Neuroma Prevention and Implantation Effects of NEUROCAP in Rat Sciatic Nerve Model

Abstract

Introduction Symptomatic neuroma with neuropathic pain can develop following peripheral nerve injury. Current interventions for symptomatic neuroma have unpredictable results. NEUROCAP (Polyganics, Groningen, The Netherlands) is a bioresorbable nerve capping device intended to protect a peripheral nerve end and separate the nerve from the surrounding environment, to prevent the recurrence of a symptomatic neuroma. Materials and Methods This study aims to assess the implantation effects of the NEUROCAP device in a rat sciatic nerve model during 12 months (±2 days). Forty-one adult male Sprague-Dawley rats were used in this study. They were randomly divided into a capping or test group, or a noncapping or control group for different time points of survival (12 weeks, 6 months, and 12 months). The objective of this study was evaluated regarding procedural data, adverse events, clinical observations, and histopathology. Results The overall general health of the animals was adequate throughout the study, with the exception of autotomy during the first 4 months of survival. Eight animals were euthanized early due to autotomy, excluded from the study and seven of them have been replaced. Autotomy was an expected outcome and a known limitation of the animal model, particularly as this was a full sciatic nerve transection model. Neuroma formation was observed in the control group while there was no neuroma formation present in the test group. The control group showed increased nerve outgrowth and more chaotic fascicles in comparison with the test group. The test group also had a higher percentage of myelinated fibers compared to the control group. These results indicate a preventive mode of action of the NEUROCAP with regard to neuroma formation after nerve transection in a rat sciatic nerve model. Conclusion The results indicate that NEUROCAP is safe and effective in preventing the recurrence of neuroma formation and inhibiting nerve outgrowth.

Surgical Treatment of Symptomatic End-Neuroma With a New Bioresorbable Copolyester Nerve Capping Device

“…Historically, silicone nerve caps were poorly fitted, allowing axon escape, as well as structurally hard and rigid causing secondary neural irritation and the need for unplanned surgical removal 22 . Neurocap is biotolerant and absorbable so that nerve irritation would be unlikely and, if present, would be transient 13 . This was not found to be an issue in the current study, and the revisions reported were not related to device irritation.…”

“…Neurocap, a bioresorbable nerve capping device, was developed to reduce symptomatic neuroma formation by isolating and protecting the peripheral nerve end from the surrounding environment. The design specifically limits sprouting and the disorganized axonal swirling observed in a rodent sciatic neuroma model 13 …”

Development of an acellular nerve cap xenograft for neuroma prevention

“…21,22 Commercially available nerve capping devices made of synthetic or biological degradable materials are intended to provide protection from the tissue injury inflammatory environment. 8,9 While these devices can provide a macrostructural template to contain axonal regeneration, they can also create nerve "compartment syndrome" as they can become a "barrier/trap" for growing/sprouting axons. Furthermore, the degradation products of the synthetic material used for one of these technologies (PLLA-PCA) has been associated with a fibrotic inflammatory response, which can further increase the risk of neuroma formation.…”

“…Commercially available nerve capping devices made of synthetic or biological degradable materials are intended to provide protection from the tissue injury inflammatory environment 8,9 . While these devices can provide a macrostructural template to contain axonal regeneration, they can also create nerve “compartment syndrome” as they can become a “barrier/trap” for growing/sprouting axons.…”

“…These devices can be made of synthetic or biologic materials and appear to attenuate painful neuroma formation, potentially by isolating free sensitized axons. While the cap devices have shown promising results in preclinical studies, 8,9 they have yet to be widely adopted, as the limited clinical evidence available suggests that nerve capping remains inferior to existing surgical approaches 7 . Recent studies have demonstrated that application of an acellular allograft provides a template for termination of the axonal growth potential within the length of the device 10 ; while this approach has shown promise, the length (i.e., 5 cm) of allograft required to exhaust the regenerative potential of the injured nerve creates the need for a more extensive surgical site 11 …”