No neurovascular damage after creation of an accessory anteromedial portal for arthroscopic reduction and fixation of coronoid fractures

Purpose: Arthroscopic reduction and internal fixation for coronoid process fractures has been proposed to overcome limitations of open approaches. Currently, arthroscopy is most frequently used to assist insertion of a retrograde guide wire for a retrograde cannulated screw. The present anatomical study presents an innovative arthroscopic technique to introduce an antegrade guide wire from an accessory anteromedial portal and evaluates its safety and reproducibility. Methods: Six fresh-frozen cadaver specimens were obtained and prepared to mimic an arthroscopic setting. The coronoid process was localized and a 0.9 mm Kirschner wire was introduced from an accessory anteromedial portal, located 2 cm proximal to the standard anteromedial portal. At the end of the procedure, a lateral radiograph was taken to verify the Kirschner wire position and open dissection was conducted to evaluate possible damage to neurovascular structures. Results: The Kirschner wire was drilled without complications in the coronoid process of all six specimens. Damage of the brachial artery, the median nerve, and the ulnar nerve did not occur in any specimen. A corridor between the brachialis muscle, the median intermuscular septum, and the pronator teres could be identified as suitable for the wire passage. Conclusion: This study presents a safe and reproducible technique combining the possibility to introduce a guide wire from the anteromedial part of the coronoid, under direct visual control, with a completely arthroscopic approach. This wire can guide the introduction of a retrograde cannulated screw from the dorsolateral ulna to the tip of the coronoid. This new arthroscopic approach permits to obtain improved visual control over coronoid process fixation, without endangering neurovascular structures.