Executive Editor: James Hunter General Editor: Fergal Monsell

Authors: Andrew Howard, Peter Schmittenbecher, Theddy Slongo

Pediatric forearm shaft 22u-D/4.1

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1 Principles top

Pediatric considerations

Reduction and casting of displaced fractures is performed with conscious sedation or general anesthesia in children.

The environment should be one in which the child and the parents/carers are comfortable.

Important considerations include:

  • A child-sensitive approach
  • A child-friendly clinical area
  • Careful explanation of the procedure, in language that is understood by the child and the parents/carers
  • Availability of all equipment and material

A provider familiar with pediatric sedation and airway management should take responsibility for the safety of the anesthetic.

Forearm diaphyseal fractures require a long arm cast to control forearm rotation. enlarge

General considerations

Forearm diaphyseal fractures require a long arm cast to control forearm rotation and therefore decrease the risk of displacement.

Correct molding of the cast helps to prevent redisplacement of the fracture.

If a complete cast is applied in the acute phase after injury, it is safer to split the cast down to skin over its full length.

Periosteum as a factor in fracture stability enlarge

Periosteum as a factor in fracture stability

Children’s periosteum is a thick, tough tissue and is often intact on the concave (compression) side of a fracture.

This confers extra stability with three-point molding as the concave side periosteum acts as a tension band.

Cast versus splint

A splint may be preferred to a cast in three situations:

  • Stable injuries with no risk of displacement
  • Injuries with a greater degree of soft-tissue swelling
  • Temporary immobilization before operative fixation


  • Potentially lower risk of compartment syndrome
  • No need for cast-saw removal


  • Less stability
  • Difficult or impossible to provide effective molding

2 Preparation for cast application top

Equipment enlarge


  • Examination couch
  • Tubular bandage (40-80 mm wide, depending on the size of the child)
  • 2-4 rolls of padding (40-150 mm wide, depending on the size of the child)
  • 2-8 plaster of Paris (POP) or synthetic fiberglass bandages (40-150 mm wide, depending on the size of the child)
  • Malleable (thermoplastic, leather, or lead) strip
  • Bucket with cold water
  • Protective aprons for the team members and the child
  • Appropriate equipment to cut, split, or remove the cast
  • Finger traps and a pole to suspend them
  • C-arm if available

Finger traps enlarge

Finger traps

Convenient OR setup for single surgeon work is illustrated here.

Holding the arm using finger traps as illustrated allows easy manipulation, reduction, imaging, and mobilization for a surgeon working without an assistant.

To avoid damage to the skin of the fingers ensure that the pressure is evenly distributed, and that prolonged or excessive force is avoided.

3 Closed reduction top

22u-D4.1 enlarge

General considerations

Closed manipulation of the ulna can be difficult in the presence of an intact radius.

Always exclude a radial head dislocation (Monteggia lesion).

Reduction maneuvers enlarge

Reduction maneuvers

With the arm in finger traps grasp the elbow epicondyles to stabilize the proximal fragment and grasp the distal ulna to provide longitudinal traction and simultaneous reduction of angular and rotational displacements.

Reduction maneuvers enlarge

Direct thumb pressure on the apex of the ulnar deformity may help.

Evaluation of reduction

Evaluate the reduction by C-arm if available with the arm in different positions of rotation.

Position the arm in a neutral rotation or supination depending on the best alignment of the fracture.

Adjust the reduction if necessary.

4 Cast application top

Arm position enlarge

Arm position

Flex the elbow to 90° prior to application of the tubular bandage and padding, to avoid compression at the antecubital fossa.

Place the forearm in neutral rotation for undisplaced, stable fractures.

Preparation for splitting the cast enlarge

Preparation for splitting the cast

A temporary malleable (thermoplastic, leather, or lead) strip can be placed beneath the tubular bandage, prior to plaster application, to protect the skin when plaster splitting is required.

The location of the strip should be planned to avoid areas of molding.

