Intraoperative identification of the radial nerve in posterior plate fixation for humeral shaft fractures using the olecranon as a landmark: a retrospective case series

Purpose: The radial nerve is vulnerable to iatrogenic injury during posterior plate fixation of humeral shaft fractures because of its close relationship to the posterior humerus. This study evaluated the distance from the olecranon tip to the radial nerve as a simple intraoperative landmark.Methods: Eleven adult patients who underwent posterior plate fixation for humeral shaft fractures between 2011 and 2016 were retrospectively reviewed. Using a posterior paratricipital approach, the radial nerve was identified along the spiral groove. With the elbow flexed at 90°, the distance from the olecranon tip to the point where the radial nerve crossed the posterior humerus was measured intraoperatively using a sterile ruler. Patient demographic and clinical data were reviewed, and the relationship between patient height and nerve distance was analyzed using Pearson correlation analysis.Results: Eleven patients (eight males and three females) were analyzed. The median age was 34 years (IQR, 27–39 years; range, 20–46 years). The intraoperative distance from the olecranon tip to the radial nerve had a median of 13.2 cm (IQR, 13.0–13.4 cm; range, 12.9–13.8 cm). No significant association was found between patient height and nerve distance (r=0.13, p=0.66). All fractures achieved bone union, and no postoperative radial nerve palsy occurred.Conclusion: In this series, the radial nerve consistently crossed the posterior humerus approximately 13 cm proximal to the olecranon tip. The olecranon may serve as a simple intraoperative landmark to help anticipate the radial nerve location during posterior humeral fixation.