Floor plan - 2013 Annual Meeting - American Association for Hand ...

A Study of Modality Specific Nerve Regeneration in the Rat Femoral Nerve
Institution where the work was prepared: Washington University, St. Louis, MO, USA
David H. Kawamura, MD; Gregory H Borschel; Daniel A Hunter; Susan E Mackinnon; Thomas HH Tung; Washington
University in St. Louis
BACKGROUND/HYPOTHESIS:
Today, autologous sensory nerve grafting is the standard of care for the repair of peripheral nerve gaps. Motor nerve defects are frequently
reconstructed with grafts harvested from superficial sensory nerves due to the morbidity associated with motor nerve harvest.
However, some investigators have suggested that modality matching, i.e. repairing motor nerves with motor grafts and sensory nerves
with sensory grafts, may improve nerve regeneration. The aim of this study is to compare nerve regeneration between modality
matched and modality mismatched grafts in a clinically-representative scenario utilizing unifascicular nerve grafts in a rodent model.
MATERIALS AND METHODS:
Isogeneic nerve grafts were harvested from the quadriceps branch of the femoral nerve (motor), femoral cutaneous branch (sensory),
and peroneal nerve (mixed). Grafts were 10mm in length and were used to reconstruct a 5mm defect in the quadriceps branch or cutaneous
branch of a recipient rat. A total of 48 Sprague-Dawley rats were randomized to six groups of eight animals each. The groups
represented six different combinations of donor and recipient nerves, as follows: 1) motor/motor, 2) sensory/motor, 3) mixed/motor, 4)
sensory/sensory, 5) motor/sensory, 6) mixed/sensory. Animals were sacrificed after 7 weeks and nerves were harvested for analysis. The
recipient nerve distal to the graft was fixed, stained, and sectioned for histomorphometry.
RESULTS:
Histologic sections revealed robust regeneration through the graft and into the distal nerve in all groups. Histomorphometric analysis
of nerve sections distal to the graft revealed no significant difference between any of the six experimental groups with regard to nerve
fiber count, fiber density, fiber width, nerve area, or percent nerve. Assessment of fiber size revealed that sensory and motor grafts supported
regeneration of a similar number of large-diameter axons when grafted into motor nerve.
CONCLUSION:
Our data demonstrate that injured peripheral axons do not regenerate in a manner specific to motor or sensory modality. On the contrary,
motor and sensory nerve regeneration occurs to an equal degree in motor, sensory, and mixed nerve grafts. In addition, equal
numbers of large-diameter fibers regenerated through sensory and motor grafts in the quadriceps branch. This indicates that sensory
grafts are equal to motor in their ability to support regenerating motor axons. Our findings support the continued use of nerve grafts
derived from sensory nerves when reconstructing motor nerve defects in human patients. Further studies will be undertaken to compare
end organ reinnervation and functional recovery between modality matched and mismatched grafts.
Limb Length Discrepancy in Obstetrical Brachial Plexus Injury
Institution where the work was prepared: McMaster Children's Hospital, Hamilton, ON, Canada
James Bain, MD, MSc; Carol DeMatteo; Deborah Agro; Hamilton Health Sciences and McMaster University
Obstetrical brachial plexus injury (OBPI) has a variable natural history depending upon severity of nerve trauma. Approximately 50 % of
children will completely recover, many will be left with a functional but short, impaired arm.
PURPOSE:
To determine if OBPI results in differences in limb length comparing the affected to unaffected limbs.
METHODS:
A prospective database of OBPI patients from 1998-2007 has been reviewed. Limb lengths were manually measured by the same investigator
at standard times in new patients and at 3 and 12 month follow-up. Arm length was measured from the acromion to the olecranon
and forearm length from the olecranon to the ulnar styloid. Inclusion criteria included those with full records and early presentation
to our clinic. Comparisons were made between affected and unaffected limbs, and results correlated with total active motion scale
scores (AMS) using SAS statistical software.
RESULTS:
Twenty-four children had complete scores at 3 months and there was a significant reduction in the limb length of the affected side
(p