Repair of digital nerve defect with autogenous vein graft during flexor tendon surgery in zone 2

Treatment options for digital nerve injury: a systematic review and meta-analysis

BACKGROUND

Surgical treatment of finger nerve injury is common for hand trauma. However, there are various surgical options with different functional outcomes. The aims of this study are to compare the outcomes of various finger nerve surgeries and to identify factors associated with the postsurgical outcomes via a systematic review and meta-analysis.

METHODS

The literature related to digital nerve repairs were retrieved comprehensively by searching the online databases of PubMed from January 1, 1965, to August 31, 2021. Data extraction, assessment of bias risk and the quality evaluation were then performed. Meta-analysis was performed using the postoperative static 2-point discrimination (S2PD) value, moving 2-point discrimination (M2PD) value, and Semmes-Weinstein monofilament testing (SWMF) good rate, modified Highet classification of nerve recovery good rate. Statistical analysis was performed using the R (V.3.6.3) software. The random effects model was used for the analysis. A systematic review was also performed on the other influencing factors especially the type of injury and postoperative complications of digital nerve repair.

RESULTS

Sixty-six studies with 2446 cases were included in this study. The polyglycolic acid conduit group has the best S2PD value (6.71 mm), while the neurorrhaphy group has the best M2PD value (4.91 mm). End-to-side coaptation has the highest modified Highet's scoring (98%), and autologous nerve graft has the highest SWMF (91%). Age, the size of the gap, and the type of injury were factors that may affect recovery. The type of injury has an impact on the postoperative outcome of neurorrhaphy. Complications reported in the studies were mainly neuroma, cold sensitivity, paresthesia, postoperative infection, and pain.

CONCLUSION

Our study demonstrated that the results of surgical treatment of digital nerve injury are generally satisfactory; however, no nerve repair method has absolute advantages. When choosing a surgical approach to repair finger nerve injury, we must comprehensively consider various factors, especially the gap size of the nerve defect, and postoperative complications. Type of study/level of evidence Therapeutic IV.

Peripheral nerve regeneration in rats using nerve graft in a vein conduit pre-filled with platelet-rich fibrin (PRF)

Treatment of peripheral nerve injury is not always satisfactory. To improve results, specific adjuvant methods have been used, such as platelet-rich fibrin (PRF) and vein conduits. The goal of this study was to assess whether use of PRF and vein conduits after nerve suture improves nerve regeneration as measured by a functional score and histomorphometry analysis. Ten isogenic spontaneously hypertensive rats were randomly assigned to 4 experimental procedures: 1) Sham group (n = 10); 2) Nerve graft (NG) group (n = 10); 3) Nerve graft covered with a vein conduit (NGVC) (n = 10); and 4) Nerve graft covered with a vein conduit pre-filled with PRF (NGVCP) (n = 10). Nerve repair results were evaluated on: sciatic functional index (SFI) at 0, 30, 60 and 90 days; morphometric and morphologic analysis of the distal nerve; and histological analysis of Fluoro-Gold® stained motor neurons in the anterior horn of the spinal cord. Compared to the Sham control group, the NGVC and NGVCP groups exhibited lower SFI on all measures. The NGVC group showed improvement in SFI at day 90, which was significant compared to the NG group. Fiber and axon diameters were comparable in the NGVC and NGVCP groups, which were both significantly lower than in the Sham and NG groups. Significant improvement was expected with PRF, but in fact the release of factors from this substance was not as effective as hoped.

Muscle-in-Vein Conduits for the Treatment of Symptomatic Neuroma of Sensory Digital Nerves

Background: Considering the debilitating burden of neuroma resulting in a significant loss of function and excruciating pain, the use of muscle-in-vein conduits (MVCs) for the reconstruction of painful neuroma of sensory nerves of the fingers was assessed. Methods: We retrospectively analyzed 10 patients who underwent secondary digital nerve repair by MVCs. The recovery of sensibility was evaluated by static and moving two-point discrimination (2PDs, 2PDm) and Semmes-Weinstein monofilament testing (SWM). The minimum follow-up was set 12 months after the operation. Results: The median period between trauma and nerve repair was 13.4 weeks (IQR 53.5). After neuroma resection, defects ranged from 10–35 mm (mean 17.7 mm, SD 0.75). The successful recovery of sensibility was achieved in 90% of patients after a median follow-up of 27.0 months (IQR 31.00). The mean 2PDs and 2PDm was 8.1 mm (SD 3.52) and 5.2 mm (SD 2.27), respectively. Assessment by SWM resulted in a mean value of 3.54 (SD 0.69). Reduction in pain was achieved among all patients; eight patients reported the complete relief of neuropathic pain. There was no recurrence of neuroma in any patient. Conclusions: Muscle-in-vein conduits provide an effective treatment for painful neuroma of digital nerves, resulting in satisfactory restoration of sensory function and relief of pain.

