Earlier Functional Recovery With an Amniochorionic Membrane Allograft Nerve Wrap After In-Continuity Stretch Injury in the Rat Median Nerve

Introduction:This study investigated the use of an amniochorionic membrane allograft wrap (ACMShield) for treating Epineuroclasis stretch injuries in rat median nerves.Epineuroclasis refers to in-continuity injuries with a disrupted epineurium, identified via load-deformationcurves.Methods: Twenty rats were randomized into three groups: untreated epineuroclasis (n=8), ACMShield-treated epineuroclasis (n=6), and sham-control surgery without injury (n=6).In untreated and ACMShield-treated rats, bilateral median nerves were stretched with a hook until epineuroclasis was observed on load-deformation curves.In treated rats, the ACMShield was wrapped around both injured nerves.Forepaw grip-strength was assessed via the grasping-test pre-injury and at 1, 3, 6, and 9 weeks post-injury.Data were normalized to baseline and analyzed using mixed-effects models.Recovery was defined as reaching a statistically non-significant difference in strength compared to pre-injury baseline strength (p>0.05).Results: Both injury groups lost grip strength at 1 week with 2.00.7% of baseline strength for treated and 3.33.4% for untreated rats (p<0.001).The ACMShield group achieved strength with no statistically detectable difference to baseline at 6 weeks (100.834.6%,p>0.99) and sustained this at 9 weeks (104.533.5%).Untreated rats achieved this later at 9 weeks with 80.929.9% of baseline strength (p=0.34).No difference in percent-of-baseline grip strength was seen between the ACMShield and untreated groups at any postoperative time point. Conclusion:In this pilot study, ACMShield-treated nerves returned to baseline-like grip strength by 6 weeks, whereas untreated nerves returned by 9 weeks.However, between-group comparisons at individual timepoints were not statistically significant, and these findings should therefore be interpreted as exploratory.