- Safe zones
Inserting percutaneous instrumentation through safe zones reduces the risk of damage to neurovascular structures.
Safe zone in the humerus distal third
Schanz screws are inserted from an anterolateral or posterolateral direction through the triceps muscle.
Avoid penetration of the olecranon fossa. Due to the risk of nerve or vascular injury, the tips of the Schanz screws should just perforate the far cortex.
Safe zone in the humerus middle third
In the proximal third of the middle shaft, Schanz screws can be inserted anterolaterally.
Avoid Schanz screw placement distal to this point as the radial nerve is at risk.
Safe zone in the proximal forearm
With the forearm in neutral position, Schanz screws are inserted into the lateral or posterolateral part of the proximal or middle third of the ulna.
It is an easily recognizable and palpable bone. Carefully check pronation and supination after insertion to make sure the Schanz screw does not affect the radius.