- Safe zones for pin insertion
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 from a posterolateral aspect directly to the proximal third of the ulna.
It is an easily recognizable and palpable bone. Avoid insertion into the radius to preserve rotational motion of the forearm.
The tips of the Schanz screws or screws should just perforate the far cortex. If placed too deep, the median nerve and/or ulnar artery are at risk.
Additional ulnar fixation
For adequate support of the elbow region, distal fixation will need to extend additionally into the middle or distal ulna.
Pin placement along the whole shaft is easy between the extensor carpi ulnaris and the flexor carpi ulnaris. Remember the dorsal sensory branch of the ulnar nerve crossing the ulna just proximal to the wrist.