Variation in the Branching Pattern of the Radial Nerve Observed during Fixation of the Humerus Shaft: A Case Report

The posterior cord of the brachial plexus typically maintains a consistent branching pattern, and deviations from this norm are exceedingly rare. Even more infrequently encountered are variations in the branching pattern of the radial nerve. The current case report of a 45-year-old male patient presents a unique clinical scenario involving a middle third and distal third humerus shaft fracture, manifesting as the chief complaint of pain during movement, coupled with localised swelling. A posterior approach was employed for surgical intervention due to the expansile nature of the fracture within the middle and distal thirds. During the surgical exploration, an anomalous branching pattern of the radial nerve was observed when transitioning from the posterior to the anterior compartment. This atypical radial nerve branching consisted of a branch extending into the anterior compartment and an accompanying posteroinferior branch, which notably supplied the medial and long heads of the triceps muscle. The present case underscores the imperative role of the orthopaedic surgeon in considering the radial nerve's intricate anatomy while exposing and stabilising segmental humerus fractures. It is of paramount importance to exercise vigilance, as the conventional practice of splitting the triceps muscle should be abstained from until an unusual branching or splitting of the radial nerve is definitively ruled out. The present case report elucidates the significance of meticulous anatomical awareness and surgical technique when addressing such complex humeral fractures, offering insights into the management of these uncommon clinical presentations.