Induced Pseudomembrane Enrichment in Long Nerve Allograft Reconstruction.

Introduction/aims: Long nerve defects are typically reconstructed with autograft or processed acellular nerve allograft (PNA). PNA is convenient and avoids donor morbidity but lacks the neurotrophic environment of autograft. Increased levels of neurotrophic factors have been identified in pseudomembranes induced around silicone implanted between nerve ends. This study aimed to determine if pseudomembrane can be reliably induced around silicone implanted between nerve ends, and if this enhances regeneration of PNA inset within using a staged technique.

Methods: Lewis rats (n = 24) underwent resection of a 15-mm sciatic nerve. The defect was filled with a silicone tube (n = 12) (MA) or the nerve ends were secured to a muscle bed (n = 12) (NMA). After 4 weeks, the silicone was replaced with PNA threaded within the pseudomembrane tunnel. In both groups, PNA was used to reconstruct the nerve defect. Weekly neuromotor assessment was performed with sciatic function index (SFI). At 16 weeks, muscle recovery was assessed, and nerve samples were obtained for histomorphometry.

Results: The MA group's average normalized muscle weight was 46.25% versus the NMA group's 33.19% (p < 0.05). The MA group's average normalized muscle girth was 78.25% versus the NMA group's 60.73% (p < 0.05). Axon counts, g-ratio, and muscle force were not statistically different. At Week 15, the MA group had a significantly higher average SFI: -82.25 versus the NMA group -95.03 (p < 0.05).

Discussion: PNA inset within induced pseudomembrane sheath enhanced muscle reinnervation. A staged membrane enhancement technique may be effective for improving PNA efficacy in peripheral nerve injury reconstruction.