Effect of end-to-side anterior interosseous nerve transfer in proximal ulnar nerve injuries: A comparative study.

Background: Few studies have described the efficacy of end-to-side (ETS) nerve transfer for high ulnar nerve injuries. This study aimed to compare the intrinsic functional outcomes of patients who underwent ETS nerve transfer for proximal ulnar nerve transection injuries and those of patients who did not. Materials and methods: We retrospectively evaluated 15 patients who underwent primary repair of proximal ulnar nerve injuries. Patients were divided into groups based on whether ETS nerve transfer was performed. Postoperative intrinsic atrophy, clawing, ability cross finger Froment sign, Wartenberg sign, and Disabilities of Arm, Shoulder, and Hand (DASH) scores were evaluated and compared between groups. Additionally, two-point discrimination, grip strength, pinch strength, and intrinsic muscle strength of the hand were evaluated and compared between groups. Results: Nine patients comprised the ulnar nerve repair (UNR) group and six patients comprised the UNR with SETS (UNR + ETS) group. No significant differences in intrinsic atrophy, clawing, ability to cross finger, Froment sign, Wartenberg sign, and DASH scores were observed between groups. No significant differences in the strength of the abductor digiti minimi, grip strength, pinch strength, and two-point discrimination were observed between groups. A statistically significant difference only in the strength of the first dorsal interosseous muscle was observed between groups. Conclusion: Our comparative study showed little or no benefit of ETS-AIN transfer for high ulnar nerve injuries.