Use of collagen conduits in management of painful neuromas of the foot and ankle

Nerve Capping Techniques for Neuroma Management: A Comprehensive Literature Review

BACKGROUND/AIM OF THE STUDY

Nerve capping is a method of neuroma treatment or prevention that consists of the transplantation of a proximal nerve stump into an autograft or other material cap, after surgical removal of the neuroma or transection of the nerve. The aim was to reduce neuroma formation and symptoms by preventing neuronal adhesions and scar tissue. In this narrative literature review, we summarize the studies that have investigated the effectiveness of nerve capping for neuroma management to provide clarity and update the clinician's knowledge on the topic.

METHODS

A systematic electronic search following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria was performed in the PubMed database combining "neuroma," "nerve," "capping," "conduit," "treatment," "management," "wrap," "tube," and "surgery" as search terms. English-language clinical studies on humans and animals that described nerve capping as a treatment/prevention technique for neuromas were then selected based on a full-text article review. The data from the included studies were compiled based on the technique and material used for nerve capping, and technique and outcomes were reviewed.

RESULTS

We found 10 applicable human studies from our literature search. Several capping materials were described: epineurium, nerve, muscle, collagen nerve conduit, Neurocap (synthetic copolymer of lactide and caprolactone, which is biocompatible and resorbable), silicone rubber, and collagen. Overall, 146 patients were treated in the clinical studies. After surgery, many patients were completely pain-free or had considerable improvement in pain scores, whereas some patients did not have improvement or were not satisfied after the procedure. Nerve capping was used in 18 preclinical animal studies, using a variety of capping materials including autologous tissues, silicone, and synthetic nanofibers. Preclinical studies demonstrated successful reduction in rates of neuroma formation.

CONCLUSIONS

Nerve capping has undergone major advancements since its beginnings and is now a useful option for the treatment or prevention of neuromas. As knowledge of peripheral nerve injuries and neuroma prevention grows, the criterion standard neuroprotective material for enhancement of nerve regeneration can be identified and applied to produce reliable surgical outcomes.

Revision Surgery for Recurrent Morton Neuroma with Use of a Collagen Conduit

Background

Painful neuromas of the foot and ankle frequently pose a treatment dilemma because of persistent pain or recurrence after resection. Primary surgical treatment of painful neuromas includes simple excision with retraction of the residual nerve ending to a less vulnerable location1-4. The use of a collagen conduit for recurrent neuromas is advantageous, particularly in areas with minimal soft-tissue coverage options, and is a technique that has shown 85% patient satisfaction regarding surgical outcomes7. Additionally, the use of a collagen conduit limits the need for deep soft-tissue dissection and reduces the morbidity typically associated with nerve burial.

Description

Specific steps include appropriate physical examination, preoperative planning, and supine patient positioning. The patient is placed supine with a lower-extremity bolster under the ipsilateral extremity in order to allow improved visualization of the plantar surface of the foot. A nonsterile tourniquet is placed on the thigh. The incision site is marked out, and a longitudinal plantar incision is made until proximal healthy nerve is identified-typically approximately 1 to 2 cm, but the incision can be extended up to 6 cm. The incision is made between the metatarsals, with blunt dissection carried down to the neuroma. The neuroma is sharply excised distally through healthy nerve, and a whip stitch is placed to facilitate the collagen conduit placement. The collagen conduit is passed dorsally into the intermetatarsal space and secured to the dorsal fascia of the foot. The wound is closed with 3-0 nylon horizontal mattress sutures. Postoperatively, a soft dressing is applied to the operative extremity, and patients are advised to be non-weight-bearing for two weeks. At two weeks, patients begin partial weight-bearing with use of a boot, and physical therapy is initiated. No antibiotics are necessary, and 300 mg of gabapentin is prescribed and tapered off by the six-week follow-up visit. Follow-ups are conducted at 2, 6, 12, 24, and fifty-two weeks. It is necessary to monitor for signs and symptoms of infection, surgical complications, and neuroma recurrence during follow-up appointments.

Alternatives

Simple excision of the neuroma with proximal burial into muscle or bone is a common surgical technique. However, inadequate resection of the nerve or poor surgical technique can lead to recurrent neuromas. For neuromas not responding to simple excision, other techniques have been utilized, including cauterization, chemical agents, nerve capping, and muscle or bone burial5,6. The results of these techniques have varied, and none has gained clinical superiority over the other6.

