Anatomic Landmarks to Identify the Radial Nerve during the Posterior Approach of the Humerus: A Cadaveric Study

Introduction: Identification of the radial nerve and preventing injury to it is crucial, while surgically approaching the humerus from the posterior aspect to treat fractures of the midshaft or the distal third of the bone. Aim: To identify certain anatomic landmarks, using which the radial nerve could be identified during surgical intervention, in order to prevent iatrogenic injury to the nerve. Materials and Methods: Twenty-eight arms belonging to 14 adult cadavers (10 male and 4 female) were used for this study. The distance between the radial nerve on the posterior humerus and the point of confluence of the long and lateral heads of the triceps with the triceps aponeurosis was measured. Statistical analysis using Student's paired t-test was done between the right and left sides. In the distal third of the humerus, the distance of the radial nerve and the lateral border of the triceps aponeurosis at four sites were determined. Results: The mean distance from the point of confluence to the radial nerve along the posterior humerus was 39.7 +/- 11.8 mm. The radial nerve passed adjacent to the lateral border of the triceps aponeurosis at a distance of 12-19.5 (+/- 3.27) mm. It was never found to be closer than 4.6 +/- 2.54 mm to the aponeurosis. Conclusion: The present study is useful for orthopaedicians while undertaking the surgical management of humeral fractures. The point of confluence and the triceps aponeurosis are two anatomic landmarks that can be used to locate the radial nerve.