Surgical importance of using musculo-aponeurotic landmarks as a guide to identify the radial nerve in posterior approach for humeral fractures a cadaveric study in a south indian population

Background & Aims: Long course of the radial nerve and its proximity to the humerus makes Radial Nerve (RN) prone to injury in
diaphyseal fractures. In an effort to maintain its integrity, soft tissue landmarks can be readily made use of to provide facile nerve
identification, as osseous landmarks might get altered in fractures. The aim of this study was to provide an idea of safe zone for securing
radial nerve in relation to soft tissue structures and thereby, preventing the concomitant iatrogenic injury.
Materials & Methods: 40 Upper limb specimens from 20 cadavers were dissected. The radial nerve was identified proximal to the
apex of Tricipital aponeurosis (TA) in posterior arm, at the level of entry into the lateral inter muscular septum and along the lateral
border of TA. The mean distance between the radial nerve and aponeurosis was measured at all the three sites to find the safe zone for
securing the radial nerve during surgeries.
Results: The radial nerve was found proximally from the medial apex of tricipital aponeurosis at a distance of 43.49 ± 6.67 mm (range
30.34-55.72 mm) within the muscle belly of triceps. The minimal permissible distance for the triceps split was 3.03 cm from the medial
apex for both right and left arms. The distance of above 15 mm (range from 15.56 to 47.47mm) from the lateral border of tricipital
aponeurosis was considered as a safe zone and no branches of the radial nerve were found in this zone. Radial nerve was identified
along its course in the range of 15.56 to 47.47 mm from the lateral border of TA and this should be taken into consideration by the
operating surgeon.
Conclusion: The Tricipital aponeurosis is a useful soft tissue landmark to secure the radial nerve safely throughout its course in the
arm. Knowledge of safe and dangerous zones of the radial nerve would help the orthopedic surgeons to avoid the risk of iatrogenic
nerve injury, which is not an uncommon phenomenon.