Comparison of the Effects of Two-Staged Nerve Graft Application and One-Stage Nerve Graft Application on Axonal Regeneration in Long Nerve Defect Reconstruction

Introduction: Nerve grafts may be necessary to reconstruct long nerve defects.

However using a long nerve graft to reconstruct a large defect, is far from stimulating the axonal regeneration, due to the degeneration and endoneural collagenization at the distal part of the graft.

In this study, to abstain from collagenization at the distal segment of a long nerve graft, two nerve grafts were applied in two-stages to repair a long nerve defect.

Methodology and Material: Two cm long nerve defect was created on the right peroneal nerves of rats (n = 18). In one-stage repair (control) group (n = 9), the excised 2cm long nerve segment was transposed and sutured back to the defect. In two-stage repair (experiment) group (n = 9), the nerve defect was reconstructed in two different time periods with three weeks interval by two nerve grafts. Six weeks after creating nerve defects in both groups, electrophysiological (EMG) evaluation was performed and biopsies were taken from nerve grafts for axon count. Results were statistically analyzed.

Results: There was a significant decrease in the axon counts of the distal 1cm nerve graft segments of both groups when compared with the proximal segments. The axon count at the distal nerve segment of the two-staged repair group was determined to be statistically higher than distal segment of one-stage repair group. Comparison of electrophysiological assessment results revealed that the latency values were significantly shorter and amplitude values were significantly higher for the experiment group than control group.

Conclusions: Process of collagenization at the distal part of a long, single segment nerve graft prevents the progression of the in-growing axons and nerve regeneration.

In staged nerve graft application, the axons in-growing toward the distal segment encounter with a disadvantage of passing over three suture lines.

But staged nerve grafting has a greater advantage of stimulating axonal regeneration, and preventing collagenization taking place at the distal half of a long nerve graft, by using a fresh shorter nerve grafts in each stage.

According to axon count and EMG results of this study, using fresh nerve graft segments in two-stages to repair a long nerve defect has a statistically significant benefit on nerve regeneration.