PEDIATRIC WRIST AND HAND

INJURIES TO THE CARPUS

Epidemiology

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.

Anatomy

The cartilaginous anlage of the wrist begins as a single mass; by the 10th 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).

Mechanism of Injury

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.

Clinical Evaluation

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.

Radiographic Evaluation

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

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

Scaphoid Fracture

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 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 anteroposterior (AP) and lateral views of the wrist. Oblique views and scaphoid views, or a posterior–anterior (PA) view in ulnar deviation of the wrist, may aid in the diagnosis or assist in further fracture definition. Technetium bone scan has been replaced with magnetic resonance imaging. Alternatively, computed tomography and ultrasound evaluation may be used to diagnose occult scaphoid fractures.

Classification (Fig. 46.2)

Type A: Fractures of the distal pole

A1: Extra-articular distal pole fractures

A2: Intra-articular distal pole fractures

Type B: Fractures of the middle third (waist fractures)

Type C: Fractures of the proximal pole

Treatment

A fracture should be presumed if snuffbox tenderness is present, even if a fracture is not obvious on plain radiographs. Initial treatment in the emergency department should consist of a thumb spica splint or cast immobilization if swelling is not pronounced. In the pediatric population, a long arm cast or splint is typically necessary for adequate initial immobilization. This should be maintained for 2 weeks, at which time repeat evaluation should be undertaken.

For stable, nondisplaced fractures, a long arm cast should be placed with the wrist in neutral deviation and flexion/extension and maintained for 6 to 8 weeks or until radiographic evidence of healing has occurred.

Displaced fractures in the pediatric population may be initially addressed with closed reduction and percutaneous pinning. Distal pole fractures can generally be reduced by traction and ulnar deviation.

Residual displacement >1 mm, angulation >10 degrees, or scaphoid fractures in adolescents generally require open reduction and internal fixation. A headless compression screw or smooth Kirschner wires may be used for fracture fixation, with postoperative immobilization consisting of a long arm thumb spica cast for 6 weeks.

Complications

Delayed union, nonunion, and malunion: These are rare in the pediatric population and may necessitate operative fixation with bone grafting to achieve union.

Osteonecrosis: Extremely rare in the pediatric population and occurs with fractures of the proximal pole in skeletally mature individuals.

Missed diagnosis: Clinical suspicion should outweigh normal appearing radiographs and a brief period of immobilization (2 weeks) can be followed by repeat clinical examination and further radiographic studies if warranted.

Lunate Fracture

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.

• Oblique views may be helpful, but computed tomography or technetium bone scanning are better for diagnosis.

Treatment

• Nondisplaced fractures or unrecognized fractures generally heal uneventfully and may be recognized only in retrospect. When diagnosed, they should be treated in a short arm cast or splint for 2 to 4 weeks until radiographic and symptomatic healing occurs.

• Displaced or comminuted fractures should be treated surgically to allow adequate apposition

  for formation of vascular anastomoses. This may be achieved with open reduction and internal fixation, although the severity of the injury mechanism typically results in concomitant injuries to the wrist that may result in growth arrest.

Complications

• Osteonecrosis: Referred to as “lunatomalacia” in the pediatric population, this occurs in children less than 10 years of age. Symptoms are rarely dramatic. Radiography reveals mildly increased density of the lunate with no change in morphology. Immobilization of up to 1 year may be necessary for treatment, but it usually results in good functional and symptomatic recovery.

  Triquetrum Fracture

Rare, but the true incidence is 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

• Nondisplaced fractures of the triquetrum body or dorsal chip fractures may be treated in a short arm cast or ulnar gutter splint for 2 to 4 weeks when symptomatic improvement occurs.

• Significantly displaced fractures may be amenable to open reduction and internal fixation.

   

  Pisiform Fracture

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.

Trapezium Fracture

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.

• Superimposition of the first metacarpal base may be eliminated by obtaining a Robert view or a true AP view of the first carpometacarpal joint and trapezium.

Treatment:

• Most fractures are amenable to thumb spica splinting or casting to immobilize the first carpometacarpal joint for 3 to 5 weeks.

• Rarely, severely displaced fractures may require open reduction and internal fixation to restore

  articular congruity and maintain carpometacarpal joint integrity.

  Trapezoid Fracture

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:

• Most fractures may be treated with a splint or short arm cast for 3 to 5 weeks.

• Severely displaced fractures may require open reduction and internal fixation with Kirschner wires with attention to restoration of articular congruity.

  Capitate Fracture

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

• Midcarpal arthritis: Caused by capitate collapse as a result of displacement of the proximal pole.

• Osteonecrosis: Rare and most often involves severe displacement of the proximal pole. It may

  result in functional impairment. This emphasizes the need for accurate diagnosis and stable reduction.

