title: Reverse end-to-side nerve transfer: from animal model to clinical use.
abstract: OBJECTIVE
  Functional recovery after peripheral nerve injury is predominantly influenced by time to reinnervation and number of regenerated motor axons. For nerve injuries in which incomplete regeneration is anticipated, a reverse end-to-side (RETS) nerve transfer might be useful to augment the regenerating nerve with additional axons and to more quickly reinnervate target muscle. This study evaluates the ability of peripheral nerve axons to regenerate across an RETS nerve transfer. We present a case report demonstrating its potential clinical applicability.
  
  
  METHODS
  Thirty-six Lewis rats were randomized into 3 groups. In group 1 (negative control), the tibial nerve was transected and prevented from regenerating. In group 2 (positive control), the tibial and peroneal nerves were transected, and an end-to-end (ETE) nerve transfer was performed. In group 3 (experimental model), the tibial nerve and peroneal nerves were transected, and an RETS nerve transfer was performed between the proximal end of the peroneal nerve and the side of the denervated distal tibial stump. Nerve histomorphometry and perfused muscle mass were evaluated. Six Thy1-GFP transgenic Sprague Dawley rats, expressing green fluorescent protein in their neural tissues, also had the RETS procedure for evaluation with confocal microscopy.
  
  
  RESULTS
  Nerve histomorphometry showed little to no regeneration in chronic denervation animals but statistically similar regeneration in ETE and RETS animals at 5 and 10 weeks. Muscle mass preservation was similar between ETE and RETS groups by 10 weeks and significantly better than negative controls at both time points. Nerve regeneration was robust across the RETS coaptation of Thy1-GFP rats by 5 weeks.
  
  
  CONCLUSIONS
  Axonal regeneration occurs across an RETS coaptation. An RETS nerve transfer might augment motor recovery when less-than-optimal recovery is otherwise anticipated.
  
  
  METHODS
  Therapeutic I.
authors.affiliation: Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: Santosh S
authors.initials: SS
authors.lastname: Kale
authors.forename: Simone W
authors.initials: SW
authors.lastname: Glaus
authors.forename: Andrew
authors.initials: A
authors.lastname: Yee
authors.forename: Michael C
authors.initials: MC
authors.lastname: Nicoson
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Hunter
authors.forename: Susan E
authors.initials: SE
authors.lastname: Mackinnon
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Johnson
mesh_terms: D000368:Aged; D000818:Animals; D001369:Axons / Q000502:physiology; D020430:Cubital Tunnel Syndrome / Q000503:physiopathology / Q000601:surgery; D005240:Feasibility Studies; D006801:Humans; D008297:Male; D009416:Nerve Regeneration; D016067:Nerve Transfer / Q000379:methods*; D010525:Peripheral Nerves / Q000601:surgery*; D010543:Peroneal Nerve / Q000502:physiology / Q000601:surgery; D051381:Rats; D011917:Rats, Inbred Lew; D017207:Rats, Sprague-Dawley; D013979:Tibial Nerve / Q000502:physiology / Q000601:surgery; D014459:Ulnar Nerve / Q000503:physiopathology / Q000601:surgery