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