- Safe zones
Safe zone in the proximal third
Pins or screws are inserted from a lateral (alternatively from an anterolateral or posterolateral) direction through the deltoid muscle.
Avoid damage to the long biceps tendon.
The tips of the pins should just perforate the far cortex. If too deep, the tips can injure the medial neurovascular bundle.
Damage to the axillary nerve must be avoided. This nerve runs dorsolaterally around the humeral metaphysis, about 5 cm below the greater tuberosity.
(See also pin placement technique in external fixation procedure)
No safe zone in the middle third
Avoid pin placement in the middle third as the radial nerve, which is in close relationship with the dorsal diaphyseal cortex, can be damaged.
Safe zone in the distal third
Pins are inserted from a posterior (alternatively from a posterolateral or posteromedial) direction through the triceps muscle.
Avoid penetration of the olecranon fossa.
The tips of the pins or screws should just perforate the far cortex. Placement too deep can damage the median nerve and/or brachial artery.