Modified Partial Radial to Axillary Nerve Transfer as the Index Procedure for Isolated Axillary Nerve Injury

Axillary nerve injuries often produce profound functional deficits. Beyond expectant management or microsurgical repair, treatment is generally limited to salvage procedures. We present the results of partial radial-to-axillary nerve transfer as the index procedure for treatment of axillary nerve injury after failure of initial conservative management. Minimum 2-year follow-up data was collected and retrospectively analyzed for this single-surgeon cohort of patients with isolated axillary nerve injury. The injury was confirmed with electromyography (EMG), and all patients underwent a nerve transfer as the index intervention. All patients were evaluated for donor-site neuromuscular morbidity, and deltoid muscle biopsies were obtained intra-operatively from 8 patients for motor endplate (MEP) morphometric analysis. Age at time of surgery ranged from 22-68 years, and time from injury to surgery ranged from 2-120 months. Shoulder range of motion (ROM) and Medical Research Council (MRC) muscle strength scores were recorded pre-op and post-op. There were 16 patients in the final sample (median age 56, 15 males, 1 female, 93.75% White, 6.25% Black). Significant improvements in pre-op versus final post-op function were observed: average MRC score improved by 2.82&#xb1; 1.33 (p<0.01), while average active forward- flexion improved by 108.18 &#xb1; 44.17&#xb0; (p < 0.01), abduction by 94.91 &#xb1; 41.58&#xb0; (p < 0.01), and external rotation by 36.67 &#xb1; 27.04&#xb0; (p < 0.01). Surviving MEPs were observed in biopsies of denervated muscles from all patients, even those greater than 6 months from injury. In patients with an isolated axillary nerve injury, when an appropriate donor radial nerve branch can be identified, partial radial-to-axillary nerve transfer as the index treatment procedure offers the possibility of significantly improving shoulder motion and functional strength, without detectable donor-site morbidity. Furthermore, the opportunity for meaningful functional improvement was observed even in patients treated with surgery beyond 6 months from the time of nerve injury and correlated with the observed persistence of deltoid MEPs at later time points. Level IV, Case Series, Treatment Study.