Ulnar nerve monitoring during percutaneous pinning of supracondylar fractures in children

Background: Supracondylar fractures of the humerus in children are frequently managed by closed reduction and percutaneous pinning. Insertion of medial and lateral pins is more stable than lateral pinning alone, but carries an increased risk for ulnar nerve damage. This study describes the use of electrical stimulation concurrent with medial pin insertion as a monitoring technique for avoiding iatrogenic ulnar nerve injury. Methods: A retrospective review was conducted on 138 children, mean age 5.6 years (SD±2.5), who were admitted to the hospital between 2007 and 2010 with uncomplicated supracondylar fractures, Gartland type II and above, and intact neurovascular presentation. The location of the ulnar nerve was identified and marked preoperatively by observing twitch contractions in response to electrical stimulation. The medial pin served as an active electrode during pin insertion, and repeated stimulation throughout the insertion process ensured no contact with the response of the ulnar nerve. After pin insertion, ulnar nerve stimulation was used again to ensure nerve continuity viability. Results: All fractures were stabilized with 2 to 4 cross K-wires (size 1.6 mm), with number depending on stability of the fracture. The children were discharged home 2 days after fracture fixation, with no iatrogenic ulnar nerve injury observed in any of the children. The only postoperative complication involved 2 cases of anterior interosseus nerve neuropraxia, which resolved spontaneously after 4 to 6 months. Primary fracture healing was achieved without nonunions or delayed unions in all cases. Conclusions: Ulnar nerve stimulation before and during the percutaneous pinning of supracondylar fractures in children is a simple, economical, and easy-to-implement technique that can prevent iatrogenic ulnar nerve injury. Level of Evidence: Level IV.