Use of human amniotic membrane wrap in reducing perineural adhesions in a rabbit model of ulnar nerve neurorrhaphy.

The object of this experimental study was to assess the effect of wrapping human amniotic membrane around a repaired ulnar nerve in a rabbit model of perineural adhesion. Ulnar nerves from 10 white New Zealand rabbits were exposed bilaterally, dissected and repaired. Human amniotic membrane was then wrapped around the repair site in one limb with no such wrap in the neurorrhaphy of the contralateral limb. Three months later, the same nerves were re-explored and removed using microsurgical external neurolysis. Perineural adhesion around the ulnar nerve was evaluated by blinded surgical dissection and scored using a visual 4-point qualitative scale. Extent and grade of fibrosis around repair sites were measured microscopically (x 200) after Masson trichrome staining using measure of the depth of fibrosis and the grading criteria of adhesion. Quantitative morphometric analysis was also performed under light microscopy (x 200) with the aid of a digital counter and virtual slide imaging software (ScanScope T2, Vista, CA, USA). Human amniotic membrane wrapped nerves showed significantly less perineural adhesion and fibrosis than controls (P < 0.05). No nerve healing problems were encountered. This study suggests that human amniotic membrane application can reduce fibrosis and adhesion around neurorrhaphy sites in this animal model.