title: Effect of Axonal Trauma on Nerve Regeneration in Side-to-side Neurorrhaphy: An Experimental Study.
abstract: BACKGROUND
  Side-to-side (STS) neurorrhaphy can be performed distally to ensure timely end-organ innervation. It leaves the distal end of the injured nerve intact for further reconstruction. Despite encouraging clinical results, only few experimental studies have been published to enhance the regeneration results of the procedure. We examined the influence of different size epineural windows and degree of axonal injury of STS repair on nerve regeneration and donor nerve morbidity.
  
  
  METHODS
  Three clinically relevant repair techniques of the transected common peroneal nerve (CPN) were compared. Group A: 10-mm long epineural STS windows; group B: 2-mm long windows and partial axotomy to the donor tibial nerve; and group C: 2-mm long windows with axotomies to both nerves. Regeneration was followed by the walk track analysis, nerve morphometry, histology, and wet muscle mass calculations.
  
  
  RESULTS
  The results of the walk track analysis were significantly better in groups B and C compared with group A. The nerve fiber count, total fiber area, fiber density, and percentage of the fiber area values of CPN of the group C were significantly higher when compared with group A. The wet mass ratio of the CPN-innervated anterior tibial muscle was significantly higher in group C compared with group A. The wet mass ratio of the tibial nerve-innervated gastrocnemial muscle was higher in group A compared with the other groups.
  
  
  CONCLUSIONS
  All three variations of the STS repair technique showed nerve regeneration. Deliberate donor nerve axotomy enhanced nerve regeneration. A larger epineural window did not compensate the effect of axonal trauma on nerve regeneration.
authors.affiliation: Department of Orthopaedics, Hatanpää City Hospital, Tampere, Finland; Department of Hand and Microsurgery, Tampere University Hospital, Tampere, Finland; Department of Hand Surgery, Turku University Hospital, Turku, Finland; and §Institute of Clinical Medicine, Department of Biostatistics, and Department of Pathology/Neuropathology, Turku University Hospital, University of Turku, Turku, Finland.
authors.forename: Henrikki
authors.initials: H
authors.lastname: Rönkkö
authors.affiliation: Department of Orthopaedics, Hatanpää City Hospital, Tampere, Finland; Department of Hand and Microsurgery, Tampere University Hospital, Tampere, Finland; Department of Hand Surgery, Turku University Hospital, Turku, Finland; and §Institute of Clinical Medicine, Department of Biostatistics, and Department of Pathology/Neuropathology, Turku University Hospital, University of Turku, Turku, Finland.
authors.forename: Harry
authors.initials: H
authors.lastname: Göransson
authors.affiliation: Department of Orthopaedics, Hatanpää City Hospital, Tampere, Finland; Department of Hand and Microsurgery, Tampere University Hospital, Tampere, Finland; Department of Hand Surgery, Turku University Hospital, Turku, Finland; and §Institute of Clinical Medicine, Department of Biostatistics, and Department of Pathology/Neuropathology, Turku University Hospital, University of Turku, Turku, Finland.
authors.forename: Hanna-Stiina
authors.initials: HS
authors.lastname: Taskinen
authors.affiliation: Department of Orthopaedics, Hatanpää City Hospital, Tampere, Finland; Department of Hand and Microsurgery, Tampere University Hospital, Tampere, Finland; Department of Hand Surgery, Turku University Hospital, Turku, Finland; and §Institute of Clinical Medicine, Department of Biostatistics, and Department of Pathology/Neuropathology, Turku University Hospital, University of Turku, Turku, Finland.
authors.forename: Pasi
authors.initials: P
authors.lastname: Paavilainen
authors.affiliation: Department of Orthopaedics, Hatanpää City Hospital, Tampere, Finland; Department of Hand and Microsurgery, Tampere University Hospital, Tampere, Finland; Department of Hand Surgery, Turku University Hospital, Turku, Finland; and §Institute of Clinical Medicine, Department of Biostatistics, and Department of Pathology/Neuropathology, Turku University Hospital, University of Turku, Turku, Finland.
authors.forename: Tero
authors.initials: T
authors.lastname: Vahlberg
authors.affiliation: Department of Orthopaedics, Hatanpää City Hospital, Tampere, Finland; Department of Hand and Microsurgery, Tampere University Hospital, Tampere, Finland; Department of Hand Surgery, Turku University Hospital, Turku, Finland; and §Institute of Clinical Medicine, Department of Biostatistics, and Department of Pathology/Neuropathology, Turku University Hospital, University of Turku, Turku, Finland.
authors.forename: Matias
authors.initials: M
authors.lastname: Röyttä