  Hamate Fracture

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

• Symptomatic nonunion: May be treated with excision of the nonunited fragment.

• Ulnar or median neuropathy: Related to the proximity of the hamate to these nerves and may require surgical exploration and release.

  INJURIES TO THE HAND

  Epidemiology

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 contact athletics.

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.

Anatomy (Fig. 46.3)

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 insert almost exclusively onto the epiphysis of the proximal phalanx; this accounts for the high frequency of Salter-Harris types 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.

Mechanism of Injury

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

• Nonepiphyseal: Torque, angular force, compressive load, direct trauma

• Epiphyseal: Avulsion, shear, splitting

• Physeal: Shear, angular force, compressive load

   

  Clinical Evaluation

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:

• Patient age

• Hand dominance

• Refusal to use the injured extremity

• The exact nature of the injury: crush, direct trauma, twist, tear, laceration, etc.

• The exact time of the injury (for open fractures)

• Exposure to contamination: barnyard, brackish water, animal/human bite

• Treatment provided: cleansing, antiseptic, bandage, tourniquet

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.

Radiographic Evaluation

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.

Treatment

General Principles

“Fight-bite” injuries: Any short, curved laceration overlying a joint in the hand, particularly the metacarpophalangeal joint, must be suspected of having been caused by a tooth. These injuries must be assumed to be contaminated with oral flora and should be addressed with broad-spectrum

antibiotics.

Most pediatric hand fractures are treated nonoperatively, with closed reduction using conscious sedation or regional anesthesia (e.g., digital block). Hematoma blocks or fracture manipulation without anesthesia should be avoided in younger children.

Finger traps may be utilized with older children or adolescents but are generally poorly tolerated in younger children.

Immobilization may consist of short arm splints (volar, dorsal, ulnar gutter, etc.) or metal finger splints. With conscientious follow-up and cast changes as indicated, immobilization is rarely necessary beyond 4 weeks.

Operative indications include unstable fracture patterns, in which the patient may benefit from percutaneous Kirschner wire fixation; open fractures, which may require irrigation, debridement, and secondary wound closure; and fractures in which reduction is unattainable by closed means— these may signify interposed periosteum or soft tissue that requires open reduction.

Subungual hematomas that occupy >50% of the nail plate should be evacuated with the use of a needle, cautery tip, or heated paper clip. There is reported a higher incidence of late nail deformities associated with failure to decompress subungual hematomas.

Nail bed injuries should be addressed with removal of the compromised nail, repair of the nail bed with 6-0 or 7-0 absorbable suture or some type of dermal glue, and retention of the nail under the nail fold as a biologic dressing to protect the healing nail bed. Alternatively, commercially made stents are available for use as dressings. Close attention should be paid to identify any associated bone or physeal injury of the phalanx.

Management of Specific Fracture Patterns

Metacarpals

Pediatric metacarpal fractures are classified as follows:

Type A: Epiphyseal and Physeal Fractures

Fractures include the following:

• Epiphyseal fractures

• Physeal fractures: Salter-Harris type II fractures of the fifth metacarpal most common

• Collateral ligament avulsion fractures

• Oblique, vertical, and horizontal head fractures

• Comminuted fractures

• Boxer’s fractures with an intra-articular component

• Fractures associated with bone loss

Most require anatomic reduction (if possible) to reestablish joint congruity and to minimize posttraumatic arthrosis.

• Stable fracture reductions may be splinted in the protected position, consisting of metacarpophalangeal flexion >70 degrees and interphalangeal joint extension to minimize joint stiffness (for positioning, ask the child to hold a cup for splinting).

• Percutaneous pinning may be necessary to obtain stable reduction; if possible, the metaphyseal component (Thurston-Holland fragment) should be included in the fixation.

Early range of motion is essential.

Type B: Metacarpal Neck

Fractures of the fourth and fifth metacarpal necks are commonly seen as pediatric analogs to boxer’s fractures in adults.

The degree of acceptable deformity varies according to the metacarpal injured, especially in adolescents:

• More than 15-degree angulation for the second and third metacarpals is unacceptable.

• More than 40- to 45-degree angulation for the fourth and fifth metacarpals is unacceptable.

These are typically addressed by closed reduction using the Jahss maneuver by flexing the metacarpophalangeal joint to 90 degrees and placing an axial load through the proximal phalanx. This is followed by splinting in the protected position.

Unstable fractures require operative intervention with either percutaneous pins (may be intramedullary or transverse into the adjacent metacarpal) or plate fixation (adolescents).

Type C: Metacarpal Shaft

Most of these fractures may be reduced by closed means and splinted in the protected position.

Operative indications include unstable fractures, rotational deformity, dorsal angulation >10 degrees for second and third metacarpals, and >20 degrees for fourth and fifth metacarpals, especially for older children and adolescents in whom significant remodeling is not expected.

