To graft or not to graft? Median to radial nerve transfer in the forearm: an alternative approach to treat proximal radial nerve injuries

Abstract

Background. Reconstruction of proximal radial nerve (RN) injuries via grafting technique brings good recovery of wrist extensors, wherein finger and thumb extensors recover to a lesser degree. The outcomes are strongly dependent on a gap length, timing of procedure, etc. An alternative approach — median (MN) to RN transfer — brings regenerating axons much closer to target muscles.Objective. To compare the recovery of wrist and finger extensors provided by grafting versus distal neurotization technique at proximal RN injury.Methods. Twenty-eight patients with proximal RN injuries underwent 21 reconstruction of RN continuity via grafting technique. Seven patients underwent transfer of MN branches of m. flexor carpi radialis (FCR) and m. palmaris longus (PL) to n. posterior interosseus (PIN) with simultaneous transfer of m. pronator teres (PT) to m. extensor carpi radialis brevis (ECRB).Results. RN grafting brought recovery of the entire complex of thumb, fingers and wrist extensors only in 10 out of 21 cases (47.6 %). Radial wrist extensor(s) recovered in 100 % of cases, thumb extensors — in 85.7 %, finger extensors recovered in 61.9 % patients, with only 47.6 % showed recovery of thumb abductors. Eight patients required additional tendon transfers to restore fingers extension, 3 persons required thumb extension, 11 patients required thumb abduction. All 7 patients (100 %) after MN to PIN transfer received powerful and independent finger and thumb extension, as well as thumb abduction in much earlier terms. PT to ECRB transfer provided powerful and early wrist extension.Conclusions. The outcomes of MN to RN transfer at proximal RN injuries are more predictable, cogent and time-saving compared to the outcomes received with grafting in terms of recovery of full-fledged function of fingers extensors and thumb abductors.