Forearm Fracture

In adults, a diaphyseal fracture of both radius and ulna should be treated functionally as an articular injury, because rotation of the forearm depends on precise restoration of the relationship between both bones.

Even modest malalignment can substantially reduce pronation and supination.

The major objectives are:

• Restore length
• Restore rotation
• Restore radial bow
• Restore the proximal radioulnar joint
• Restore the distal radioulnar joint
• Preserve interosseous space

AO morphology

Adult forearm shaft injuries are broadly classified as:

Simple

• Spiral
• Oblique
• Transverse

Wedge

• Spiral wedge
• Bending wedge
• Fragmented wedge

Multifragmentary

• Complex spiral
• Segmental
• Irregular comminution

Each bone should be described separately because the radius and ulna can have different fracture morphology.

Monteggia fracture dislocation

An ulnar fracture associated with radial head dislocation.

Bado I

Anterior radial head dislocation with anterior angulation of the ulna.

Most common in children.

Bado II

Posterior or posterolateral radial head dislocation with posterior ulnar angulation.

Common adult pattern.

Bado III

Lateral radial head dislocation with proximal ulnar metaphyseal fracture.

Bado IV

Fractures of both radius and ulna with radial head dislocation.

The key operative principle is restoration of ulnar length and alignment, which often reduces the radial head automatically.

Galeazzi fracture

Fracture of the distal third of the radial shaft with disruption of the distal radioulnar joint.

In adults, this is an operative injury.

DRUJ instability is assessed after anatomical radial fixation.

Both bone forearm fractures usually produce obvious deformity, pain and swelling.

Inspect for open wounds.

Document:

• Radial pulse
• Ulnar pulse
• Median nerve
• Anterior interosseous nerve
• Ulnar nerve
• Radial nerve
• Posterior interosseous nerve

Assess both elbow and wrist.

Look specifically for:

• Radial head dislocation
• DRUJ tenderness or instability
• Compartment syndrome

Forearm compartment syndrome can threaten hand function rapidly.

Pain with passive finger stretch, increasing tension and escalating analgesia should prompt immediate reassessment.

Obtain AP and lateral radiographs of the entire forearm including elbow and wrist.

Do not accept a cropped image of only the shaft because Monteggia and Galeazzi injuries can be missed.

CT is usually unnecessary for a straightforward shaft fracture but may be helpful with complex periarticular extension.

Adults with both bone shaft fracture

Most displaced adult both bone forearm fractures require open reduction and internal fixation of both bones.

Nonoperative treatment is generally reserved for:

• Truly nondisplaced fractures
• Exceptional patients unable to undergo surgery

ORIF principles

Anatomical reconstruction is more important than in many other diaphyseal fractures.

Restore the normal radial bow.

Loss of radial bow reduces pronation and supination even if both fractures unite.

Standard fixation generally uses 3.5 mm compression plates.

For simple fractures:

• Obtain anatomical reduction
• Apply interfragmentary compression where appropriate
• Use compression plating

For comminuted fractures:

• Preserve soft tissue attachment
• Restore length, alignment and rotation
• Bridge comminution rather than stripping fragments to obtain anatomical reconstruction

At least approximately three bicortical screws proximal and distal to each fracture are commonly used for conventional plate fixation.

Do not close the deep forearm fascia under excessive tension after major swelling because this can contribute to compartment pressure.

Isolated ulnar shaft fracture

A stable isolated low energy ulnar shaft fracture with limited displacement can be treated nonoperatively.

Operate for:

• Significant displacement
• Angulation
• Open fracture
• Proximal injury associated with radial head instability

Monteggia injury

Perform anatomical plate fixation of the ulna.

After ulnar reduction, confirm radiocapitellar alignment through the full elbow range.

If the radial head remains dislocated after correct ulnar reconstruction:

• Look for annular ligament interposition
• Reassess ulnar length and angulation
• Perform open radial head reduction when necessary

Galeazzi injury

Perform anatomical fixation of the radius.

Then assess the DRUJ in:

• Neutral
• Pronation
• Supination

A stable DRUJ requires no additional fixation.

If unstable:

• Reduce the DRUJ
• Repair an incarcerated triangular fibrocartilage complex when necessary
• Temporarily pin the DRUJ in the position of maximal stability when instability persists

Compartment syndrome

Emergency fasciotomy is required for established acute compartment syndrome.

Decompress both:

• Volar compartment
• Dorsal mobile wad and dorsal compartment where required

Carpal tunnel release may be added when significant median nerve compression exists.

Rehabilitation

Stable plate fixation generally permits early elbow, wrist and forearm movement.

Avoid heavy loading until union.

Major complications include:

• Loss of pronation and supination
• Nonunion
• Infection
• Synostosis between radius and ulna
• Compartment syndrome
• DRUJ instability
• Radial head instability
• Refracture after premature plate removal

Routine plate removal is not indicated in asymptomatic adults because refracture can occur after removal.