Courtesy: Kaye WIlkins MD
Lynn Staheli MD

Terminology

Preferred terminology

• Fracture of the shaft (diaphysis) of the radius and or ulna.
• Avoid the vague term “both bone forearm fracture.”

Epidemiology

Age distribution

• Boys commonly sustain injuries at 9 to 10 years due to playground activities.
• A second peak occurs at 14 to 15 years due to sports injuries.
• Girls traditionally have an earlier peak, although this is changing with increased sports participation.

Anatomical Distribution

Location of fractures

• Metaphyseal fractures account for approximately 52 percent.
• Distal physeal and metaphyseal fractures account for approximately 70 percent.
• Shaft fractures account for approximately 25 percent.
• Proximal fractures account for approximately 6 percent.

Distribution within shaft fractures

• Proximal third: Approximately 9 percent.
• Middle third: Approximately 30 percent.
• Distal third: Approximately 57 percent.

Reasons distal shaft fractures are more common

• Weaker metaphyseal transition zone.
• Less muscle protection.
• Longer lever arm.

Muscle Forces and Deforming Forces

Proximal fragment

• Biceps produces flexion and supination.
• Supinator produces supination and external rotation.

Distal fragment

• Pronator teres and pronator quadratus produce pronation.
• Brachioradialis causes shortening and angulation.

Clinical importance

• Muscle forces create rotational malalignment after fracture.

Classification

Based on fracture level

• Proximal third.
• Middle third.
• Distal third.

Based on fracture completeness

• Plastic deformation.
• Greenstick fracture.
• Complete fracture.

Based on deformity

• Angulation.
• Rotation.

Types of Fractures

Plastic deformation

• No cortical break.
• Permanent bending due to internal structural failure.
• Presents with forearm deformity and loss of pronation and supination.
• Pain may be minimal.

Greenstick fracture

• Tension cortex is fractured.
• Compression cortex remains intact.
• Most commonly presents with supination and apex volar deformity.
• Less commonly presents with pronation and apex dorsal deformity.
• Both rotational and angular deformities must be corrected.

Complete fracture

• Both cortices are disrupted.
• Associated with shortening, angulation, and rotational deformity.

Principles of Reduction

General principle

• Correct rotational deformity first.
• Correction of angulation often follows automatically.

Reduction according to deformity

• Supination with apex volar deformity: Pronate the forearm.
• Pronation with apex dorsal deformity: Supinate the forearm.

Treatment

Plastic deformation

• Gradual sustained pressure over a fulcrum.
• Goal is restoration of forearm rotation rather than perfect radiographs.
• Immobilize for approximately 6 weeks.

Greenstick fracture

• Closed reduction followed by casting.
• Completion of the fracture remains controversial.
• Completing the fracture may improve callus formation and reduce refracture risk.
• It may also increase instability and hematoma formation.

Complete fracture

• Closed reduction and casting if acceptable alignment is achieved.

Principles of Casting

• Long arm cast is usually preferred.
• Cast position should be determined by the fracture pattern rather than the fracture level.

Older teaching

• Distal fractures in pronation.
• Midshaft fractures in neutral.
• Proximal fractures in supination.

Current concept

• Cast according to the deformity and reduction achieved.

Cast in extension (Rang technique)

• Useful when there is a high risk of redisplacement.
• May be used after remanipulation.
• Include the thumb to prevent cast slippage.

Acceptable Reduction (Price Criteria)

Children younger than 9 years

• Angulation up to 15 degrees.
• Rotation up to 45 degrees.

Children older than 9 years

• Angulation up to 10 degrees.
• Rotation up to 30 degrees.

Shortening

• Less than 1 cm is acceptable.

Indications for Surgery

• Open fractures.
• Compartment syndrome.
• Failure of closed reduction.
• Inability to maintain reduction.
• Ipsilateral injuries such as floating elbow.
• Refractures.
• Severe soft tissue injury.

Surgical Options

Intramedullary nailing

• Preferred method using elastic nails or Kirschner wires.
• Causes minimal soft tissue damage.
• Shorter operative time.
• Easier implant removal.

Plate fixation

• Useful in selected fractures.

External fixation

• Reserved for severe soft tissue injury or complex trauma.

Special Situations

Refracture

• Occurs in approximately 10 percent.
• Risk factors include early return to activity, greenstick fractures, and residual deformity.
• Often treated with intramedullary nailing.

Floating elbow

• Fix the forearm fracture first to improve leverage during reduction.

Rotational malalignment

• Compare the radial tuberosity with the radial styloid.
• Normal relationship is approximately 180 degrees.
• Rotational deformity is commonly overlooked.

Complications

• Loss of reduction.
• Malunion.
• Refracture.
• Radioulnar synostosis.
• Compartment syndrome.
• Nerve injury.

Exam Pearls

• Rotational alignment is more important than angular alignment.
• The proximal fragment is the “king fragment” because it determines reduction.
• Greenstick fractures have both rotational and angular deformities.
• Plastic deformation is easily missed.
• Diaphyseal fractures have less remodeling potential than distal forearm fractures.