Use of poly dl-lactide-ε-caprolactone (Neurolac) conduit for enveloping traumatic neuromas

Targeted muscle reinnervation in managing post-amputation related pain: A systematic review and meta-analysis

INTRODUCTION

Limb amputation can cause residual limb pain (RLP) and/or phantom limb pain (PLP). Although targeted muscle reinnervation (TMR) was initially introduced to facilitate the control of prosthetic limbs, it has been noted that these patients experience less pain and improved prosthetic functional outcomes. As a result, the use of TMR in managing neuroma-related RLP is increasing. The aim of this review is to assess the quality and strength of the evidence supporting the effectiveness of TMR in managing amputation-related pain.

METHODS

Five different databases, including MEDLINE (PubMed), Scopus, Web of Science, Cochrane Library, and Embase, were searched from inception to March 2022. The protocol for this systematic review has been registered in the PROSPERO database (CRD42020218242). To be included, studies needed to compare pre- and postoperative pain outcomes or different techniques for adult patients who underwent TMR following amputation. Eligible studies also needed to use patient-reported outcome measures (PROMS) and be clinical trials or observational studies published in English. Excluded studies were case reports, case series, reviews, proof of concept studies, and conference proceedings. A meta-analysis was performed on studies that had similar intervention and control groups to examine treatment effects using a random-effects model. Studies were weighted using the inverse variance method, and a statistically significant p-value was considered to be less than or equal to 0.05.

RESULTS

This review included five studies for qualitative analysis and four studies for quantitative analysis. Reviewed studies enrolled a total of 127 patients. The TMR group was compared with standard treatment at 12 months follow-up. The TMR group showed significantly better PLP as assessed by the numerical rating score RLP, and PLP assessed using Patient-Reported Outcomes Measurement Information System (PROMIS) also showed significantly lower pain intensity in the TMR group.

CONCLUSION

There is limited evidence of good quality favoring TMR in reducing postamputation PLP and RLP pain compared with standard care. Randomized clinical trials are encouraged to compare the efficacy of different surgical techniques.

Surgical Treatment of Symptomatic End-Neuroma With a New Bioresorbable Copolyester Nerve Capping Device: A Multicenter Prospective Cohort Study

BACKGROUND

Neuroma-induced neuropathic pain is associated with loss of function and reduced quality of life. No consistently effective standard-of-care treatment has been defined. Neurocap, a bioresorbable nerve capping device, has been designed to isolate the nerve stump from surrounding tissues to reduce development of symptomatic end-neuromas.

METHODS

Patients with peripheral symptomatic end-neuromas were included in a prospective, multicenter, single-arm design. Data were collected presurgery up till 24 months postsurgery. Eligible patients with neuromas were identified based on blocks using anesthetic. Intervention included surgical excision and capping of the transected proximal nerve end with the Neurocap. Main outcome measures were pain, function, recurrence of symptomatic neuroma, use of analgesics, and adverse events.

RESULTS

In total, 73 patients with 50 upper-extremity and 23 lower-extremity end-neuromas were enrolled. End-neuromas were predominately located in the digits and lower leg. Statistical power of the study outcomes was preserved by 46 of 73 patients completing 24-month follow-up. The mean VAS-Pain score at baseline was 70.2 ± 17.8 (scale 0-100) and decreased significantly to 31 ± 32.5 (P < 0.001). Function significantly improved over time. The recurrence rate of confirmed symptomatic neuroma was low (2 of 98 capped nerves). Adverse event rate was low and included pain and infection; there were no unexpected device-related adverse events. Most patients reported lower use of nonsteroidal anti-inflammatory drugs, opioids, and antineuropathic medications at last follow-up compared with baseline.

CONCLUSIONS

End-neuroma treatment with excision and capping resulted in long-term significant reduction in reported pain, disability, and analgesic medication use. Adverse event rate was low.

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

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.

An aligned nanofiber nerve conduit that inhibits painful traumatic neuroma formation through regulation of the RhoA/ROCK signaling pathway

OBJECTIVE

Traumatic neuromas represent a prevalent source of neuropathic pain. As of yet, there has been no single treatment method that can guarantee permanent relief of symptoms. Although nerve-capping techniques have shown promise, their exact mechanisms remain elusive. The authors' aim was to examine the role of the RhoA/ROCK signaling pathway in the prevention of neuroma formation after neurectomy utilizing a nerve-capping technique.

METHODS

An aligned nanofiber tube was fabricated to cap the sciatic nerve in Sprague Dawley rats. The rats (n = 60) were randomly divided into the aligned SF/P (LLA-CL) capping group (capping group, n = 20), the capping and Y-27632 (ROCK pathway inhibitor) intervention group (intervention group, n = 20), and the no-capping group (control group, n = 20). The authors undertook a comprehensive assessment of the capping group, examining the animals' behavior, the extent of neuroma development, histology, gene and protein expression, and ultrastructural changes associated with the RhoA/ROCK signaling pathway. These findings were compared with those in the intervention and control groups.

RESULTS

The inciting injury resulted in the expression of the RhoA/ROCK signaling pathway, as well as its further upregulation in peripheral neurons. Axon outgrowth was significantly increased when RhoA/ROCK signaling pathway was suppressed. The average autotomy score in the capping group was observed to be much lower than that of the intervention and control groups. At 30 days postneurectomy, the capping group displayed no obvious neuroma formation, while a bulbous neuroma was found in the nerve stumps of both the control and intervention groups. Quantitative real-time polymerase chain reaction and the Western blot analysis demonstrated that the expression of myelin-associated glycoprotein was substantially upregulated in the capping group; in contrast, the expression of NF-200 was significantly downregulated. The expression of myosin light chain was notably lower in the intervention group, but there was no significant difference when compared with the control group (p > 0.05).

CONCLUSIONS

The RhoA/ROCK signaling pathway has emerged as a critical player in the process of traumatic neuroma formation after neurectomy. It is possible that the nerve-capping technique could generate a "regenerative brake" based on the regulation of the RhoA/ROCK signaling pathway in this event. These findings may provide concrete evidence that could help develop new strategies for the management of painful neuromas.