Application of tubular bandage enlarge

Application of tubular bandage

Apply a tubular bandage directly onto the skin and malleable strip, from the axillary crease to just distal to the MCP joints allowing sufficient bandage for protection of the cast edges.

Application of tubular bandage enlarge

Cut a hole for the thumb.

Application of padding enlarge

Application of padding

Apply a single layer of padding from the MCP joints of the fingers and thumb to the axillary crease.

Overlap each layer by 1/2.

Apply extra padding over pressure areas, including the olecranon.

Take care not to constrict the antecubital fossa.

The tubular bandage and padding should be applied without creases.

Application of padding enlarge

Consistent firm but not tight wrapping should result in a neat stable layer of padding that does not constrict the arm.

Application of plaster enlarge

Application of plaster

Immerse the POP/fiberglass bandage for 5-10 seconds and then remove excess water by gentle squeezing.

Apply a first layer of circumferential POP/fiberglass.

The plaster extends distally to the metacarpal heads and palmar flexor crease and proximally to just distal to the axillary crease.

Trim excess plaster to accommodate the thumb and fingers.

Application of plaster enlarge

Apply a slab the width of the forearm over the ulnar aspect and the posterior humerus.

Completion of plaster cast enlarge

Completion of plaster cast

Fold the proximal and distal ends of the tubular bandage over the cast and cover the cast with an additional single layer of POP/fiberglass bandage.

Ensure that the edges of the cast are well-padded and smooth, to avoid abrasion during the period of plaster immobilization.

Molding the cast enlarge

Molding the cast

Even for an undisplaced fracture the cast should be molded to an oval cross-section to match the shape of the forearm.

Molding the cast enlarge

To prevent displacement, ensure that the ulnar border of the cast is straight (A) or molded to provide a three-point fixation (B), against the anticipated direction of displacement.

The assistant should support the limb until the cast is hardened.

5 Final assessment top

X-ray confirmation of reduction

Take an x-ray in both AP and lateral view.

X-ray evaluation of the cast enlarge

X-ray evaluation of the cast

An x-ray of a well applied forearm cast will show:

  • A cast index of 0.7 or less (width on lateral view/width on AP view; CI = A/B)
  • Correctly applied three-point molding
  • Straight ulnar border
  • Dense material where the mold has been applied, but no bumps or wrinkles

Compartment syndrome enlarge

Compartment syndrome

The ability to fully extend the fingers passively, or actively, without discomfort indicates absence of muscle compartment ischemia.

Flexion of MCP joints enlarge

Flexion of MCP joints

Care should be taken to ensure that the plaster cast does not restrict flexion of the MCP joints.

Sling enlarge


The arm is supported in a broad arm sling.

6 Cast splitting top

Cast splitting enlarge

When required, the plaster should be split along the entire length.

Once the cast is hardened, mark it, then split using an oscillating saw, a hand saw, or a sharp plaster knife (1).

Take great care to avoid injury to the underlying skin.

Widen the split with a cast spreader. Then divide the underlying padding with scissors (2) and remove the protective strip to expose the skin.

Apply a crêpe bandage to protect the split cast.

When the swelling has subsided (after 5-7 days), complete the cast with a single POP bandage.

7 Splint application top

Application of cast padding enlarge

Application of cast padding

Wrap cast padding around the upper arm, elbow, forearm and hand, as far as the transverse flexor crease of the palm (the MP joints are left free). According to surgeon’s preference a tubular bandage may be applied to the arm beneath the padding.

Hold the elbow in 90° flexion and the forearm in neutral rotation.

Make sure that the epicondyles of the humerus and the antecubital area are well padded.

Application of splint enlarge

Application of splint

Apply a splint of fiberglass, or plaster, on the posterior aspect of the arm and forearm. It should be wide enough to cover more than half the circumference of the arm and forearm.

Application of splint enlarge

Secure the splint with a noncompressive bandage.

Ensure that this is not tight, to accommodate subsequent swelling.

Sling enlarge


The injured arm and splint are supported with a sling.

v1.0 2018-11-28