RESUMO
The purpose of this study was to investigate the feasibility of rapid intraoperative elongation of the rat sciatic nerve with the use of tissue expander and to assess its functional recovery. Out of 51 rats 43 had their right sciatic nerve expanded with a 5-ml intraoperative expander over 1 hr and 8 were sham-operated controls. The functional recovery of the nerve was assessed at intervals up to 4 months using the Sciatic Functional index (SFI), neurophysiological indices, and histology. Intraoperative expansion elongated the rat sciatic nerve by about 13%. SFI decreased on the first postoperative day and started to recover by Day 7, reaching almost preoperative values by Days 14 and 30 according to De Medinaceli and Bain-Mackinnon-Hunter formulas, respectively. Latency and motor conduction velocity demonstrated a deterioration after expansion which peaked on Day 1. Recovery started by Day 7 and reached preoperative levels by 60 days. The histological findings indicated minor aberrations immediately after expansion and maximal demyelination with minimal axonal disruption on Day 1. The reparative process started by Day 7 and continued till Day 120 when almost no histological changes were observed. In conclusion, intraoperative nerve expansion successfully elongates the rat sciatic nerve. It also causes functional and morphological abnormalities which are of low to moderate degree, have a short duration, and are reversible. Intraoperative nerve expansion might be a valuable solution in the treatment of short nerve gaps, but its clinical application still needs to be evaluated.