Executive Editor: James Hunter General Editor: Fergal Monsell

Authors: Andrew Howard, Peter Schmittenbecher, Theddy Slongo

Pediatric forearm shaft 22r-D/4.1

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Glossary

1 Note on illustrations top

Generic fracture patterns enlarge

Throughout this section generic fracture patterns are illustrated as:

A) Unreduced
B) Reduced
C) Reduced and provisionally stabilized
D) Definitively stabilized

2 Principles of modular external fixation top

Modular external fixator enlarge

Modular external fixator

The versatility of a modular external fixator is an advantage in the management of children’s fractures and can accommodate age specific variations in fracture biology and anatomy.

An external fixator may be used for definitive management of forearm fractures in children due to the short healing time.

Practical considerations are illustrated in detail in the Basic technique for application of modular external fixator in children.

Specific considerations for the forearm shaft are given below.


Other types of external fixator enlarge

Other types of external fixator

Alterative configurations are available and include monolateral or ring systems.

Disadvantages of these systems in children include:

  • Fixed distance of pin insertion defined by the clamp
  • Excessively stiff construct

Pin size in forearm fractures

External fixation is suitable for all ages, but the pin diameter must be appropriate to the size of the bone.

Pins with a thread diameter of 2.5-4.0 mm are suitable for forearm fractures and should be about 1/3 of the bone diameter.


Sequence of pin insertion

Determined by:

  • Fracture morphology
  • Personal preference

3 Frame construction on the radius top

Distal pin insertion enlarge

Distal pin insertion

In the distal 1/3 of the forearm, the pin is inserted via a dorsolateral incision with blunt dissection to bone. Pins are inserted under direct vision, using retractors to avoid the superficial branch of the radial nerve. The pin passes between the extensor pollicis longus (EPL) and the extensor carpi radialis or more laterally between extensor carpi radialis and the tendon of brachioradialis.


Distal pin insertion enlarge

Make an 8-10 mm skin incision over the site of pin insertion.

Use an artery clip for blunt dissection down to the bone protecting important anatomical structures.


Distal pin insertion enlarge

Insert the pin in the near cortex and through the center of the bone into the far cortex.

Take care not to advance the tip of the pin beyond the far cortex to avoid damage to adjacent neurovascular structures.

Pins should not be placed within 1 cm of the physis.


Proximal pin insertion enlarge

Proximal pin insertion

The most critical anatomical consideration in the proximal 1/3 of the radius is the position of the posterior interosseous nerve, a continuation of the deep branch of the radial nerve, which perforates the supinator.

The dissection for the pin must be distal to the radial tuberosity and pass between the extensor carpi ulnaris and the mobile wad, penetrating the supinator muscle near its ulnar insertion.


Proximal pin insertion enlarge

A longer incision and blunt dissection to the bone is recommended to avoid damage to the posterior interosseous nerve.

Make a 1-2 cm skin incision over the site of pin insertion.

Use an artery clip for blunt dissection down to the bone, protecting important anatomical structures with small retractors.

Depending on the length of the proximal fragment, the distal pin may be positioned distal to the insertion of the supinator. This pin should also be inserted under direct vision.


Proximal pin insertion enlarge

Insert the pin in the near cortex and through the center of the bone into the far cortex.

Take care not to advance the tip of the pin beyond the far cortex to avoid damage to adjacent neurovascular structures.

Pins should not be placed within 1 cm of the physis.

4 Assessment of forearm rotation top

Assessment of forearm rotation enlarge

Once the fracture is reduced and stabilized, the position may be checked with an image intensifier.

The rotation of the forearm is also assessed clinically. Pronation and supination may be limited by the injury and fixator configuration.

If there is important radiological malalignment or functional restriction, the external fixator may be adjusted.

v1.0 2018-11-28