Rationale

A study analyzing the use of collagen conduits for painful neuromas of the foot and ankle has shown this technique to be a safe and successful alternative to the previously discussed methods of resection7. That study by Gould et al. found that 85% of patients had a substantial reduction in pain, with mean visual analog scale (VAS) pain scores reducing from 8 to 10 preoperatively to 0 to 4 postoperatively7. Moreover, alternative biological conduits, such as the greater saphenous vein, have proven to be costly in time and resources, as this structure is often utilized in cardiovascular bypass surgery and its harvest conveys a risk of iatrogenic nerve injury to the patient7.Numerous studies focusing on excision of recurrent Morton neuromas via a plantar approach have found variable success rates. Of the patients surveyed in those studies, 75% reported substantial pain improvement. However, <50% of these queried patients reported complete pain relief8,9. Studies analyzing the dorsal approach for revision Morton neuroma excision found similar success rates. Approximately 78% of patients reported good or excellent postoperative outcomes, and significant improvements were observed in patient postoperative Patient-Reported Outcomes Measurement Information System (PROMIS) scores for pain interference, intensity, and global physical health10,11. One study comparing outcomes following plantar versus dorsal approaches for recurrent Morton neuroma found no significant difference in postoperative patient outcomes. That study suggested that surgeons utilize the approach with which they are most comfortable12. Gould et al. reported an 85% success rate with collagen conduit, which was similar to if not slightly improved compared with the other prior studies. The utilization of a collagen conduit technique thus offers comparable patient outcomes for patients with difficult neuromas7.

Expected Outcomes

Recurrent neuroma resection with the use of a collagen conduit has proven to provide satisfactory patient outcomes regarding pain and neuritis symptoms7. The goal of any neuroma resection is to greatly diminish or entirely eliminate nerve pain. Based on the available evidence, there has been no proven clinical superiority of any particular technique over the others6. However, in the present example case, the location of the patient's neuroma in this video makes it 85% likely that the patient will report satisfactory outcomes and 50% likely that the patient will be entirely symptom-free7. At two weeks postoperatively, the patient reported well controlled pain, absence of burning or tingling sensation, full range of movement in the foot, and intact sensation throughout all major nerve distributions, including the saphenous; superficial peroneal nerve; deep peroneal nerve; and sural, medial, and lateral plantar nerves. However, sensation is absent distal to the site of a neuroma resection.

Important Tips

Careful preoperative planting is of utmost importance.Ruling out other potential pathologies is necessary to ensure proper outcomes.Meticulous dissection should be carried out, with delicate handling of the proximal nerve ending.Excision of the nerve should be done sharply through the healthy portion of the nerve.Appropriate sizing of the nerve conduit (with a commercially available industry sizer) should be performed.The nerve conduit should be passed dorsally and secured to the dorsal fascia without any tension.

Acronyms and Abbreviations

MRI = magnetic resonance imagingUS = ultrasoundVAS = visual analog scale.

Addition of a Vascular Bundle Accelerates Bone Union in Femoral Bone Defects

BACKGROUND

 The Masquelet method has become increasingly popular for the treatment of bone defects in recent years. In this method, an induced membrane (IM) with abundant blood circulation, stem cells, and osteogenesis-promoting factors is formed by implanting bone cement during the first surgery. This IM stimulates bone formation in the bone defect after implantation of the bone graft during the second surgery. However, the Masquelet method requires two surgeries and thus a longer treatment period. In the present study, we investigated whether bone defects could be reconstructed in a single surgery by introducing a vascular bundle into the bone defect as an alternative to the IM, in addition to bone grafting.

METHODS

 Thirty-six 12-week-old female Sprague-Dawley rats were used. After creating a 5-mm long bone defect in the femur, a mixture of autologous and artificial bone was grafted into the defect, and a saphenous arteriovenous vascular bundle was introduced. The animals were divided into three groups: the control group (bone defect only), the BG group (bone grafting only), and the BG + V group (bone grafting + vascular bundle introduction). After surgery, radiological and histological evaluations were performed to assess osteogenesis and angiogenesis in bone defects.

RESULTS

 In the BG + V group, significant bone formation was observed in the bone defect on radiological and histological evaluations, and the amount of bone formation was significantly higher than that in the other two groups. Furthermore, cortical bone continuity was observed in many specimens in the BG + V group. On histological evaluation, the number of blood vessels was also significantly higher in the BG + V group than in the other two groups.

