surgery-behavioral-testing-tibial-neuroma-transposition-model

Surgery and Behavioral Testing in the Tibial Neuroma Transposition Model in Rats

The tibial neuroma transposition (TNT) is a rat model in which allodynia at the neuroma site (tibial nerve) can be independently evaluated from allodynia ...

Axogen

Peripheral nerve repair can be very rewarding for both surgeon and patient when expected outcomes are achieved. In many cases, however, the results are suboptimal due to number of possible objective and technical reasons. Although we cannot influence patent's comorbidities, the extent or mechanism of the nerve injury, we may help optimize technical details when aiming towards improved outcomes. While the suture coaptation for primary nerve repair or nerve reconstruction with grafting served as the reconstructive standard for many decades, technical imperfections remain threats to reconstructive goals. Tension, fascicular misalignment generated by over tightening suture coaptation, deeply placed sutures, reactive scarring to foreign material at anastomosis site, may all negatively affect axonal regeneration. As the goal of every nerve repair is to have ideally opposed tension free nerve fascicles, protected from the deleterious effects of the wound bed. The utilization of coaptation aids to overcome the challenges of nerve repair has been suggested as an alternative to the classical suture repair. A review of clinical literature was performed to assess the evidence for this technique and the critical success factors to consider when implementing this technique. Twelve clinical studies met criteria, majority suggesting improved outcomes by the utilization of a coaptation aid. Most commonly reported improvements were improved sensory outcomes, reduced tenderness or pain at the coaptation site and reduced operative time. The current clinical evidence data suggests that utilization of a coaptation aid is a technical innovation to help provide better nerve repair and reconstructive functional outcomes.

Refinements of nerve repair with connector-assisted coaptation.

Painful neuroma formation is a common and debilitating sequela of traumatic or oncologic nerve amputations. Studies suggest that isolating transected nerve stumps within protective caps during amputation surgery or revision procedures may assist in preventing symptomatic nerve-end neuroma formation. This study evaluated the local effects of two porcine small intestine submucosa (pSIS) nerve caps of differing configurations on a terminal nerve end in an animal model. The tibial nerves of 57 Sprague Dawley rats were transected and transposed to the lateral hind leg. The nerves were treated with one of three SIS materials, including (i) a nerve cap with spiraling chambering, termed spiral nerve cap (SNC), (ii) a nerve cap with bifurcated chambers termed chambered nerve cap (CNC), or (iii) an open tube. The surgical control consisted of nerve stumps that were not treated. Overall tissue response, axonal swirling, optical density of axons, and behavioral pain response were quantified at 8 and 12 weeks postoperatively. There were no notable differences between the performance of the SNC and CNC groups. The pSIS nerve caps mitigated aberrant axonal regeneration and decreased neuroma formation and associated pain response. These findings suggest that nerve caps with internal chambers for axonal outgrowth may improve axonal alignment, therefore reducing the likelihood of symptomatic neuroma formation. Impact statement This study provides evidence for using nerve caps with internal structure on nerve stumps after amputation surgeries to reduce or prevent symptomatic neuromas. This study showed that porcine small intestine submucosa had a favorable remodeling profile and tissue response, illustrating that this device can be used to (i) minimize soft tissue attachments around the nerves that are capped, (ii) align axonal outgrowth to guide nerve regeneration away from aberrant neuroma formation, and (iii) act as a barrier between the nerve and external stimuli ultimately remodeling into a new soft tissue layer around the nerve stump thus decreasing symptomatic neuroma formation.

Application of a Porcine Small Intestine Submucosa Nerve Cap for Prevention of Neuromas and Associated Pain.

Neuropathic pain caused by adhesions or neuroma formation of the superficial branch of the radial nerve (SBRN) is difficult to treat. The authors evaluated the effectiveness of different routinely used surgical techniques for SBRN neuralgia to provide a basis for future studies on SBRN neuralgia and explored the prognostic value of a preoperative diagnostic nerve block.

Erick DeVinney

Axogen

Surgery and Behavioral Testing in the Tibial Neuroma Transposition Model in Rats