Donors for nerve transplantation in craniofacial soft tissue injuries

Neural tissue is an important soft tissue; for instance, craniofacial nerves govern several aspects of human behavior, including the expression of speech, emotion transmission, sensation, and motor function. Therefore, nerve repair to promote functional recovery after craniofacial soft tissue injuries is indispensable. However, the repair and regeneration of craniofacial nerves are challenging due to their intricate anatomical and physiological characteristics. Currently, nerve transplantation is an irreplaceable treatment for segmental nerve defects. With the development of emerging technologies, transplantation donors have become more diverse. The present article reviews the traditional and emerging alternative materials aimed at advancing cutting-edge research on craniofacial nerve repair and facilitating the transition from the laboratory to the clinic. It also provides a reference for donor selection for nerve repair after clinical craniofacial soft tissue injuries. We found that autografts are still widely accepted as the first options for segmental nerve defects. However, allogeneic composite functional units have a strong advantage for nerve transplantation for nerve defects accompanied by several tissue damages or loss. As an alternative to autografts, decellularized tissue has attracted increasing attention because of its low immunogenicity. Nerve conduits have been developed from traditional autologous tissue to composite conduits based on various synthetic materials, with developments in tissue engineering technology. Nerve conduits have great potential to replace traditional donors because their structures are more consistent with the physiological microenvironment and show self-regulation performance with improvements in 3D technology. New materials, such as hydrogels and nanomaterials, have attracted increasing attention in the biomedical field. Their biocompatibility and stimuli-responsiveness have been gradually explored by researchers in the regeneration and regulation of neural networks.

Management and outcomes of flexor tendon repairs at a peripheral hospital: a New Zealand case series study

BACKGROUND

Current evidence for flexor tendon repair management and outcomes performed at peripheral centres is unclear. Most studies are based on evidence from specialist hand centres. This study evaluated a peripheral hospital in New Zealand; where all flexor tendon repairs were performed by a generalist Orthopaedic service. The purpose of the study was to benchmark management and outcomes from a peripheral hospital in comparison to international standards.

METHODS

A retrospective single-centre consecutive case series of Zones I and II flexor tendon repairs was extracted between 1 January 2014 and 1 January 2018. Medical records were used to evaluate management and outcomes of repairs. Hand therapy notes were used to evaluate rehabilitation protocols provided. The primary objective was to measure re-rupture and re-operation rates. Secondary objectives included auditing operative management and hand therapy compliance.

RESULTS

Forty-six patients (76 tendon repairs) were included in our final analysis. Mean follow up time to last clinical appointment was 11.8 weeks, and to last patient episode was 4.9 years. Most patients received timely surgery with a four-core repair using 3-0 or larger suture. All hand therapy followed a controlled active motion protocol. The re-operation rate was 19.6% (P = <0.05) and the re-rupture rate was 8.7% (P = 0.28).

CONCLUSIONS

Most flexor tendon injuries at this peripheral centre were managed according to international standards. However, high complication rates including re-operation and re-rupture occurred. Due to a lack of local comparison studies, confounding factors cannot be excluded as a contributor for these results.

Evidence-Based Approach to Timing of Nerve Surgery: A Review

ABSTRACT

Events causing acute stress to the health care system, such as the COVID-19 pandemic, place clinical decisions under increased scrutiny. The priority and timing of surgical procedures are critically evaluated under these conditions, yet the optimal timing of procedures is a key consideration in any clinical setting. There is currently no single article consolidating a large body of current evidence on timing of nerve surgery. MEDLINE and EMBASE databases were systematically reviewed for clinical data on nerve repair and reconstruction to define the current understanding of timing and other factors affecting outcomes. Special attention was given to sensory, mixed/motor, nerve compression syndromes, and nerve pain. The data presented in this review may assist surgeons in making sound, evidence-based clinical decisions regarding timing of nerve surgery.

Comparison of nerve conduits and nerve graft in digital nerve regeneration: A systematic review and meta-analysis

The goal of this systematic review and meta-analysis was to compare nerve conduits and nerve graft for peripheral nerve regeneration. This type of lesion frequently causes disability due to pain, paresthesia and motor deficit. On the PICO process, "P" corresponded to patients with peripheral digital nerve lesions of any age, gender or ethnicity, "I" to interventions with nerve conduits or nerve graft, "C" to the control group with no treatment, placebo or receiving other treatment, and "O" to outcome assessment of nerve regeneration. Initial search found in 3859 studies, including 2001 duplicates. The remaining 1858 studies were selected by title and/or abstract; 1798 articles were excluded, leaving 60 articles for full-text review. Thirty-nine of these 60 reports were excluded as not meeting our inclusion criteria, and 21 articles were ultimately included in the systematic review. For patients older than 40 years, there was a greater mean improvement on S2PD and M2PD tests with grafting, which seemed to be the better surgical technique, positively impacting prognosis. On the M2PD test, there was significantly greater improvement in 11-17.99 mm defects with grafting (P < 0.001); this finding should guide surgical strategy in peripheral nerve regeneration, to ensure better outcomes.

