Morphometric study of the posterior interosseous nerve and its application to nerve grafting and orthopedics

Abstract

Introduction: The PIN is an excellent option for autogenous grafts due to the absence of cutaneous branches in its terminal portion, making it ideal for digital nerve grafts. This study aims to perform a morphometric analysis of the PIN in cadavers, with the objective of determining the length of the nerve available for grafting and the proximal extension in relation to Lister's tubercle, contributing to improving surgical approaches. Material and Methods: The present study involved the dissection of 20 limbs (right and left) from male cadavers previously fixed with 10% formalin solution. The radial nerve was identified in the arm between the brachialis and brachioradialis muscles and dissected from proximal to distal. The deep branch of the radial nerve (PIN) was highlighted, so that the posterior compartment of the forearm was dissected. The last muscular branch of the PIN was identified. The beginning of the last muscular branch of the PIN was considered as point “A”. The proximal edge of the pseudoganglion was considered as point B. The tip of Lister's tubercle was considered as point C. These distances were measured with a digital caliper. Differences between sides were compared by the paired Student's t-test A p-value < 0.05 was considered significant for the analyses. Results: In all limbs the posterior interosseous nerve (PIN) was consistently observed. After exiting the lower border of the supinator muscle, the PIN bifurcated into two branches following its supply to the extensor pollicis longus: the medial branch terminated in the extensor indicis, while the lateral branch extended along the interosseous membrane beneath the extensor pollicis longus. Measurements from Point A to Point C showed a mean of 5.87 cm (SD 1.65, range 3.8–7.95 cm), while measurements from Point B to Point C had a mean of 4.18 cm (SD 0.77, range 2.78–5.85 cm). No significant differences were found between sides (p > 0.05). Conclusion: The findings of the present study corroborate well with the existing literature. The posterior interosseus nerve can safely be harvested without significant complications due to its easy location, anatomy and length availability.