Nerve Transection Repair Using Laser-Activated Chitosan in a Rat Model

Objectives/Hypothesis: Cranial nerve transection during head and neck surgery is conventionally repaired with microsuture. Previous studies have demonstrated recovery with laser nerve welding (LNW), a novel alternative to microsuture. LNW has been reported to have poorer tensile strength, however. Laser-activated chitosan, an adhesive biopolymer, may promote nerve recovery while enhancing the tensile strength of the repair. Using a rat posterior tibial nerve injury model, we compared four different methods of nerve repair in this pilot study. Study Design: Animal study. Design: Animals underwent unilateral posterior tibial nerve transection. The injury was repaired by potassium titanyl phosphate (KTP) laser alone (n - 20), KTP + chitosan (n - 12), microsuture + chitosan (n - 12), and chitosan alone (n - 14). Weekly walking tracks were conducted to measure functional recovery (FR). Tensile strength (TS) was measured at 6 weeks. Results: At 6 weeks, KTP laser alone had the best recovery (FR = 93.4% +/- 8.3%). Microsuture + chitosan, KTP + chitosan, and chitosan alone all showed good FR (87.4% +/- 13.5%, 84.6% +/- 13.0%, and 84.1% +/- 10.0%, respectively). One-way analysis of variance was performed (F(3,56) = 2.6, P = .061). A TS threshold of 3.8 N was selected as a control mean recovery. Three groups-KTP alone, KTP + chitosan, and microsuture 1+chitosan-were found to meet threshold 60% (95% confidence interval [CI]: 23.1%-88.3%), 75% (95% CI: 46.8%-91.1%), and 100% (95% CI: 75.8%-100.0%), respectively. Conclusions: In the posterior tibial nerve model, all repair methods promoted nerve recovery. Laser-activated chitosan as a biopolymer anchor provided good TS and appears to be a novel alternative to microsuture. This repair method may have surgical utility following cranial nerve injury during head and neck surgery.