A novel tissue engineered nerve graft constructed with autologous vein and nerve microtissue repairs a long-segment sciatic nerve defect

Veins are easy to obtain, have low immunogenicity, and induce a relatively weak inflammatory response. Therefore, veins have the potential to be used as conduits for nerve regeneration. However, because of the presence of venous valves and the great elasticity of the venous wall, the vein is not conducive to nerve regeneration. In this study, a novel tissue engineered nerve graft was constructed by combining normal dissected nerve microtissue with an autologous vein graft for repairing 10-mm peripheral nerve defects in rats. Compared with rats given the vein graft alone, rats given the tissue engineered nerve graft had an improved sciatic static index, and a higher amplitude and shorter latency of compound muscle action potentials. Furthermore, rats implanted with the microtissue graft had a higher density and thickness of myelinated nerve fibers and reduced gastrocnemius muscle atrophy compared with rats implanted with the vein alone. However, the tissue engineered nerve graft had a lower ability to repair the defect than autogenous nerve transplantation. In summary, although the tissue engineered nerve graft constructed with autologous vein and nerve microtissue is not as effective as autologous nerve transplantation for repairing long-segment sciatic nerve defects, it may nonetheless have therapeutic potential for the clinical repair of long sciatic nerve defects. This study was approved by the Experimental Animal Ethics Committee of Chinese PLA General Hospital (approval No. 2016-x9-07) on September 7, 2016.

Immediate or Delayed Transplantation of a Vein Conduit Filled with Nasal Olfactory Stem Cells Improves Locomotion and Axogenesis in Rats after a Peroneal Nerve Loss of Substance

Over the recent years, several methods have been experienced to repair injured peripheral nerves. Among investigated strategies, the use of natural or synthetic conduits was validated for clinical application. In this study, we assessed the therapeutic potential of vein guides, transplanted immediately or two weeks after a peroneal nerve injury and filled with olfactory ecto-mesenchymal stem cells (OEMSC). Rats were randomly allocated to five groups. A3 mm peroneal nerve loss was bridged, acutely or chronically, with a 1 cm long femoral vein and with/without OEMSCs. These four groups were compared to unoperated rats (Control group). OEMSCs were purified from male olfactory mucosae and grafted into female hosts. Three months after surgery, nerve repair was analyzed by measuring locomotor function, mechanical muscle properties, muscle mass, axon number, and myelination. We observed that stem cells significantly (i) increased locomotor recovery, (ii) partially maintained the contractile phenotype of the target muscle, and (iii) augmented the number of growing axons. OEMSCs remained in the nerve and did not migrate in other organs. These results open the way for a phase I/IIa clinical trial based on the autologous engraftment of OEMSCs in patients with a nerve injury, especially those with neglected wounds.

Functional polymeric nerve guidance conduits and drug delivery strategies for peripheral nerve repair and regeneration

Peripheral nerve injuries can be extremely debilitating, resulting in sensory and motor loss-of-function. Endogenous repair is limited to non-severe injuries in which transection of nerves necessitates surgical intervention. Traditional treatment approaches include the use of biological grafts and alternative engineering approaches have made progress. The current article serves as a comprehensive, in-depth perspective on peripheral nerve regeneration, particularly nerve guidance conduits and drug delivery strategies. A detailed background of peripheral nerve injury and repair pathology, and an in-depth look into augmented nerve regeneration, nerve guidance conduits, and drug delivery strategies provide a state-of-the-art perspective on the field.

Bacterial cellulose tubes as a nerve conduit for repairing complete facial nerve transection in a rat model

PURPOSE

Functionality of the facial nerve is cosmetically important. While many techniques have been investigated, early and effective treatment for traumatic facial nerve paralysis remains challenging. Here, we aim to examine bacterial cellulose (BC) as a new tubularization material for improving facial nerve regeneration.

METHODS

Our study was performed on 40 female Sprague Dawley rats. Rats were randomly divided into four groups, with 10 rats per group. In all rats, the main trunk of the facial nerve was completely cut 8 mm before the branching point. For repairing the facial nerve, in group 1, the nerve was left to recover spontaneously (control group); in group 2, it was repaired by primary suturing (8.0 Ethilon sutures, Ethicon); in group 3, BC tubes alone were used to aid nerve repair; and in group 4, both BC tubes and primary sutures (8.0 Ethilon sutures) were used. After 10 weeks, the facial nerve regeneration was evaluated by the whisker movement test and electrophysiologically (nerve stimulation threshold and compound muscle action potential). Nerve regeneration was assessed by calculating the number of myelinated nerve fibers, and by microscopically evaluating the amount of regeneration and fibrosis.

RESULTS

No significant difference was observed among the groups in terms of whisker movement and electrophysiological parameters (P > 0.05). We found that the numbers of regenerating myelinated fibers were significantly increased (P < 0.05) when BC tubes were used as a nerve conduit.

CONCLUSIONS

BC can be easily shaped into a hollow tube that guides nerve axons, resulting in better nerve regeneration after transection.

Peripheral Nerve Regeneration: Current Status and New Strategies Using Polymeric Materials

Experiments concerning peripheral nerve regeneration have been reported since the end of the 19^th century. The need to implement an effective surgical procedure in terms of functional recovery has resulted in the appearance of several approaches to solve this problem. Nerve autograft was the first approach studied and is still considered the gold standard. Since autografts require donor harvesting, other strategies involving the use of natural materials have also been studied. Nevertheless, the results were not very encouraging and attention has moved towards the use of nerve conduits made from polymers, whose properties can be easily tailored and which allow the nerve conduit to be easily processed into a variety of shapes and forms. Some of these materials are already approved by the US Food and Drug Administration (FDA), as is presented here. Furthermore, polymers with conductive properties have very recently been subject to intensive study in this field, since it is believed that such properties have a positive influence in the regeneration of the new axons. This manuscript intends to give a global view of the mechanisms involved in peripheral nerve regeneration and the main strategies used to recover motor and sensorial function of injured nerves.

