The Effects of a Porcine Extracellular Matrix Nerve Wrap as an Adjunct to Primary Epineurial Repair

Outcomes after end-to-end epineural suture repair remain poor. Nerve wraps have been advocated to improve regeneration across repair sites by potentially reducing axonal escape and scar ingrowth; however, limited evidence currently exists to support their use. Forty Lewis rats underwent median nerve division and immediate repair. Half were repaired with epineural suturing alone, and the others underwent epineural suture repair with the addition of a nerve wrap. Motor recovery was measured using weekly grip strength and nerve conduction testing for 15 weeks. Histomorphometric analyses were performed to assess intraneural collagen deposition, cellular infiltration, and axonal organization at the repair site, as well as axonal regeneration and neuromuscular junction reinnervation distal to the repair site. The wrapped group demonstrated significantly less intraneural collagen deposition at 5 weeks. Axonal histomorphometry, cellular infiltration, neuromuscular junction reinnervation, and functional recovery did not differ between groups. Nerve wraps reduced collagen deposition within the coaptation; however, no differences were observed in axonal regeneration, neuromuscular junction reinnervation, or functional recovery. These findings suggest that extracellular matrix nerve wraps can attenuate scar deposition at the repair site. Any benefits that may exist with regards to axonal regeneration and functional recovery were not detected in our model.