Nerve transfers to anterior interosseous nerve for restoration of finger flexion in spinal cord and brachial plexus injury: a systematic Review and individual-patient-data meta-analysis

Study Design: Systematic review and meta-analysis. Objectives: Cervical spinal cord injury (SCI) and brachial plexus injury (BPI) can result in hand paralysis. Reconstruction of hand motion is associated with improved functionality and quality of life. We synthesized the outcomes of finger and thumb flexion after various nerve transfers to the anterior interosseous nerve (AIN). Methods: A systematic literature review and meta-analysis was performed according to the PRISMA guidelines. Successful finger and thumb flexion recovery was defined as Medical research council (MRC) grade ≥3. Results: In total, 23 studies with 99 patients and 120 nerve transfers to the AIN were performed. The mean interval from injury to surgery was 12.8 months and mean follow-up duration was 24 months. Overall, 81/120 (67.5%) and 68/102 (66.7%) hands achieved successful finger and thumb flexion recovery, respectively. Individual-patient-data were available for 94 nerve transfers. Type of injury (SCI vs BPI/peripheral) did not affect finger flexion outcomes (OR 1.92, 95%CI 0.74–5.0, p = 0.17). On multivariate analysis adjusted for mechanism of injury, timing of injury to surgery and duration of follow-up, utilization of the brachioradialis (BR) branch (25%, 1/4, OR 0.01, 95%CI 0.0006–0.44, p = 0.01) and brachialis (BA) branch (59%, 30/51, OR 0.06, 95%CI 0.006–0.68, p = 0.02) as donors, were associated with statistically significant lower odds of successful finger flexion recovery compared to extensor carpi radialis brevis (ECRB) use (95%, 19/20). Conclusions: Similar outcomes were observed with SCI and BPI/peripheral type injuries. ECRB utilization as a donor was superior to BA or BR branch in terms of successful finger flexion recovery.