: The entire hand
should be exposed and examined for open injuries. Swelling should be
noted, as well as the presence of gross deformity (rotational or
angular).

A careful neurovascular examination is
critical, with documentation of capillary refill and neurologic status
(two point discrimination). If the child is uncooperative and nerve
injury is suspected, the “wrinkle test” may be performed. This is
accomplished by immersion of the affected digit in warm, sterile water
for 5 minutes and observing corrugation of the distal volar pad (absent
in the denervated digit).

Passive and active range of motion of
each joint should be determined. Observing tenodesis with passive wrist
motion is helpful for assessing digital alignment and cascade.

Stress testing may be performed to determine collateral ligament and volar plate integrity.

AP, lateral, and oblique radiographs of
the affected digit or hand should be obtained. Injured digits should be
viewed individually, when possible, to minimize overlap of other digits
over the area of interest.

Stress radiographs may be obtained in cases in which ligamentous injury is suspected.

The examiner must be aware that
cartilaginous injury may have occurred despite negative plain
radiographs. Treatment must be guided by clinical as well as
radiographic factors.

Impaired nail growth: Failure to repair
the nailbed adequately may result in germinal matrix disturbance that
causes anomalous nail growth. This is frequently a cosmetic problem,
but it may be addressed with reconstructive procedures if pain,
infection, or hygiene is an issue.

Extensor lag: Despite adequate treatment,
extensor lag up to 10 degrees is common, although not typically of
functional significance. This occurs most commonly at the level of the
proximal interphalangeal joint secondary to tendon adherence.
Exploration, release, and or reconstruction may result in further
cosmetic or functional disturbance.

Malunion: Apex dorsal angulation can
disturb intrinsic balance and also can result in prominence of
metacarpal heads in palm with pain on gripping. Rotational or
angulatory deformities, especially of the second and third metacarpals,
may produce

functional and cosmetic disturbances, thus emphasizing the need to maintain as near an anatomic relationship as possible.

Nonunion: Uncommon but may occur
especially with extensive soft tissue injury and bone loss, as well as
in open fractures with gross contamination and infection.

Infection, osteomyelitis: Grossly
contaminated wounds require meticulous debridement, appropriate
antibiotic coverage, and possible delayed closure.

Metacarpophalangeal joint extension
contracture: This may result if splinting is not in the protected
position (i.e., metacarpophalangeal joints at >70 degrees), owing to
soft tissue contracture.