Inserting percutaneous instrumentation through safe zones reduces the risk of damage to neurovascular structures.
2. Proximal third of the humerus
Pins or screws are inserted from a lateral (alternatively from an anterolateral or a posterolateral) direction through the deltoid muscle.
Avoid damage to the long head of biceps tendon.
The tips of the pins should just perforate the far cortex. If inserted too deeply, 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.
3. No safe zone in the middle third of the humerus
Avoid pin placement in the middle third as the radial nerve, which is in close relationship with the dorsal diaphyseal cortex, can be damaged.
If it is felt to be essential to place a pin in the middle third the radial nerve needs to be identified and protected.
4. Distal third of the humerus
Pins are inserted from a posterior (alternatively from a posterolateral or a 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. Insertion too deeply can damage the median nerve and/or the brachial artery.
5. Proximal forearm
Pins are inserted from a posterior aspect directly into the proximal third of the ulnardiaphysis. It is an easily recognizable and palpable bone. Avoid insertion into the radius, in order not to impair rotational motion of the forearm.
The tips of the pins or screws should just perforate the far cortex. Insertion too deep can damage the median nerve and/or ulnar artery.