Course of the Radial Nerve in Relation to the Center of Rotation of the Elbow—The Need for a Rational Safe Zone for Lateral Pin Placement

Purpose To investigate the course and variability of the radial nerve along the lateral humerus in relation to the center of rotation of the elbow joint in the context of lateral pin placement for hinged external fixation. Methods A total of 95 formalin-fixed upper extremities were dissected. The course of the radial nerve along the lateral aspect of the humerus was measured at 3 landmarks with respect to the center of rotation of the elbow. We analyzed the data and the landmark positions correlated with the length of the humerus. Results The measured positions of 3 landmarks of the radial nerve in the lateral aspect of the humerus ranged from 19% to 43% of the length of the humerus and were located, on average, 6.0, 9.7, and 13.5 cm from the lateral center of rotation. Conclusions These data help predict the humeral course of the radial nerve and define a safe zone for pin implantation. However, because of variability in the course of the radial nerve, a safe zone cannot fully ensure prevention of iatrogenic injury to the nerve. The safest method of pin application remains mini-open dissection and visual implantation. Clinical relevance Based on this cadaveric study, it is not possible to define a rational safe zone. The safest method of pin application for dynamic external fixation of the elbow is to perform a mini-open dissection with direct visualization.