Peripheral nerve regeneration with conduits: use of vein tubes

Treatment of peripheral nerve injuries remains a challenge to modern medicine due to the complexity of the neurobiological nerve regenerating process. There is a greater challenge when the transected nerve ends are not amenable to primary end-to-end tensionless neurorraphy. When facing a segmental nerve defect, great effort has been made to develop an alternative to the autologous nerve graft in order to circumvent morbidity at donor site, such as neuroma formation, scarring and permanent loss of function. Tubolization techniques have been developed to bridge nerve gaps and have been extensively studied in numerous experimental and clinical trials. The use of a conduit intends to act as a vehicle for moderation and modulation of the cellular and molecular ambience for nerve regeneration. Among several conduits, vein tubes were validated for clinical application with improving outcomes over the years. This article aims to address the investigation and treatment of segmental nerve injury and draw the current panorama on the use of vein tubes as an autogenous nerve conduit.

Thoracic sympathetic nerve reconstruction for compensatory hyperhidrosis: the Melbourne technique

BACKGROUND

Compensatory hyperhidrosis (CH) is a potential complication following endoscopic thoracic sympathectomy (ETS) in the management of primary hyperhidrosis. CH is considered a permanent condition with significant psychosocial impacts but with few treatment options. Various reversal surgical techniques, aimed at reconstituting sympathetic pathways, have been developed but results have been inconsistent.

OBJECTIVE

We present two case reports of a novel technique of reversal surgery, the Melbourne technique, which was employed to treat severe CH that developed within 3-5 months following ETS. Both patients were followed-up to 8 years.

METHODS

The Melbourne technique employs an endoscopic approach to expose previously sympathectomized or sympathotomized thoracic sympathetic chains. In these two cases it was performed on the right side only. Instead of an interpositional nerve graft, an autogenous vein graft was simultaneously harvested and used as a nerve conduit to bridge the secondary nerve defect after neuroma excision. Long-term outcomes were assessed using the dermatology life quality index (DLQI) and the quality of life (QoL) questionnaires, which are validated for hyperhidrosis.

RESULTS

In both cases, patients reported postoperative improvements in QoL scores. However, the improvement was more marked in one case compared with the other. There were no significant immediate and long-term postoperative complications.

CONCLUSIONS

The Melbourne technique shows promise as an alternative to interpositional nerve grafts or nerve transfers employed in other endoscopic reversal surgeries for CH.

Evaluation of emergency nerve grafting for proper palmar digital nerve defects: a retrospective single centre study

HYPOTHESIS

Finger trauma often results in discontinuity of the proper palmar digital nerves. The goal of this study was to retrospectively evaluate the clinical outcomes of emergency nerve grafting and the resulting donor site morbidity.

MATERIAL AND METHOD

Three women and 13 men who had been operated between 2008 and 2012 were reviewed. The average patient age was 39 years (range 18-78). All were operated on an emergency basis. The average defect was 38 mm long (range 15-60). The nerves were harvested from four sites: lateral antebrachial cutaneous nerve (12 cases), banked finger (2 cases), terminal portion of posterior interosseous nerve (1 case) and anterior interosseous nerve (1 case). The evaluation consisted of patient questioning and clinical examination of the treated finger and donor site. An objective sensory exam was also performed. The results were expressed according to the British Medical Research Council (MRC) classification.

RESULTS

There was little donor site morbidity (2 cases of symptomatic hypoesthesia, 1 case of scar hypersensitivity). Sixty-nine percent of patients stated that their grafted finger did not cause them any trouble during activities of daily living. Three patients required job retraining. Pain in the grafted finger was 0.6 (range 0-5) on the VAS. Normal sensation was restored in 31% of cases based on the monofilament sensory test; 25% had a slight decrease in touch sensitivity and 25% had reduced protective sensations. Weber's two-point discrimination test found 50% normal sensibility (threshold<6mm) and 6% with mediocre sensibility (threshold of 6-10mm). On the MRC grading scale, 50% of patients were at S4, 6% at S3+, 19% at S3, 12% at S2 and 12% at S1.

CONCLUSION

There were 56% good results in this patient series (S3+/S4) and no patients at S0. Donor site morbidity was rare. Thus use of nerve grafting is still a relevant option in an emergency setting.

LEVEL OF EVIDENCE

Level IV.

An inside-out vein graft filled with platelet-rich plasma for repair of a short sciatic nerve defect in rats

Platelet-rich plasma containing various growth factors can promote nerve regeneration. An inside-out vein graft can substitute nerve autograft to repair short nerve defects. It is hypothesized that an inside-out vein graft filled with platelet-rich plasma shows better effects in the repair of short sciatic nerve defects. In this study, an inside-out vein autograft filled with platelet-rich plasma was used to bridge a 10 mm-long sciatic nerve defect in rats. The sciatic nerve function of rats with an inside-out vein autograft filled with platelet-rich plasma was better improved than that of rats with a simple inside-out vein autograft. At 6 and 8 weeks, the sciatic nerve function of rats with an inside-out vein autograft filled with platelet-rich plasma was better than that of rats undergoing nerve autografting. Compared with the sciatic nerve repaired with a simple inside-out vein autograft, the number of myelinated axons was higher, axon diameter and myelin sheath were greater in the sciatic nerve repaired with an inside-out vein autograft filled with platelet-rich plasma and they were similar to those in the sciatic nerve repaired with nerve autograft. These findings suggest that an inside-out vein graft filled with platelet-rich plasma can substitute nerve autograft to repair short sciatic nerve defects.

