Forearm Fractures - Pediatric

Structural Considerations

The forearm is a functional unit:

• Radius and ulna connected by proximal and distal radioulnar joints
• Interosseous membrane provides stability
• Rotation occurs through supination/pronation
• Neutral rotation: thumb up, radial bow lateral

Radial bow significance: The natural radial bow allows clearance for muscle bellies and is essential for full pronation-supination. Loss of radial bow restricts rotation.

Deforming Forces

Proximal fractures (above pronator teres):

• Proximal fragment supinated by biceps and supinator
• Distal fragment pronated by pronator teres
• Reduce in supination

Mid-shaft fractures (below pronator teres):

• Proximal and distal fragments both have pronation/supination forces
• Reduce in neutral

Distal fractures: Reduce in pronation (most common reduction position).

Pediatric Forearm Fracture Patterns

Bado Classification of Monteggia

Type I (extension injury) is by far the most common in children.

Galeazzi Fracture-Dislocation

Radius fracture with DRUJ disruption:

• Less common in children than adults
• Distal radius fracture (typically distal third)
• DRUJ subluxation or dislocation
• Often more stable in children (intact periosteum)

Management: Reduce radius fracture. DRUJ usually reduces spontaneously in children. Above elbow cast in supination.

Radiological Investigations

Key principle: The joint above and below a forearm fracture must be imaged.

Measuring Angulation

On AP view: Measure coronal plane angulation (apex medial or lateral). Less forgiving to residual deformity.

On lateral view: Measure sagittal plane angulation (apex anterior or posterior). Better remodeling in this plane.

Radial bow: Compare to opposite side if concerned about loss of radial bow.

Buckle (Torus) Fracture Management

Definition: Stable cortical compression injury without displacement.

Treatment: Splint or removable cast for 3-4 weeks. Parent-directed removal is safe. No follow-up X-rays usually needed.

Key points: These are inherently stable. Do not overtreatthem with above elbow casts. Early mobilization is safe.

Greenstick Fracture Management

Less than 10° angulation: Below elbow cast, serial X-rays as can re-angulate.

Greater than 15-20° angulation:

• Complete the fracture (break intact cortex) under sedation or GA
• This allows full reduction without spring-back
• Apply above elbow cast with proper 3-point mold
• Close follow-up for first 2 weeks (loss of reduction common)

Warning: Incomplete reduction leads to cast loosening and re-angulation.

Complete Both-Bone Fracture Management

Closed reduction technique:

• Finger trap traction or manual traction
• Correct length, then rotation, then angulation
• Above elbow cast with well-molded interosseous space
• Post-reduction X-rays to confirm alignment

Cast position:

• Proximal fracture: forearm supinated
• Mid-shaft: forearm neutral
• Distal: forearm pronated

Acceptable position: Length re-established, less than 10° angulation (over 10 years), rotation anatomic.

Elastic Stable Intramedullary Nailing

Indications for ESIN:

• Unacceptable reduction after closed attempt
• Re-displacement in cast
• Open fracture
• Polytrauma
• Older child/adolescent with unstable pattern
• Segmental fractures

Technique: Retrograde radius (above Lister's or lateral), antegrade ulna (olecranon or metadistance). Pre-bend nails, avoid physis. Remove at 6-12 months.

ESIN for Pediatric Forearm Fractures

Radius entry:

• Dorsal entry just proximal to Lister's tubercle OR
• Lateral entry above distal radial physis
• Avoid palmar entry (flexor tendons)

Ulna entry:

• Proximal/antegrade entry at olecranon or proximal metadiaphysis
• Avoid distal ulnar physis (small, subcutaneous)

Technical pearls: Pre-bend nails for radial bow. Seat nails well to avoid irritation and protrusion. Both bones should ideally be nailed. Use 2-2.5mm nails typically.

When Open Reduction is Needed

Indications:

• Failed closed reduction
• Open fracture
• Associated vascular injury
• Irreducible Monteggia
• Late presentation Monteggia

Approach: Henry (anterior) for radius, direct subcutaneous for ulna. Preserve periosteum. Avoid extensive stripping.

Monteggia Fracture-Dislocation

The triad: Ulna fracture + radial head dislocation + disrupted annular ligament.

Bado Type I (most common in children): Apex anterior ulna angulation, anterior radial head dislocation. Extension injury mechanism.

Treatment: Closed reduction of ulna usually reduces radial head. Above elbow cast in flexion and supination. If radial head remains dislocated, open reduction may be needed (annular ligament may be entrapped). Check radiocapitellar line post-reduction.

Plastic Deformation

Unique to pediatric bone: Bowing of bone without visible fracture line. Causes restricted rotation if significant.

Treatment:

• Less than 10° bow: Accept
• 10-20° bow: Consider reduction
• Greater than 20° bow: Requires reduction under GA with sustained force

Technique: Sustained pressure over apex of deformity for 2-3 minutes. Bone slowly straightens. Cannot "snap" it - must bend gradually.

Refracture Prevention

Risk factors for refracture:

• Early return to full activity
• Removal of cast too early
• Initial cortical comminution
• Stress risers from previous fracture

Prevention: Continue protective splinting for sport for 6 months. Avoid high-risk activities. Some surgeons do not recommend specific protection; counsel family about risk.