The purpose of this investigation was to evaluate the ability of a specific growth factor combination, nerve growth factor (NGF) and ciliary neurotrophic factor (CNTF), to enhance peripheral nerve regeneration. Eight groups of eight Sprague-Dawley rats underwent repair of a nerve gap defect: Group A (immediate repair), Group B (intact nerve bridge), Group C (nerve autograft), Group D (gap in situ), Group E (NGF + CNTF), Group F (NGF), Group G (CNTF), and Group H (saline). Twelve weeks after surgery, analysis included the measurement of the isometric force of muscle contraction for the tibialis anterior muscle and tissue harvesting for both quantitative and qualitative analysis. When evaluating muscle contraction force, there was no statistically significant difference among the experimental groups receiving a growth factor injection and the normal saline control group. The hypothesis of this study was that peripheral nerve regeneration could be enhanced by the combination of NGF and CNTF. The evidence does not support this hypothesis.

This study investigated the intact nerve bridge technique for overcoming peripheral nerve gap defects in a rabbit model. To create the intact nerve bridge, a 1-cm segment of the peroneal nerve is resected leaving a gap defect. The proximal and distal peroneal nerve stumps are sutured 1 cm apart, in an end-to-side fashion, to the intact tibial nerve epineurium. Four experimental groups were used (n = 10): primary repair of resected segment; intact nerve bridge; nerve autograft; and gap in situ control. Evaluation after 12 weeks included measurement of isometric muscle contraction force, axonal counting, wet muscle weights, and histologic examination. The results of this study support two main conclusions, in a rabbit model: (a) regenerating axons can use the epineurium of an intact nerve to bridge a gap defect; (b) there is no significant difference in the functional recovery between standard nerve autografts and the intact nerve bridge technique.