Microhook Nerve Connector-Assisted Polyethylene Glycol Fusion for Immediate Restoration of Axon Continuity in a Rodent Model

Purpose

The purpose of the study was to test the efficacy of polyethylene glycol (PEG) fusion in restoring axon continuity when repaired with a microhook nerve connector (MNC) coaptation aid versus conventional microsutures. Our hypothesis was that the MNC would provide precise nerve alignment and stable coaptation and would support a higher percentage of axon fusion.

Methods

In a rodent sciatic nerve model, transected nerves were either repaired with microsutures only (n = 12), microsutures with PEG (n = 12), or a MNC with PEG (n = 12). At initial surgery, PEG fusion was confirmed using electrophysiology. For 3 weeks, gait videos were used to calculate the sciatic function index. At the end of 3 weeks, compound muscle action potentials and muscle strength data were obtained. In a subset of animals, retrograde labeling was performed distal to the repair site and used to confirm successful axon fusion.

Results

Polyethylene glycol fusion was confirmed in all animals from the two PEG groups. At 3 weeks, the sciatic function index values were similar between the three groups. The microsuture-only group did not show any detectable muscle contractions or the presence of intact motor axons. Retrograde labeling demonstrated that partial motor axon continuity had been re-established via PEG fusion in all 8/8 PEG fused animals, muscle contractions were preserved in 13/16, and measurable compound muscle action potentials were recorded in 21/24. However, there were no statistically significant differences between the microsuture + PEG and the MNC + PEG groups.

Conclusions

In a small-diameter, direct-repair rodent model, at least some axons achieved PEG fusion. In this model, a MNC did not seem to improve PEG efficacy over suture-assisted PEG fusion.

Clinical relevance

Polyethylene glycol fusion either performed in conjunction with sutures or a MNC can, to a limited extent, restore axon continuity in cleanly transected, small-diameter nerves.