Ulnar Nerve Injuries (Sunderland Grade V): A Simplified Classification System and Treatment Algorithm

Background: This study introduced a novel technical approach to the ulnar nerve injuries. The ulnar nerve was divided into 4 distinct surgical zones, each mandating a unique management strategy. Methods: A prospective observational study was conducted to verify the hypothesized algorithm. The study included 110 patients diagnosed with ulnar nerve injury (Sunderland grade 5). We divided the patients into 4 groups depending on the site of injury. Each group of patients was managed in accordance with a particular strategy, exploiting nerve transfer techniques along with the updated knowledge of the internal topography of the ulnar nerve. The motor recovery of the small muscles of the hand was assessed after 2 years of follow-up, using the disabilities of the arm, shoulder, and hand score, and other parameters including key pinch strength, hand grip strength, and the motor power of the first dorsal interosseous muscle on the Medical Research Council scale. Results: The mean values of the disabilities of the arm, shoulder, and hand score, key pinch strength, and hand grip strength showed a statistically significant improvement across all patient groups (P < 0.05). Of those with zone (I) injury, postoperatively, 79.9% patients attained a first dorsal interosseous muscle power grade >3 on the Medical Research Council scale, while 93.9% of patients with zone (II) damage achieved the same result. Surprisingly, 84% of patients included in both zones (III) and (IV) also recovered to the same extent. Conclusions: This prospective observational study examined and successfully confirmed the validity of our proposed novel algorithm for the management of ulnar nerve injuries (Sunderland grade 5).