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Authors

Harry Hoyen, Simon Lambert, Joideep Phadnis

Executive Editor

Simon Lambert

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Safe zones for percutaneous pins or screws

1. Introduction

In the humerus, there is a high risk of nerve injury by percutaneous pin placement. A mini-open technique for pin placement is recommended, particularly around the elbow.

2. Pin placement in the middle third of the humerus

It is not safe to place the pins percutaneously in the humerus.

If pin placement is necessary, the radial nerve must be identified and protected before drilling and pin insertion.

The humeral pins may be inserted in the region of the deltoid insertion zone to avoid the radial nerve.

If a pin needs to be placed more distally, it should be inserted from the posterolateral aspect of the humeral shaft.

Pearl: Make a bigger incision to allow insertion of two pins and retraction of the radial nerve (see also neurological protection and handling).
Neurovascular anatomy in the middle third of the humerus

This case shows a patient with a radial nerve injury caused by fixator pins.

Case with radial nerve injury caused by fixator pins

This intraoperative photo shows the radial nerve in continuity but tethered in scar close to where the pins had been placed. Two of the holes can be seen beneath the radial nerve.

Intraoperative photo showing the radial nerve in continuity but tethered in scar close to where the pins had been placed

3. Safe zone in the proximal forearm

In the forearm, the pins are placed into the ulna.

Pitfall: Do not place pins in the radius.

Insert pins into the lateral or posterolateral part of the proximal or middle third of the ulna.

It is a subcutaneous bone and therefore easily palpable. Check pronation and supination after insertion to make sure the Schanz screw does not impinge the radius.

Safe zone for pin placement in the proximal forearm
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