The management of digital nerve injuries

A tension-free coaptation is a key factor for the successful outcome of any nerve repair. A variety of host factors influence the outcome of digital nerve repair more than the type of repair per se. Although autologous graft remains the reference standard for reconstruction of any critical digital nerve defect, allografts and conduits have assumed an increasing role.

Sensory reinnervation of muscle spindles after repair of tibial nerve defects using autogenous vein grafts

Motor reinnervation after repair of tibial nerve defects using autologous vein grafts in rats has previously been reported, but sensory reinnervation after the same repair has not been fully investigated. In this study, partial sensory reinnervation of muscle spindles was observed after repair of 10-mm left tibial nerve defects using autologous vein grafts with end-to-end anastomosis in rats, and functional recovery was confirmed by electrophysiological studies. There were no significant differences in the number, size, or electrophysiological function of reinnervated muscle spindles between the two experimental groups. These findings suggest that repair of short nerve defects with autologous vein grafts provides comparable results to immediate end-to-end anastomosis in terms of sensory reinnervation of muscle spindles.

Biofabrication and testing of a fully cellular nerve graft

Rupture of a nerve is a debilitating injury with devastating consequences for the individual's quality of life. The gold standard of repair is the use of an autologous graft to bridge the severed nerve ends. Such repair however involves risks due to secondary surgery at the donor site and may result in morbidity and infection. Thus the clinical approach to repair often involves non-cellular solutions, grafts composed of synthetic or natural materials. Here we report on a novel approach to biofabricate fully biological grafts composed exclusively of cells and cell secreted material. To reproducibly and reliably build such grafts of composite geometry we use bioprinting. We test our grafts in a rat sciatic nerve injury model for both motor and sensory function. In particular we compare the regenerative capacity of the biofabricated grafts with that of autologous grafts and grafts made of hollow collagen tubes by measuring the compound action potential (for motor function) and the change in mean arterial blood pressure as consequence of electrically eliciting the somatic pressor reflex. Our results provide evidence that bioprinting is a promising approach to nerve graft fabrication and as a consequence to nerve regeneration.

Advances in experimental and clinical studies of chemotaxis

The theory of chemotaxis has been widely accepted, but its mechanisms are disputed. Chemotactic growth of peripheral nerves may be tissue, topographic and end-organ specific. Recent studies indicated that peripheral nerve regeneration lacks topographic specificity, but whether it has end-organ specificity is disputed. Chemotaxis in nerve regeneration is affected by the distance between stumps, volume, and neurotrophic support, as well as the structure of distal nerve stumps. It can be applied to achieve precise repair of nerves and complete recovery of end organ function. Small gap sleeve bridging technique, which is based on this theory shows promising effects but it is still challenging to find the perfect combination of nerve conduits, cells and neurotrophic factors to put it intoits best use. In this paper, we made a comprehensive review of mechanisms, effect factors and applications of chemotaxis.

Peroneal nerve reconstruction by using glycerol-preserved veins: histological and functional assessment in rats

PURPOSE

To compare the degree of neural regeneration in rats upon interposition of autologous nerve graft, autogenous vein, glycerol-preserved autogenous vein, and glycerol-preserved allogeneic vein using qualitative and quantitative histological analyses as well as functional assessments.

METHODS

Peroneal nerves were reconstructed differently in four groups of animals. Functional assessments were performed pre- and postoperatively for a period of six weeks. After six weeks, the animals were sacrificed and histological evaluations were performed.

RESULTS

Histological patterns of autogenous veins without preservation showed pronounced neoangiogenesis and extensive axonal rarefaction, as confirmed by axonal counting and functional assessments. Glycerol-preserved veins had results similar to the control.

CONCLUSIONS

Glycerol-preserved autogenous or allogeneic veins showed similar results to autograft results. The autogenous vein (without preservation in glycerol) presented histological and functional outcomes statistically lower than other groups.

Neural-differentiated mesenchymal stem cells incorporated into muscle stuffed vein scaffold forms a stable living nerve conduit

Autologous nerve grafts to bridge nerve gaps have donor site morbidity and possible neuroma formation resulting in development of various methods of bridging nerve gaps without using autologous nerve grafts. We have fabricated an acellular muscle stuffed vein seeded with differentiated mesenchymal stem cells (MSCs) as a substitute for nerve autografts. Human vein and muscle were both decellularized by liquid nitrogen immersion with subsequent hydrolysis in hydrochloric acid. Human MSCs were subjected to a series of treatments with a reducing agent, retinoic acid, and a combination of trophic factors. The differentiated MSCs were seeded on the surface of acellular muscle tissue and then stuffed into the vein. Our study showed that 35-75% of the cells expressed neural markers such as S100b, glial fibrillary acidic protein (GFAP), p75 NGF receptor, and Nestin after differentiation. Histological and ultra structural analyses of muscle stuffed veins showed attachment of cells onto the surface of the acellular muscle and penetration of the cells into the hydrolyzed fraction of muscle fibers. We implanted these muscle stuffed veins into athymic mice and at 8 weeks post-implantation, the acellular muscle tissue had fully degraded and replaced with new matrix produced by the seeded cells. The vein was still intact and no inflammatory reactions were observed proving the biocompatibility and biodegradability of the conduit. In conclusion, we have successfully formed a stable living nerve conduit which may serve as a substitute for autologous nerves.

