Characterization of Trimmed Nerve Morphology Using High-Resolution Imaging: Comparison of Three Surgical Instruments.

Purpose: Trimmed proximal and distal nerve stumps should be morphometrically matching and show evidence of healthy fascicular tissue to potentiate nerve regeneration. We hypothesized that differences exist between nerve trimming instruments, providing guidance for optimal nerve-trimming techniques. Methods: Three common surgical instruments were used to trim nerves in three human upper-extremity specimens: a slotted neurotome, a no. 11 surgical blade with a tongue depressor, and super-cut serrated microscissors. Peripheral nerves in flexor tendon zones II and V of the hand were trimmed by surgeons experienced in microsurgery. Microcomputed tomography was used to evaluate the length of damage of the retained nerve stump of trimmed nerves. This damage was measured as the distance from the end of the trimmed nerve to the cross-sectional level with circumferentially intact epineurium and recovered fascicular morphology, which was compared between instruments. The transverse cut end of the nerve was also qualitatively examined using cryoscanning electron microscopy for fascicular distortion and surface roughness. Results: The length of intraneural damage of the proximal and distal nerve stumps was similar between cutting instruments in zone II and in pooled samples (zone II and zone V). In zone V nerve samples, length of intraneural damage was significantly more variable in the scalpel-trimmed samples compared to the neurotome-trimmed and scissor-trimmed samples. Additionally, the cryoscanning electron microscopy images showed that the cut end of nerves trimmed with a scalpel or neurotome had less apparent fascicular distortion and roughness than nerves trimmed with super-cut serrated microscissors. Conclusions: Neurotome-trimmed nerves were the only group that exhibited transverse nerve end surface consistency, smoothness, and less fascicular distortion. We found that use of a surgical blade improves the quality of nerve preparation for repair or reconstruction over the use of super-cut serrated microscissors. Type of study/level of evidence: Basic Science V.