CONCLUSION

 Our results suggest that the introduction of a vascular bundle in addition to bone grafting can promote bone formation in bone defects and allow for complete bone defect reconstruction in a single surgery.

Nerve-End Capping Treatment with a Polyglycolic Acid Conduit for Rat Sciatic Neuroma: A Preliminary Report

BACKGROUND

 The treatment of painful neuroma remains challenging. Recently, a nerve-end capping technique using a bioabsorbable nerve conduit was newly introduced to treat amputation neuroma. A collagen-coated polyglycolic acid (PGA) conduit has been commercially available for the reconstruction of peripheral nerve defects, yielding successful clinical outcomes. However, no experimental research has been conducted using this PGA nerve conduit as capping device for treating amputation neuroma. The purpose of this study was to investigate nerve-end capping treatment with the PGA conduit in the rat sciatic nerve amputation model, focusing on histological scar formation and neuroinflammation.

METHODS

 Forty-seven rats were divided into two groups: no capping (transected nerve stump without capping; n = 25) and capping (nerve-end capping with collagen-coated PGA nerve conduit; n = 22). Twelve weeks after sciatic neurectomy, neuropathic pain was evaluated using the autotomy score. Stump neuromas were histologically evaluated or perineural scar and neuroinflammation.

RESULTS

 While autotomy scores gradually exacerbated in both groups, they were consistently lower in the capping group at 4, 8, and 12 weeks postprocedure. Twelve weeks after surgery, the transected nerve stumps in the no-capping group had formed macroscopic bulbous neuromas strongly adhering to surrounding tissues, whereas they remained wrapped with the PGA nerve conduits loosely adhering to surrounding tissues in the capping group. Histologically, distal axonal fibers were expanded radially and formed neuromas in the no-capping group, while they were terminated within the PGA conduit in the capping group. Perineural scars and neuroinflammation were widely found surrounding the randomly sprouting nerve end in the no-capping group. In capped counterparts, scars and inflammation were limited to closely around the terminated nerve end.

CONCLUSION

 Nerve-end capping with a collagen-coated PGA conduit after rat sciatic neurectomy might prevent neuroma formation by suppressing perineural scar formation and neuroinflammation around the nerve stump, potentially relieving neuropathic pain.

Complications of Hallux Rigidus Surgery

Hallux rigidus can be treated with a variety of surgical procedures, including joint preserving techniques, arthrodesis, and arthroplasty. The most commonly reported complications for joint preserving techniques consist of progression of arthritis, continued pain, and transfer metatarsalgia. Although good outcomes have been reported for arthrodesis overall, careful attention must be paid to technique and positioning of the toe to avoid nonunion or malunion. Arthroplasty preserves motion but in the case of failure can present the additional challenge of bone loss. In these scenarios, the authors recommend distraction bone block arthrodesis with structural autograft.

Nerve capping treatment using a bioabsorbable nerve conduit with open or closed end for rat sciatic neuroma

BACKGROUND AND AIMS

Nerve capping treatment using bioabsorbable nerve conduits has recently been introduced for painful amputation neuroma. However, no clinical or experimental data are available for comparing nerve conduits with open distal ends and closed distal ends. Here, we investigated the nerve conduit with open or closed distal ends as the superior capping device, using a commercially available polyglycolic acid (PGA) nerve conduit in a rat sciatic nerve amputation model.

METHODS

Ninety-one rats were assigned to three groups: no-capping (n = 30), capping the resected nerve stump with open ends (n = 31), and closed-end nerve conduits (n = 30). Twelve weeks after sciatic neurectomy, with or without capping, the evaluation of neuropathic pain using the autotomy score was performed. Stump neuromas with perineural scars and neuroinflammation were evaluated histologically.

RESULTS

The mean autotomy scores in the closed-end nerve conduit group were significantly lower than those in the no-capping group. However, the difference between the open-end nerve conduit and the closed-end nerve conduit groups was insignificant. Histologically, distal axonal fibers expanded radially and formed neuromas in the no-capping group while they were terminated within the PGA conduit in both capping groups. In particular, the closed-end version of the PGA nerve conduit blocked scarring from intruding through the open end and protected the nerve stump with less neuroinflammation. Nerve capping with the closed-end version of the PGA nerve conduit most effectively suppressed perineural neuroinflammation and scar formation around the resected nerve stump.

INTERPRETATION

Nerve capping with the PGA nerve conduit, particularly those with closed ends, after rat sciatic neurectomy prevented amputation neuroma and relieved neuropathic pain.