Digital nerve injuries: a review of predictors of sensory recovery after microsurgical digital nerve repair

BACKGROUND

Optimal surgical management of digital nerve lesions remains uncertain despite the publication of numerous studies. The purposes of this review were primarily to analyze whether there is a superior surgical technique for digital nerve repair and secondarily to statistically verify the variables to be predictors of sensory recovery.

METHODS

A literature search was performed using PubMed including citation from MEDLINE. Studies were included if they involved patients with digital nerve lacerations in whom end-to-end neurorrhaphy, nerve grafts, conduits, or end-to-side neurorrhaphy were performed. Further, the sensory outcome had to be assessed according to the modified American Society for Surgery of the Hand guidelines to stratify for two-point discrimination in millimeters. The variables age, follow-up, delay in repair, type of trauma, and gap length were extracted. The association between each predictor and response was assessed using a linear mixed model and corrected for heterogeneity between studies. Significance was considered present at p ≤ 0.05.

RESULTS

Of the 34 articles found, 14 articles were included giving appropriate individual data for 191 nerves. There was no statistically significant difference in outcome between operation techniques. Age and follow-up were verified predictors of sensory recovery.

CONCLUSION

In this review, the type of operation for digital nerve repair does not influence sensory outcome. However, we verified outcome to be influenced by the patient's age and the follow-up period. To add more scientific evidence to our results, larger cohort prospective studies need to be done with better detailed description of data.

Experience of using the bioresorbable copolyester poly(DL-lactide-ε-caprolactone) nerve conduit guide Neurolac™ for nerve repair in peripheral nerve defects: report on a series of 28 lesions

Synthetic nerve guides are occasionally used to repair nerve defects. The aim of the present work was to analyse the results of Neurolac™ use in a series of 23 patients. We operated on 28 nerve lesions located on various sites: arm (n = 1), elbow (n = 5), forearm (n = 4), wrist (n = 2), palm (n = 5), fingers (n = 11). Defects averaged 11.03 mm and were repaired using Neurolac™. After an average of 21.9 months' follow up (3-45 months), subjective criteria (pain, cold intolerance, Quick DASH) and objective criteria (strength, Weber and Semmes-Weinstein sensitivity tests) were compared with the contralateral side. Average pain score was 2.17/10. Cold intolerance was reported in fifteen cases. Quick DASH averaged 35.37/100. Grip strength averaged 64.62% of the contralateral side. As regards sensitivity, the difference between the two sides was 18.89 on Weber's test, and 46.92 on Semmes-Weinstein. Defect size did not affect the outcomes. We observed eight complications the most serious being two fistulizations of the Neurolac™ device close to a joint and one neuroma. Neurolac™ presents some advantages (resorption, semi-permeability, emergency use, tenseless repair) like other synthetic guides used for nerve regeneration and its transparency constitutes an added benefit. However, some difficulty in its handling and its expensiveness represent real disadvantages. Our results are not in favour of its use in repairing hand nerve defects.

Toward engineering functional organ modules by additive manufacturing

Tissue engineering is emerging as a possible alternative to methods aimed at alleviating the growing demand for replacement tissues and organs. A major pillar of most tissue engineering approaches is the scaffold, a biocompatible network of synthetic or natural polymers, which serves as an extracellular matrix mimic for cells. When the scaffold is seeded with cells it is supposed to provide the appropriate biomechanical and biochemical conditions for cell proliferation and eventual tissue formation. Numerous approaches have been used to fabricate scaffolds with ever-growing complexity. Recently, novel approaches have been pursued that do not rely on artificial scaffolds. The most promising ones utilize matrices of decellularized organs or methods based on multicellular self-assembly, such as sheet-based and bioprinting-based technologies. We briefly overview some of the scaffold-free approaches and detail one that employs biological self-assembly and bioprinting. We describe the technology and its specific applications to engineer vascular and nerve grafts.

Autogenous grafts/allografts/conduits for bridging peripheral trigeminal nerve gaps

Nerve repairs and grafting techniques have been around for many years. Autogenous nerve grafts have worked reasonably well in the right circumstances but are associated with difficulties in achieving a proper donor-host match and with postsurgical sequelae at the donor site. Vein grafts seem to work almost as well as autogenous nerve grafts in digital nerve repairs that require a graft less than 3 cm in length. Currently, the most promising nerve graft materials are the polyglycolic acid tubes and processed decellularized allografts, which have shown good results without the morbidity of autogenous nerve grafts. However, more research studies using these materials for TN repairs are essential to validate the superiority of these procedures.

