Secondary Ulnar Nerve Reconstruction of High Ulnar Nerve Injuries: A Comparative Study of Sural Grafting and Anterior Interosseous Nerve Transfer

Objectives: High ulnar nerve injuries often cause severe functional impairment, and the best secondary repair method remains debated. This study compared the effectiveness of sural nerve grafting and anterior interosseous nerve (AIN) transfer following failed primary ulnar nerve repairs. Methods: This retrospective cohort study included 42 patients with isolated high ulnar nerve injuries who required secondary surgical intervention. Patients were allocated to either the sural nerve grafting (n = 23) or AIN transfer (n = 19) group based on predefined clinical criteria. Motor and sensory functions were assessed using the British Medical Research Council (BMRC) grading system and a two-point discrimination (2PD) test. Grip and pinch strength were measured, and functional recovery was evaluated using the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire. Results: The AIN transfer group exhibited significantly superior motor recovery, with 68.5% of patients achieving BMRC grades M4-M5, compared to only 17.4% in the sural grafting group (P = 0.03). Sensory recovery was also markedly better in the AIN group, with a higher proportion of patients reaching BMRC sensory grades S3-S4 (P = 0.04). Additionally, the AIN transfer group demonstrated significantly greater grip strength (30.1 +/- 6.1 kg vs. 24.3 +/- 5.2 kg; P = 0.03) and pinch strength (7.2 +/- 1.5 kg vs. 5.8 +/- 1.3 kg; P = 0.04). Improvement in DASH scores was more substantial in the AIN group (-26.6 +/- 5.7 vs. -14.6 +/- 4.3; P = 0.02), indicating better functional recovery. Although the AIN group showed a trend toward improved 2PD, the difference was not statistically significant (P = 0.18). Conclusion: AIN transfer provides superior outcomes compared to sural nerve grafting for the secondary repair of high ulnar nerve injuries, demonstrating significantly enhanced motor and sensory recovery, grip and pinch strength, and overall functional improvement.