Revision of Recurrent Neuromas

Forefoot neuromas are a common pathology that is seen in a wide variety of patients. Although conservative treatment is successful with modification of shoes/inserts or injections, surgical intervention is occasionally needed to alleviate the discomfort. Most surgical procedures for neuromas have a good outcome. There are times when the outcome is not optimal and revision surgery may be needed. This article describes revision surgery techniques that may lead to an improved outcome. Also discussed is the opportunity to reduce recurrence through the understanding of neuroma biology, diagnosis, and treatment options.

Neurocap Use for the Treatment of Iatrogenic Neuropathic Pain: Preliminary Operative Results in 3 Patients

Painful neuromas are a devastating condition that is notoriously difficult to treat. The large number of techniques that have been attempted suggest that no one technique is superior. Neuromas often occur in the extremities, but iatrogenically caused pain in the head and neck area has also been described. This article describes 3 consecutive patients diagnosed with traumatic neuroma who underwent transection of the causative nerve, followed by capping of the nerve stump with a Neurocap. With a follow-up of 7 to 24 months, our results show a marked reduction in the pain scores of all 3 patients. The preliminary results indicate that this technique might be a viable treatment option for patients with a suspected neuroma in the head and neck area.

Nerve capping with a nerve conduit for the treatment of painful neuroma in the rat sciatic nerve

OBJECTIVE

Treatment of painful neuroma remains difficult, despite the availability of numerous surgical procedures. Recently, nerve capping treatment for painful neuroma using artificial nerve conduits has been introduced in clinical and basic research. However, the appropriate length of the nerve conduit and the pain relief mechanism have not been determined. In this study the authors aimed to investigate nerve capping treatment with a bioabsorbable nerve conduit using the rat sciatic nerve amputation model. Using histological analysis, the authors focused on the nerve conduit length and pain relief mechanism.

METHODS

Sixteen Sprague Dawley rats were evaluated for neuropathic pain using an autotomy (self-amputation) score and gross and histological changes of the nerve stump 2, 4, 8, and 12 weeks after sciatic nerve neurectomy without capping. Forty-five rats were divided into 3 experimental groups, no capping (control; n = 15), capping with a 3-mm nerve conduit (n = 15), and capping with a 6-mm nerve conduit (n = 15). All rats were evaluated using an autotomy score and nerve stump histology 12 weeks after neurectomy. The nerve conduit was approximately 0.5 mm larger than the 1.5-mm diameter of the rat sciatic nerves to prevent nerve constriction.

RESULTS

The autotomy scores gradually exacerbated with time. Without capping, a typical bulbous neuroma was formed due to random axonal regeneration 2 weeks after neurectomy. Subsequently, the adhesion surrounding the neuroma expanded over time for 12 weeks, and at the 12-week time point, the highest average autotomy scores were observed in the no-capping (control) group, followed by the 3- and the 6-mm nerve conduit groups. Histologically, the distal axonal fibers became thinner and terminated within the 6-mm nerve conduit, whereas they were elongated and protruded across the 3-mm nerve conduit. Minimal perineural scar formation was present around the terminated axonal fibers in the 6-mm nerve conduit group. Expressions of anti-α smooth muscle actin and anti-sigma-1 receptor antibodies in the nerve stump significantly decreased in the 6-mm nerve conduit group.

CONCLUSIONS

In the rat sciatic nerve amputation model, nerve capping treatment with a bioabsorbable nerve conduit provided relief from neuroma-induced neuropathic pain and prevented perineural scar formation and neuroinflammation around the nerve stump. The appropriate nerve conduit length was determined to be more than 4 times the diameter of the original nerve.

Management of Painful Recurrent Intermetatarsal Neuroma Using Processed Porcine Extracellular Matrix Material: A Case Report

Painful recurrent stump neuroma presents a common clinical problem following the transection of a nerve after initial interdigital neuroma excision but there is no gold standard of treatment. A patient presented with pain symptoms consistent with recurrent intermetatarsal stump neuroma after undergoing previous surgery to excise a Hauser neuroma. The recurrent stump neuroma was excised and the resulting nerve was capped and implantation into intrinsic muscle. Postoperatively, the patient experienced a complete resolution of pain and return of normal function. This article discusses capping material characteristics and considers the factors that may contribute to clinical success.