A prospective randomized study comparing woven polyglycolic acid and autogenous vein conduits for reconstruction of digital nerve gaps

PURPOSE

The optimal management of a nerve gap within the fingers remains an unanswered question in hand surgery. The purpose of this study was to compare the sensory recovery, cost, and complication profile of digital nerve repair using autogenous vein and polyglycolic acid conduits.

METHODS

We enrolled patients undergoing repair of digital nerve injuries with gaps precluding primary repair. The minimum gap that was found to preclude primary repair was 4 mm. Each nerve repair was randomized to the type of nerve repair with either a woven polyglycolic acid conduit or autogenous vein. Time required for repair was recorded. We performed sensory testing, consisting of static and moving 2-point discrimination, at 6 and 12 months after repair. We compared patient factors between the 2 groups using chi-square and Student's t-test. We compared sensory recovery between the 2 groups at each time point using Student's t-test and compared time and cost of repair.

RESULTS

We enrolled 42 patients with 76 nerve repairs. Of these, 37 patients (representing 68 repairs) underwent sensory evaluation at the 6-month time point. The median age in this group was 35 years. We repaired 36 nerves with synthetic conduit and 32 with vein. Nerve gaps ranged from 4 to 25 mm (mean, 10 mm). Study groups were not significantly different regarding age, time to repair, gap length, medical history, smoking history, or worker's compensation status. Time to harvest the vein was longer but the average cost of materials and surgery in the vein group was $1,220, compared with $1,269 for synthetic conduit repairs. These differences were not statistically significant. Mean static and moving 2-point discrimination at 6 months for the synthetic conduit group were 8.3 ± 2.0 and 6.6 ± 2.3, respectively, compared with 8.5 ± 1.8 and 7.1 ± 2.2 for the vein group. Values at 12 months for the synthetic conduit group were 7.5 ± 1.9 and 5.6 ± 2.2, compared with 7.6 ± 2.6 and 6.6 ± 2.9 for the vein group. These differences were not statistically significant. Smokers and worker's compensation patients had a worse sensory recovery at 12 months postrepair. There were 2 extrusions in the synthetic conduit group requiring reoperation; however, the difference in extrusion rate was not found to be statistically significant.

CONCLUSIONS

Sensory recovery after digital nerve reconstruction with autogenous vein conduit was equivalent to that using polyglycolic acid conduit, with a similar cost profile and fewer postoperative complications.

Clinical application of inside-out vein grafts for the treatment of sensory nerve segmental defect

PURPOSE

The gold standard for the treatment of segmental nerve defect is an autogenous nerve graft. However, donor site morbidity is an inevitable complication. We substituted an autogenous nerve graft with an inside-out vein graft for the treatment of segmental sensory nerve defect and the clinical results were evaluated retrospectively.

PATIENTS AND METHODS

Eleven patients of sensory nerve defects have undertaken inside-out vein grafts for the recovery of sensation. The involved nerves were digital nerves in three cases, peroneal nerves in two cases, saphenous nerve in two cases, and superficial radial nerves in four cases. The average length of defects was 2.71 cm (1-6 cm). Donor veins were harvested 4 mm longer than nerve defects and everted to promote nerve regeneration. Patients' objective satisfactions and two-point discriminations were determined, the Semmes-Weinstein monofilament test was performed, and British Medical Council sensory functional scores were evaluated.

RESULTS

Sensory functional scores recovered to over S3 in all cases. No donor site morbidity was caused by vein harvesting, and all patients achieved satisfactory results with protective sensation at involved sites.

CONCLUSION

The inside-out vein graft offers a good surgical alternative to an autogenous nerve graft for the reconstruction of sensory nerve defects without donor site morbidity.

[Retrospective monocentric comparative evaluation by sifting of vein grafts versus nerve grafts in palmar digital nerves defects. Report of 32 cases]

AIM

Palmar digital nerves defects can be treated by conventional nerve grafts or by means of a conduit, such as a vein. We compared a vein graft technique to a nerve graft technique in a retrospective monocentric study.

MATERIAL AND METHOD

A surgeon who was not involved in the treatment reviewed blind 15 nerve grafts and 17 vein grafts. The evaluation concerned sensitivity, pain, donor site morbidity, social integration and autoassessment of the benefits by the patient. Data were compacted by a sifting method eliminating bad results. The classical functional scores (British Medical Research Council, Möberg, Chanson, Alnot, Dumontier) were also used.

RESULTS

The evaluation was carried out at least 11 months after treatment. Defect was never greater than 30 mm. After sifting, vein grafts appeared less efficient than nerve grafts (41% good results against 73%), except in emergencies (86% good results).

CONCLUSION

For defect loss of no more than 30 mm in emergencies, the authors propose to use vein grafting. In other situations, the surgeon must take into account the patient's profile and the hemi-pulp concerned, dominant or non-dominant, before opting for a nerve or a vein graft.

Primary transposition of digital nerves into muscle in second ray amputation: a possible answer for neuroma formation

After second ray amputation, neuroma formation is a common cause of postoperative pain localized at the web space due to sectioning and leaving the digital nerve ends. Most of the time the complaints lead to two or more operations, using several described techniques, with some limited success. However, transposition of the digital nerve ends into interosseous muscles should be added to the second ray amputation as a part of procedure, neuroma problems can be solved. The technique is described by detail in this article which is advised for other ray amputations and during revisions.

