Executive Editor: Chris Colton

Authors: Dominik Heim, Shai Luria, Rami Mosheiff, Yoram Weil

Forearm shaft 22-B1.3 External fixation

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Glossary

Author: Dankward Höntzsch

1 Note on illustrations top

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Throughout this treatment option illustrations of generic fracture patterns are shown, as four different types:

A) Unreduced fracture
B) Reduced fracture 
C) Fracture reduced and fixed provisionally 
D) Fracture fixed definitively

2 Principles of modular external fixation top

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The modular external fixator is optimal for temporary use. It is rapidly applied without need for intraoperative x-rays and can be adjusted later.

Details of external fixation are described in the basic technique for application of modular external fixator.

Specific considerations for the forearm shaft are given below.


In Monteggia fracture-dislocations, anatomical reduction and stable fixation of the ulna are mandatory, in order to ensure stable relocation of the radial head.

For details on the stabilization of a dislocated radial head see:

Radial head stabilization (Monteggia fracture-dislocation)

If stabilization is not possible a joint bridging fixator may be used.

3 Pin insertion (forearm shaft) top

Soft-tissue dissection

Blunt dissection is performed using an instrument such as a small artery clip. This should displace important anatomic structures, which may then be retracted with small Langenbeck retractors. It is important to be aware of the anatomic structures at each level so that care can be taken to avoid damaging them.

4 Frame construction on the ulna top

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Pin insertion

The posterior border of the ulna is subcutaneous, so this usually offers the best access.

The pin should be inserted in the first cortex and through the center of the bone into the far cortex. Care should be taken to avoid the tip of the pin protruding significantly through the far cortex to avoid damage to neurovascular structures.


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The proximal ulnar pins are inserted through the subcutaneous cortex of the posterior border of the ulna between the extensor and flexor muscle masses.


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The distal ulnar pins are inserted through the posteromedial cortex.


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The subcutaneous posteromedial cortex is most safely accessible with the forearm in supination.

5 Assessment of Distal Radioulnar Joint (DRUJ) top

Before starting the operation the uninjured side should be tested as a reference for the injured side.

After fixation, the distal radioulnar joint should be assessed for forearm rotation, as well as for stability. The forearm should be rotated completely to make certain there is no anatomical block.


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Method 1

The elbow is flexed 90° on the arm table and displacement in dorsal palmar direction is tested in a neutral rotation of the forearm with the wrist in neutral position.

This is repeated with the wrist in radial deviation, which stabilizes the DRUJ, if the ulnar collateral complex (TFCC) is not disrupted.


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This is repeated with the wrist in full supination and full pronation.


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Method 2

In order to test the stability of the distal radioulnar joint, the ulna is compressed against the radius...


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...while the forearm is passively put through full supination...


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...and pronation.

If there is a palpable “clunk”, then instability of the distal radioulnar joint should be considered. This would be an indication for internal fixation of an ulnar styloid fracture at its base. If the fracture is at the tip of the ulnar styloid consider TFCC stabilization.

v2.0 2013-07-09