Distal nerve transfers for ulnar nerve reinnervation and hand function restoration

Ulnar nerve injuries lead to severe intrinsic hand muscle dysfunction and major impairment of grip, pinch, and quality of life. Distal nerve transfers have been introduced to overcome the limitations of conventional repair and grafting by shortening the regeneration distance and improving reinnervation of intrinsic muscles.

Can distal anterior interosseous nerve to deep motor branch of the ulnar nerve (AIN-to-UN-DMB) transfer restore intrinsic hand function and improve patient-reported quality of life in proximal ulnar nerve injuries?

Twelve patients with proximal ulnar nerve injuries underwent distal AIN-to-UN-DMB transfer and were prospectively evaluated at 24 months postoperatively. Outcomes included intrinsic muscle strength graded by the BMRC scale, Egawa's sign, dynamometric assessment of grasp and pinch strength, and quality of life measured using the PNSQoL questionnaire.

At final follow-up, intrinsic muscle strength improved markedly: 27 muscles achieved M4 and 14 achieved M3 strength, compared with universal M0 preoperatively. Grasp strength increased from a mean of 42.3% to 82.5%, and pinch strength from 37.4% to 80.5% of the contralateral hand. Overall satisfactory functional recovery was achieved in 87.5% of patients. Mean PNSQoL score improved significantly from 47.7 preoperatively to 74.4 postoperatively (p < 0.001), with all patients reaching very good or excellent quality-of-life categories.

Distal AIN-to-UN-DMB transfer enables meaningful restoration of intrinsic hand function, substantial gains in grasp and pinch strength, and significant improvement in quality of life, representing an effective reconstructive option for proximal ulnar nerve injuries.