Secondary nerve reconstruction using vein conduit grafts for neglected digital nerve injuries

Digital nerve defects can result from neglected nerve injuries. The standard method of reconstruction is nerve grafting, but donor-site morbidity encourages searching for alternative graft materials, including vein conduit grafts. From 1995-2005, three patients with neglected digital nerve injuries received vein conduit grafting for digital nerve reconstruction in our hospital. The interval between the injury and the reconstructive procedure ranged from 17 days to 2 years, and the length of the defects ranged from 0.8 to 2.5 cm. All the vein grafts were harvested from the distal forearm. Patient 1 had a moving and a static two-point discrimination (M2PD and S2PD) of 3 and 4 mm, respectively, at a 12-year follow-up. Patient 2 had an M2PD of 5 mm and S2PD of 6 mm at an 11-year follow-up, and the patient 3 had both an M2PD and S2PD of 4 mm at a near 3-year follow-up. They all achieved useful sensory function (S3 and S3+) by modified Highet and Sander criteria. Although previous studies showed secondary repair using vein grafts yielded worse sensory recovery than that of primary repair, in our cases, secondary digital nerve reconstruction with vein conduit grafts gives excellent results at the long-term sensory evaluation, two of them with more than 10 years' follow-up. To the best of our knowledge, this might be the longest follow-up after secondary digital nerve reconstruction using a vein conduit graft. It bears the advantages of readily accessible, no donor-site morbidity, and compatible in size with digital nerves.

La réparation de pertes de substance des nerves digitaux avec la technique de la greffe veineuse plus interposition de tissu nerveux. Étude prospective et randomisée

OBJECTIVE

This study aims to compare the results of treating digital nerve defects with autologous sural nerve grafts as compared to using a vein conduit with interposition of a posterior interosseous nerve segment.

METHODS

This study is a clinical, prospective, randomized and blinded trial, comparing digital nerve defects treated by two different surgical techniques. It included a total of 50 digital nerves (25 patients in each treatment group), with a mean follow up of 10.2 (SD 1.4) months. In addition, the impact of five different factors (type of surgery, size of nerve defect, patient's age, type of lesion and lesion age) on the final outcome were evaluated.

RESULTS

In respect of the sensory assessment, the static two point discrimination score was 6 mm for both groups . According to the Al-Ghazal Scoring Method, the autolougus sural nerve graft group scored a mean (sd) of 7.7 (1.9) points, while vein conduit with interposition of a posterior interosseous nerve segment group scored 6.9 (2.1). Under multivariate analysis, both patient's age and lesion age proved to be important independent factors, having influenced almost all results. The group treated with vein conduit with interposition of a posterior interosseous nerve segments showed fewer complications than the group treated using sural nerve.

CONCLUSION

Based on the results obtained, we concluded that the sensory scores were equal in both groups. We also concluded that the vein conduit and posterior interosseous nerve graft procedure offered some advantages in terms of the complication rate.

Nerve conduits

The evolution of peripheral nerve repair is reviewed with respect to the development of the nerve conduit. The rationale and available scientific evidence to support the use of nerve conduits is presented. Therapy evaluation and treatment protocols for patients with peripheral nerve repairs with nerve conduits are detailed. The authors present clinical experience to date with 73 cases of peripheral nerves repaired with the NeuraGenR collagen nerve conduit.

Autologous fibrin glue in peripheral nerve regeneration in vivo

The activity of several growth factors on peripheral nerve regeneration is reported. Autologous fibrin glue contains a large number of platelets, which release significant quantities of growth factors. In order to understand the role of autologous fibrin glue in peripheral nerve regeneration, a 15-mm rabbit peroneal nerve defect was repaired using a vein graft filled with autologous fibrin glue. Axonal regeneration was examined using histological and electrophysiological methods. The extent of axonal regeneration was superior when treated with autologous fibrin glue. Our data suggest that fibrin nets formed by fibrinogen, in combination with growth factors present in autologous fibrin glue, might effectively promote peripheral nerve regeneration in nerve defects.

Enhanced peripheral nerve regeneration through a poled bioresorbable poly(lactic-co-glycolic acid) guidance channel

In this study we investigated the effects of materials prepared with electrical poling on neurite outgrowth in vitro and nerve regeneration in vivo. Neuro-2a cells were seeded on poled and unpoled poly(lactic-co-glycolic) (PLGA) films and observed at time periods 24, 48 and 72 h post-seeding. The percentage of cells with neurites and the neurites per cell were quantified using light microscopy. At 48 and 72 h post-seeding, both the number of cells with neurites and the neurites per cell were significantly increased on the poled films compared to those on unpoled films. An established rat sciatic nerve model was used for in vivo studies to assess the effects of PLGA guides, poled for two different periods, on peripheral nerve regeneration. Guides were inserted in rats to bridge a 1.0 cm gap created in the right sciatic nerve. After four weeks, nerves regenerated through poled guides displayed a significant increase in conduction velocity and significantly increased numbers of axons across the guides, as compared to nerves regenerating through an unpoled guidance channel. Electrical poling was shown to promote neurite growth, axon regeneration and the conduction rate of the repaired nerve. We concluded that guides prepared with electrical poling enhance peripheral nerve regeneration.