Distal Radius Fractures - Pediatric - Pediatrics

Introduction

Epidemiology
- incidence
  - common - forearm fractures in total account for approximately 40% of all pediatric long bone fractures
  - distal radius (and ulna) is the most common site of pediatric forearm fractures.
  - male > female (male 2-3 times more common than female)
- demographics
  - most common during metaphyseal growth spurt
  - peak incidence occurring from:
    - 10-12 years of age in girls
    - 12-14 years of age in boys
  - most common fracture in children under 16 years old
Pathophysiology
- mechanism
  - usually fall on an outstretched hand, extended at wrist
  - often during sports or play
- remodeling
  - greatest closer to physis and in plane of joint (wrist) motion
    - sagittal plane (flexion/extension)
  - least for rotational deformity

Anatomy

Distal radius physis
- contributes 75% growth of the radius
- contributes 40% of entire upper extremity
- growth at a rate of ~ 5.25mm per year
Metaphyseal fracture most common, followed by physeal

Classification

Relation to distal physis
- Physeal considerations
- Salter-Harris I
- Salter-Harris II
- Salter-Harris III
- Salter-Harris IV
- Salter-Harris V
Metaphysis (distal) (62%)
- complete (Distal Radius fracture)
  - apex volar (Colles' fracture)
  - apex dorsal (Smith's fracture)
- incomplete (Torus/Buckle fracture)
  - unicortical, non-displaced
Diaphysis (20%)
- both bone forearm fracture
- isolated radial shaft fracture
- isolated ulnar shaft fracture
- plastic deformation
  - deforming force over time resulting in shape change of bone without clear fracture line
  - thought to be due to a large number of microfractures resulting from a relatively lower force over longer time compared to mechanism for complete fractures
- greenstick fracture
  - incomplete fracture resulting from failure along tension (convex) side
    - typically plastic deformation occurs along compression side
Fracture with dislocation / associated injuries
- Monteggia fracture
  - ulnar shaft fracture with radiocapitellar dislocation
- Galeazzi fracture
  - radius fracture (typically distal 1/3) with associated DRUJ injury, often dislocation

Presentation

History
- wide range of mechanisms for children, often fall during play or other activity, outstretched hand
- rule out child abuse
  - mechanism or history appears inconsistent with injury
  - multiple injuries, especially different ages
  - child's affect
  - grip marks/ecchymosis
Symptoms
- pain, swelling, and deformity
Physical exam
- gross deformity may or may not be present
- ecchymosis and swelling
- inspect for puncture wounds suggesting open fracture
- although uncommon, compartment syndrome and neurovascular injury should be evaluated for in all forearm fractures.

Imaging

Radiographs
- recommended views
  - AP and lateral of wrist
  - AP and lateral of forearm
  - AP and lateral of elbow if tender about elbow, or diaphyseal fractures present
- findings
  - in addition to fracture must evaluate for associated injuries
    - scapholunate interval
    - DRUJ (distal radio-ulnar joint)
    - ulnar styloid
    - elbow injuries
CT scan
- indications
  - useful to characterize fracture if intra-articular
  - use sparingly in children given concerns of increased longitudinal effects of radiation

Treatment

"Classically" Acceptable Angulation for Closed Reduction in Pediatric Forearm Radius Fractures (controversial with ongoing discussion)
	Shaft / Both bone fx			Distal radius/ulna
Age	Acceptable Bayonetting	Acceptable Angulations	Malrotation*	Dorsal Angulation
< 9 yrs	< 1 cm	15-20°	45°	30 degrees
> 9 yrs.	< 1 cm	10°	30°	20 degrees
Bayonette apposition, or overlapping, of less than 1 cm, does not block rotation and is acceptable in patients less than 10 years of age. General guidelines are that deformities in the plane of joint motion are more acceptable, and distal deformity (closer to distal physis) more acceptable than mid shaft. The radius and ulna function as a single rotational unit. Therefore a final angulation of 10 degrees in the diaphysis can block 20-30 degrees of rotation. Rotational deformities do not remodel and are increasingly being considered as not* acceptable.

