Regeneration through Nerve Isografts is Independent of Nerve Geometry

Abstract

Investigators have theorized that tortuosity in nerve grafts may adversely affect nerve regeneration. This study investigated the effect of graft configuration and redundancy on regeneration across 2.5-cm rat sciatic nerve isografts. Thirty-two Lewis rats were randomized to four nerve grafting groups defined by gap distance and isograft conformation. In Group 1, grafts were interposed into a 2-cm gap, resulting in mild graft redundancy. In Groups 2 and 3, grafts were tacked in sinusoidal or omega-shaped configurations, respectively, to bridge a 0.5-cm gap. In Group 4, grafts were interposed after 1 cm of native sciatic nerve was resected, resulting in no graft redundancy and an interstump distance of 2.5 cm. At 6 weeks, nerve tissue was harvested; subsequent histomorphometric analysis revealed no significant differences in regeneration between groups. These data suggest that regeneration through isografts is independent of the graft geometry and redundancy.

Effect of Motor versus Sensory Nerve Autografts on Regeneration and Functional Outcomes of Rat Facial Nerve Reconstruction

“…A subsequent study demonstrated no differences at the 3-week time-point in analyzing myelinated axon counts between sensory, motor, and mixed (both motor and sensory components) autografts in a mixed nerve defect model 26 . Similarly, a large-scale study in 100 rats demonstrated equivocal results in motor, sensory, mixed nerve grafts via histomorphometric analysis at 5, 6, and 7 weeks in the tibial nerve model 27 . A potential shortcoming to the studies that demonstrated motor isograft superiority is the early endpoint, with histomorphometric analyses at three weeks after reconstruction 18,19 .…”

Nerve stepping stone has minimal impact in aiding regeneration across long acellular nerve allografts

“…The grafted nerves need to loop and insert into an under‐the‐skin “pocket” around the femur requiring the nerve ends to remain their original length after transection . The sigmoidal nature of this path does not interfere with regeneration . To provide control ANAs (6 cm), a 1‐cm ANA was coapted between two 2.5‐cm ANAs.…”

“…11 The sigmoidal nature of this path does not interfere with regeneration. 33 To provide control ANAs (6 cm), a 1-cm ANA was coapted between two 2.5-cm ANAs. Control ANAs contained a short ANA (1 cm) between two 2.5-cm ANAs rather than a single long (6 cm) ANA to control for possible suture line effects.…”

The effects of venous ensheathment on facial nerve repair in the rat

“…Peripheral nerve injuries are common, with overall incidence standing at 6,250 per 100 thousand in the United States alone . Currently, research effort principally has been directed at improving functional outcome and regeneration accuracy of axons following neural anastomosis or grafting . Some studies suggested that isolation of the regenerating milieu, via ensheathment with autologous, biological, or synthetic materials, could promote axonal regeneration and improve functional outcome.…”

“…Some studies suggested that isolation of the regenerating milieu, via ensheathment with autologous, biological, or synthetic materials, could promote axonal regeneration and improve functional outcome. Among the variables investigated, fascicular alignment, suture type, location, techniques, neurorrhaphy orientation, and tension have been exhaustively studied to determine the optimal neurorrhaphy methods . Tensionless repair, introduction of viable Schwann cells, and delivery of certain neurotrophic agents only had modest recovery benefits .…”