Anterior Interosseous Nerve to Pronator Quadratus Transfer to Restore Intrinsic Function: An Adjunct to Cubital Tunnel Decompression

Abstract

Background Injury or compression of the ulnar nerve impairs fine motor control, intrinsic hand function, and sensation in the small and ulnar side of the ring finger. Anterior interosseous nerve to pronator quadratus (AINPQ) transfer offers a potential solution, leveraging this expendable nerve to enhance the recovery of the ulnar nerve's motor function. Method This single-unit retrospective case series evaluates seven patients undergoing combined cubital tunnel decompression and AINPQ transfer for severe ulnar neuropathy. Data were collected from December 2020 to January 2023, including age, hand dominance, affected limb, and symptom duration (pain, sensory changes, motor weakness). The cohort comprised cases of both compressive and traumatic ulnar nerve injuries. Electrophysiological findings, intraoperative observations, postoperative assessments, and complications were recorded. Outcomes were measured using the Disabilities of the Arm, Shoulder, and Hand questionnaire at least six months postoperatively, with success defined as a =1 Medical Research Council (MRC) grade improvement or a score of >3 in thumb adduction, intrinsic function, or grip strength. Results All patients demonstrated a motor function improvement of =1 MRC grade following AINPQ transfer. The complication rate was low, with no reported cases of functional deterioration or infection, consistent with existing literature. One patient reported a painful scar, attributed to the cubital tunnel decompression procedure. Conclusion This study supports the adjunctive use of AINPQ with cubital tunnel decompression in severe ulnar nerve compression or injury cases. AINPQ shows potential in accelerating reinnervation and improving hand function within 12-14 months of symptom onset, though larger prospective studies are necessary for validating and refining patient selection criteria.