Significance of alpha smooth muscle actin expression in traumatic painful neuromas: a pilot study in rats

Treatment of painful neuromas remains a challenge and the mechanism of neuroma-associated pain is not yet fully understood. In this study, we aimed to observe the expression of alpha smooth muscle actin (α-SMA) in traumatic neuromas and to investigate its possible roles in the cause of neuropathic pain in a rat model. The rat sciatic nerve was used and the experiment was divided into two parts. In part I, our results showed significantly higher levels of α-SMA and the pain marker c-fos in the autotomy group than in the no-autotomy group. In part II, the expression of α-SMA in neuromas was down- and up-regulated using SB-431542 and GW9662, respectively. A significant correlation between autotomy scores and the expression level of α-SMA was found (R = 0.957; p < 0.001) and the expression level of α-SMA was positively related to the autotomy scores (R² = 0.915, p < 0.001). We concluded that the expression of α-SMA plays certain roles in the neuroma-associated pain, either as a direct cause of pain or as an indirect marker of existence of local mechanical stimuli. Our findings may provide new insights into the development of new treatment modalities for the management of intractable painful neuromas.

The role of an aligned nanofiber conduit in the management of painful neuromas in rat sciatic nerves

BACKGROUND

Capping techniques have been used as a treatment modality for the prevention of neuroma formation and the management of neuropathic pain. However, the results are inconsistent and unpredictable. We hypothesize that this situation may be attributable, in part, to the disparities in the type of materials used to manufacturing of the conduits.

METHODS

In this study, a rat model was used and the sciatic nerve was selected for evaluation. In 1 capping group, a sciatic nerve stump was capped with a nonaligned nanofiber conduit (the nonaligned group), whereas in a second capping group, the conduit was made of aligned nanofibers (the aligned group). In another group, the sciatic nerve stump was not capped as a control (the control group). The results of autotomy behavior, extent of neuroma formation, histological changes in the neuroma, and the expression of c-fos as a pain marker in the fourth lumbar spinal cord were evaluated at 8 weeks postoperatively.

RESULTS

The control group presented more neuroma-like features in all the observed parameters in comparison with the 2 capping groups; of the 2 capping groups, the aligned group achieved even better outcomes than the nonaligned group.

CONCLUSIONS

Our findings indicate that the aligned nanofiber conduit is a promising biomaterial for the nerve capping technique, and new treatment strategies using aligned nanofiber conduits may be developed for the management of painful amputated neuromas.

Recurrent tarsal tunnel syndrome

Recurrence of tarsal tunnel syndrome after surgery may be due to inadequate release, lack of understanding or appreciation of the actual anatomy involved, variations in the anatomy of the nerve(s), failure to execute the release properly, bleeding with subsequent scarring, damage to the nerve and branches, persistent hypersensitivity of the nerves, and preexisting intrinsic damage to the nerve. Approaches include more thorough release, use of barrier materials to decrease adherence of the nerve to surrounding tissues to avoid traction neuritis, excisions of neuromas using conduits, and consideration of nerve stimulators and systemic medications to deal with persistent neural pain.

Mechanisms of nerve capping technique in prevention of painful neuroma formation

Nerve capping techniques have been introduced as a promising treatment modality for the treatment of painful neuroma with varied outcomes; however, its exact mechanism is still unknown. RhoA is one of the members of the RAS superfamily of GTPases that operate as molecular switches and plays an important role in peripheral nerve regeneration. Our aim was to investigate the structural and morphologic mechanisms by which the nerve capping technique prevents the formation of painful neuromas after neuroectomy. We also hoped to provide a theoretical basis for this treatment approach. An aligned nanofiber conduit was used for the capping procedure and the sciatic nerve of Sprague-Dawley rats was selected as the animal model. Behavioral analysis, extent of neuroma formation, histological assessment, expressions of pain markers of substance P and c-fos, molecular biological changes as well as ultrastructural features were investigated and compared with the findings in a no-capping control group. The formation of traumatic neuromas was significantly inhibited in the capping group with relatively “normal” structural and morphological features and no occurrence of autotomy and significantly lower expression of pain markers compared to the no-capping group. The gene expression of RhoA was consistently in a higher level in the capping group within 8 weeks after surgery. This study shows that capping technique will alter the regeneration state of transected nerves and reduce painful neuroma formation, indicating a promising approach for the treatment of painful neuroma. The initiation of the “regenerative brake” induced by structural as well as morphological improvements in the severed nerve is theorized to be most likely a key mechanism for the capping technique in the prevention of painful neuroma formation.