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Evaluating the Safety of a Novel Nerve Coaptation Device as a Suture-Less Alternative for Repairing Peripheral Nerve Defects
Geetanjali S Bendale, PhD1; Lida Daniel, BS1; Matt Smith, MD1; Isabelle deBruler, BS1; Mariana Gragnani, BS1; Ryan Clement, PhD2; Jules McNeice, MS2; Fletcher Griffitts, MS2; Maximilian Sonntag, MS2; Jack Griffis, MS2; Isaac Clements, PhD2; Jonathan Isaacs, MD3
1Virginia Commonwealth University, Richmond, VA; 2BioCircuit Technologies, Atlanta, GA; 3Department of Orthopaedics, Virginia Commonwealth University, Richmond, VA

Introduction: Microsuture neurorrhaphy, the clinical gold standard for peripheral nerve repair, suffers from imprecise alignment and requires advanced microsurgery skills. Conduit-assisted repairs may improve alignment but can still be technically challenging. We developed a suture-less nerve coaptation device, Nerve Tape®, composed of Nitinol microhooks embedded within a porcine small intestine sub-mucosa backing. These tiny microhooks engage the superficial nerve tissue while the backing entubulates the coaptation to provide a secure and well-aligned repair. Engaging through the outer epineurium is the expected mode of action for both microhooks and microsutures and necessary for a secure attachment. Though designed specifically to maximize tissue hold while minimizing tissue damage, the potential risk of the microhooks penetrating nerve fascicles and axons needed to be assessed.
Materials and Methods: Eighteen male New Zealand White rabbits underwent a tibial nerve transection immediately repaired with either 1) Nerve Tape, 2) conduit (AxoGuard Nerve Connector®) or 3) four circumferential 9-0 nylon microsutures. At sixteen weeks post-injury, the nerves were re-exposed to score for gross morphology and perform nerve tissue histology. Tissue was post-fixed in 4% paraformaldehyde, embedded in paraffin, and thin 12µm sections were obtained. A set of slides proximal, at coaptation, and distal to coaptation were stained using Masson’s Trichrome and immunohistochemistry (IHC). For IHC, slides were labelled with NF-200 for axons, P0 for myelin, MAC387 for macrophages, and DAPI for cell nuclei. Low magnification brightfield images were evaluated for collagen quality and to identify microhook and microsuture penetration points. High magnification confocal images of identified microhooks and microsutures were used to evaluate the surrounding axon density, cellular density, and macrophages.
Results: The collagen quality and thickness were similar between the groups. As expected, microhooks were seen to penetrate through the outer epineural tissue, but none of the microhooks appeared to penetrate the perineurial layer surrounding individual fascicles. Microhooks maintained an average 108µm distance from inner fascicles. Although within similar proximity, suture material was also found to be present deep within nerve fascicles, in both the conduit and microsuture groups. IHC images showed a similar density of axons and cells surrounding microhooks and microsuture materials, indicating a similar tissue response.
Conclusion: There does not appear to be increased morbidity associated with Nerve Tape nerve repair as compared with conventional suture and conduit-assisted nerve repairs.


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