[Neurotization of the deep branch of ulnar nerve and the thenar branch of median nerve with the pronator quadratus branch of anterior interosseous nerve by end-to-side transfer. An anatomic study].

Proximal or middle lesions of median or ulnar nerves are responsible for a great loss of hand motor function. Neurotization of either deep ulnar branch of ulnar nerve (DBUN) or recurrent (thenar) branch of median nerve (RBMN) with the nerve to quadratus pronator (NPQ) from the anterior interosseous nerve (AION) could reduce length of axonal growth and therefore the reinnervation lead-time of hand intrinsic muscles. We studied the anatomy of these three nerves, to help surgeon choosing his (her) technique and approach. Twenty-three cadaver forearms were dissected. End-to-side sutures were performed to mimic these neurotizations. Distances between nerve sutures and ulnar styloid process (USP) or trapeziometacarpal joint (TM) were measured. All the sutures but one RBMN could be done. On average sutures were distant from USP by 44±17mm (neurotization of DBUN), from TM by 62±15mm (neurotization of RBMN). Knowledge of average distance to perform these neurotizations should allow choosing the best reduced approach of RBMN and DBUN. Neurotizations of DBNU and RBMN with NPQ were feasible for lesions located at 6.1cm upstream USP and 7.7cm upstream TM, respectively. End-to-side sutures remain to be clinically evaluated.