Operative fixation may be achieved with closed reduction and percutaneous pinning (intramedullary or transverse into the adjacent metacarpal). Open reduction is rarely indicated, although the child presenting with multiple, adjacent, displaced metacarpal fractures may require reduction by open means.

Type D: Metacarpal Base

The carpometacarpal joint is protected from frequent injury owing to its proximal location in the hand and the stability afforded by the bony congruence and soft tissue restraints.

The fourth and fifth carpometacarpal joints are more mobile than the second and third; therefore, injury to these joints is uncommon and usually results from high-energy mechanisms.

Axial loading from punching mechanisms typically results in stable buckle fractures in the metaphyseal region.

Closed reduction using regional or conscious sedation and splinting with a short arm ulnar gutter splint may be performed for the majority of these fractures, leaving the proximal interphalangeal joint mobile.

Fracture-dislocations in this region may result from crush mechanisms or falls from a height; these may initially be addressed with attempted closed reduction, although transverse metacarpal pinning is usually necessary for stability. Open reduction may be necessary, especially in cases of multiple fracture-dislocations at the carpometacarpal level.

Thumb Metacarpal

Fractures are uncommon and are typically related to direct trauma.

Metaphyseal and physeal injuries are the most common fracture patterns.

Structures inserting on the thumb metacarpal constitute potential deforming forces:

• Opponens pollicis: Broad insertion over metacarpal shaft and base that displaces the distal fragment into relative adduction and flexion

• Abductor pollicis longus: Multiple sites of insertion including the metacarpal base, resulting in

  abduction moment in cases of fracture-dislocation

• Flexor pollicis brevis: Partial origin on the medial metacarpal base, resulting in flexion and apex dorsal angulation in metacarpal shaft fractures

• Adductor pollicis: Possible adduction of the distal fragment

  Thumb Metacarpal Head and Shaft Fractures

These typically result from direct trauma.

Closed reduction is usually adequate for the treatment of most fractures, with postreduction immobilization consisting of a thumb spica splint or cast.

Anatomic reduction is essential for intra-articular fractures and may necessitate the use of percutaneous pinning with Kirschner wires.

Thumb Metacarpal Base Fractures

These are subclassified as follows (Fig. 46.4):

Type A: Fractures distal to the physis

• They are often transverse or oblique, with apex-lateral angulation and an element of medial impaction.

• They are treated with closed reduction with extension applied to the metacarpal head and direct

  pressure on the apex of the fracture, and then immobilized in a thumb spica splint or cast for 4 to 6 weeks.

• Up to 30 degrees of residual angulation may be accepted in younger children.

• Unstable fractures may require percutaneous Kirschner wire fixation, often with smooth pins to

  cross the physis. Transcarpometacarpal pinning may be performed but is usually reserved for more proximal fracture patterns.

Type B: Salter-Harris type II fracture, metaphyseal medial

• The shaft fragment is typically angulated laterally and displaced proximally owing to the pull of the abductor pollicis longus; adduction of the distal fragment is common because of the pull of the adductor pollicis.

• Anatomic reduction is essential to avoid growth disturbance.

• Closed reduction followed by thumb spica splinting is initially indicated, with close serial follow-up. With maintenance of reduction, immobilization should be continued for 4 to 6 weeks.

• Percutaneous pinning is indicated for unstable fractures with capture of the metaphyseal

  fragment if possible. Alternatively, transmetacarpal pinning to the second metacarpal may be necessary. Open reduction may be required for anatomic restoration of the physis.

Type C: Salter-Harris type II fracture, metaphyseal lateral

• These are similar to type B fractures, but they are less common and typically result from more significant trauma, with consequent apex medial angulation.

• Periosteal buttonholing is common and may prevent anatomic reduction.

• Open reduction is frequently necessary for restoration of anatomic relationships.

Type D: Intra-articular Salter-Harris type III or IV fractures

• These are the pediatric analogs to the adult Bennett fracture.

• They are rare, with deforming forces similar to type B fractures, with the addition of lateral subluxation at the level of the carpometacarpal articulation caused by the intra-articular component of the fracture.

• Nonoperative methods of treatment widely variable in results. Most consistent results are obtained with open reduction and percutaneous pinning or internal fixation in older children.

• Severe comminution or soft tissue injury may be initially addressed with oblique skeletal

  traction.

• External fixation may be used for contaminated open fractures with potential bone loss.

  Phalanges (Fig. 46.5)

   

   

   

The physes are located at the proximal aspect of the phalanges.

The collateral ligaments of the proximal and distal interphalangeal joints originate from the collateral recesses of the proximal bone and insert onto both the epiphysis and metaphysis of the distal bone and volar plate.

The volar plate originates from the metaphyseal region of the phalangeal neck and inserts onto the epiphysis of the more distal phalanx.

