Prevention of Neuromas with a Porcine SIS Nerve Cap: A Histopathologic Evaluation
Shahryar Tork, MD1; Jennifer Faleris, BS2; Anne Engemann, PhD2; Curt Deister, PhD2; Erick DeVinney, BS2; Ian L. Valerio, MD, MS, MBA1
1Department of Plastic Surgery, The Ohio State University, Wexner Medical Center, Columbus, OH; 2AxoGen, Alachua, FL
Introduction Following traumatic or oncologic nerve amputations, the aberrant axonal regeneration may result in painful neuroma formation. Studies suggest that isolating the nerve-end within a protective cap at the time of amputation or revision procedures may assist in the prevention of nerve-end neuromas. New nerve capping techniques, such as with novel porcine small intestine submucosa (SIS) nerve caps, may lead to improved neuroma management strategies. This study evaluated the local effects of two Nerve Caps (NC) with internal chambering (Partition or Spiral) on a terminal nerve end.
Materials & Methods The tibial nerves of fifty-seven (57) male Sprague Dawley rats were dissected, ligated, transected and trans-positioned to the lateral hindleg. The nerves were either treated with a Nerve Cap Spiral (NCs), Nerve Cap Partition (NCp) or Open Tube (OT), alternatively surgical control (SC) nerve stumps were non-treated. The nerve caps contained internal chambering within an enclosed structure. The animals were euthanized at 8 and 12 weeks. Tissues samples were explanted, sectioned longitudinally, and stained with Hematoxylin and Eosin (HE), Masson's Trichrome (MT), or Neurofilament 200 (NF 200). Slides were analyzed for axonal swirling, nerve width, cap remodeling and overall tissue response.
Results Both the SC and OT groups had significantly higher scores for axonal swirling compared to the NC groups, which showed no identifiable axonal swirling (p=0.02 and 0.03, respectively). Nerve widths were notably wider in SC groups compared to NC groups. Overall, the inflammation and tissue responses in the NC and OT groups were similar at both time points and were considered non-irritants. On average, the inflammation at 8 weeks was highest in the NCp group, followed by the NCs and OT groups, and lowest in the SC group. By 12 weeks, the average inflammation was highest in the OT group, followed by the NCs group, and lowest in the NCp and SC groups. There was minimal to mild resorption in the NC and OT groups at 12 weeks as compared to the baseline material evaluated at 8 weeks.
Conclusion The investigational porcine SIS nerve caps effectively decreased axonal swirling and distal nerve diameters within a rodent neuroma model. The internal chambering within the nerve caps allowed axons to be dispersed, aligned, and mitigated in an enclosed microenvironment. This study suggests that nerve caps with internal chambering for axonal outgrowth may leverage the limitations of conduits and improve axonal alignment, therefore reducing the likelihood of symptomatic neuroma formation.
Back to 2018 ePosters