Nonoperative
- immobilization in short arm cast for 2-3 weeks without reduction
  - indications
    - unicortical or bicortical fracture with < 10 deg of angulation
    - torus/buckle fracture
      - ongoing shift towards treating buckle fractures with pre-fabricated removable wrist splint, no cast, and limited follow-up
- closed reduction under conscious sedation followed by casting
  - indications
    - > 10-20 degrees of angulation
    - Salter-Harris I with unacceptable alignment
    - Salter-Harris II with unacceptable alignment
  - technique (see below)
    - reduction technique determined by fracture pattern
  - acceptable criteria (see table above)
    - acceptable angulations are controversial in the orthopedic community
    - accepted angulation is defined on a case by case basis depending on
      - the age of the patient
      - location of the fracture
      - type of deformity (angulation, rotation, bayonetting)
  - outcomes
    - short-arm (SAC) vs long-arm casting (LAC)
      - good SAC (proper cast index = sagital/coronal widths close to 0.7 for good cast) considered equal to LAC for distal radius fractures
        
        conservative treatment though often utilizes LAC to reduce impact of variable cast technique/quality
      - no increased risk of loss of reduction with (good) short arm vs. long arm casting
    - cast index
      - loss of reduction is associated with poor cast index
  - follow-up
    - all forearm fractures serial radiographs should be taken every 1 to 2 weeks initially to ensure reduction is maintained.
    - if concern for physeal injury, must follow child at least until growth seen on radiographs to confirm no growth arrest
Operative
- closed reduction and percutaneous pinning (CRPP)
  - indications
    - unstable patterns unable to reduce initially, or with loss of reduction in cast at follow-up
    - Salter-Harris I or II fractures in the setting of neurovascular (NV) compromise
      - CRPP reduces need for tight casting in setting with increased concern for compartment syndrome
    - fractures unable to reduce in emergency department (ED) but successfully closed reduced under anesthesia in the operating room (OR) may be pinned for added stability
- open reduction and internal fixation
  - indications
    - displaced Salter-Harris III and IV fractures of the distal radial physis/epiphysis unable to be closed reduced
    - irreducible fracture closed
      - often periosteum or pronator quadratus block to reduction

Treatment Techniques

Closed Reduction
- timing
  - avoid delayed reduction of greater than 1 week after injury
  - for physeal injuries, generally limit to one attempt to reduce chance of growth arrest
- reduction technique
  - gentle steady pressure for physeal reduction
  - for complete metaphyseal fractures re-create deformity to unlock fragments, then use periosteal sleeve to aid reduction
  - traction can be counter-productive due to thick periosteum
Casting
- historically consisted of a long arm cast for 6 to 8 weeks with the possibility of conversion to a short arm cast after 2-4 weeks depending on the type of fracture and healing response.
- may cast for shorter periods, 3-4 weeks, depending on child's age and healing on imaging
- multiple high quality studies show fractures of distal third may be immobilized with a properly molded short arm cast.
- special case of fratured distal radius with intact ulna: extreme ulna deviation of wrist helps keep radius fracture out to length.
CRPP
- approach
  - avoid dorsal sensory branch of radial nerve, typically with small incision
- reduction
  - maintain closed reduction during pinning
- fixation
  - radial styloid pins
    - usually 1 or 2 radial styloid pins, entry just proximal to physis preferred
    - if stability demands transphyseal pin, smooth wires utilized
    - for intra-articular fractures, may pin distal to physis transversely across epiphysis
  - dorsal pins
    - may also utilize dorsal pin, especially to restore volar tilt
    - for DRUJ injuries, or severe fractures unable to stabilize with radial pins alone, pin across ulna and DRUJ
- postoperative considerations
  - follow-up in clinic for repeat imaging to assess healing and position
  - pin removal typically in clinic once callus formation verified on radiograph
    - may consider sedation or removal of pins in OR for children unable to tolerate in clinic
  - must immobilize radio-ulnar joints in long arm cast if stabilizing DRUJ
  - may supplement with external fixator for severe injuries

Complications

Casting Thermal Injury
- risk factors for thermal injury include:
  - dipping water temperature is > 24C (75F)
  - more than 8 layers of plaster are used
  - during cast setting, the arm is placed on a pillow. This decreases the dissipation of heat from the exothermic reaction
  - fiberglass is overwrapped over plaster
Cast Saw Injury
- if bivalving or univalving cast, must ensure proper technique to avoid injury
- extra caution if cutting cast while child is sedated or under anesthesia
- cool saw blade frequently to ensure not overheating
Loss of Reduction
- poor cast index, increased initial displacement, and incomplete reduction are all risk factors for loss of reduction
Malunion
- most common complication
Physeal arrest
- from initial injury or repeated/late reduction attempts
- isolated distal radial physeal arrest can lead to ulnocarpal impaction, TFCC injuries, DRUJ injury
- distal ulnar physis most often to arrest
Ulnocarpal impaction
- from continued growth of ulna after radial arrest
TFCC injuries
Neuropathy
- Median nerve most commonly affected
- Uncommon in children, but must examine for acute carpal tunnel syndrome