Better nerve regeneration with distally based fascicular turnover flap than with conventional autologous nerve graft in a rat sciatic nerve defect model

Abstract

The authors hypothesize that a fascicular turnover flap will achieve better nerve regeneration in nerve gap repair than a conventional nerve graft in a rat sciatic nerve defect model. Seven-millimeter-long sciatic nerve defects were repaired with an autologous nerve graft, a proximal fascicular turnover flap, or a distal fascicular turnover flap. Following walking footprint analysis 8 weeks after the surgery, the gastrocnemius-soleus muscles of the hind limbs, nerve graft, and flaps were harvested for wet muscle weight assessment, immunohistochemistry, and transmission electron microscopy. The distal fascicular turnover flap exhibited improvement in the sciatic function index similar as that observed for the autologous nerve graft. Histologically, cross sections showed a higher staining intensity for S-100 in the distal fascicular turnover flap group than for S-100 in the nerve graft group (p = 0.01). In the longitudinal sections, the staining intensity for NF-200 was higher in the distal fascicular turnover flap group than in the nerve graft (p = 0.009) and proximal fascicular turnover flap (p = 0.004) groups. More mature capillaries were observed in the proximal (p<0.001) and distal (p = 0.029) fascicular turnover flap groups than in the nerve graft group. Transmission electron microscopy results showed a compact, regular myelin sheath around the myelinated nerve fibers in the distal fascicular turnover flap group, unlike observations in the nerve graft and proximal fascicular turnover flap groups. This study demonstrates better nerve regeneration in nerve gap repair with the distal fascicular turnover flap than with the conventional nerve graft.