The extensor tendons insert onto the dorsal aspect of the epiphysis of the middle and distal phalanges.

The periosteum is typically well developed and exuberant, often resisting displacement and aiding reduction, but occasionally interposing at the fracture site and preventing adequate reduction.

Proximal and Middle Phalanges

Pediatric fractures of the proximal and middle phalanges are subclassified as follows:

Type A: Physeal

• Of pediatric hand fractures, 41% involve the physis. The proximal phalanx is the most frequently injured bone in the pediatric population.

• The collateral ligaments insert onto the epiphysis of the proximal phalanx; in addition to the

  relatively unprotected position of the physis at this level, this contributes to the high incidence of physeal injuries.

• A pediatric gamekeeper’s thumb is a Salter-Harris type III avulsion fracture, with the ulnar collateral ligament attached to an epiphyseal fragment of the proximal aspect of the proximal phalanx.

• Initial treatment is closed reduction and splinting in the protected position.

• Unstable fractures may require percutaneous pinning. Fractures with >25% articular involvement or >1.5-mm displacement require open reduction with internal fixation with Kirschner wires or screws.

Type B: Shaft

• Shaft fractures are not as common as those surrounding the joints.

• Proximal phalangeal shaft fractures are typically associated with apex volar angulation and displacement, created by forces of the distally inserting central slip and lateral bands coursing dorsal to the apex of rotation, as well as the action of the intrinsics on the proximal fragment pulling it into flexion.

• Oblique fractures may be associated with shortening and rotational displacement. This must be recognized and taken into consideration for treatment.

• Closed reduction with immobilization in the protected position for 3 to 4 weeks is indicated for

  the majority of these fractures.

• Residual angulation >30 degrees in children <10 years of age, >20 degrees in children >10 years of age, or any malrotation requires operative intervention, consisting of closed reduction and percutaneous crossed pinning. Intramedullary pinning may allow rotational displacement.

Type C: Neck (Fig. 46.6)

• Fractures through the metaphyseal region of the phalanx are commonly associated with door-slamming injuries.

• Rotational displacement and angulation of the distal fragment are common, because the

  collateral ligaments typically remain attached distal to the fracture site. This may allow interposition of the volar plate at the fracture.

• Closed reduction followed by splinting in the protected position for 3 to 4 weeks may be attempted initially, although closed reduction with percutaneous crossed pinning is usually required.

   

   

   

Type D: Intra-articular (condylar)

• These arise from a variety of mechanisms, ranging from shear or avulsion resulting in simple fractures to combined axial and rotational forces that may result in comminuted, intra-articular T- or Y-type patterns.

• Open reduction and internal fixation are usually required for anatomic restoration of the articular surface. This operation is most often performed through a lateral or dorsal incision, with fixation using Kirschner wires or miniscrews.

  Distal Phalanx

These injuries are frequently associated with soft tissue or nail compromise and may require subungual hematoma evacuation, soft tissue reconstructive procedures, or nail bed repair.

Pediatric distal phalangeal fractures are subclassified as follows:

• Physeal

  • Dorsal mallet injuries (Fig. 46.7)

    Type A: Salter-Harris type I or II injuries

    Type B: Salter-Harris type III or IV injuries

    Type C: Salter-Harris type I or II associated with joint dislocation

    Type D: Salter-Harris fracture associated with extensor tendon avulsion

     

     

     

• A mallet finger may result from a fracture of the dorsal lip with disruption of the extensor tendon. Alternatively, a mallet finger may result from a purely tendinous disruption and may therefore not be radiographically apparent.

• Treatment of type A and nondisplaced or minimally displaced type B injuries is full-time extension splinting for 4 to 6 weeks.

• Types C, D, and displaced type B injuries typically require operative management. Type B

  injuries are usually amenable to Kirschner wire fixation with smooth pins. Types C and D injuries generally require open reduction and internal fixation.

Volar (reverse) mallet injuries

• These are associated with flexor digitorum profundus rupture (jersey finger: seen in football and rugby players, most commonly involving the ring finger).

• Treatment is primary repair using heavy suture, miniscrews, or Kirschner wires. Postoperative

  immobilization is continued for 3 weeks.

Extraphyseal

Type A: Transverse diaphyseal Type B: Longitudinal splitting Type C: Comminuted

• The mechanism of injury is almost always direct trauma.

• Nail bed injuries must be recognized and addressed.

• Treatment is typically closed reduction and splinting for 3 to 4 weeks with attention to concomitant injuries. Unstable injuries may require percutaneous pinning, either longitudinally from the distal margin of the distal phalanx or across the distal interphalangeal joint

  (uncommon) for extremely unstable or comminuted fractures.

  Complications

Impaired nail growth: Failure to repair the nail bed 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 can also 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.