Arterialized Posterior Interosseous Nerve Graft for Digital Neuroma

Vascular supply of the radial nerve and its terminal branches: an anatomical study

PURPOSE

The aim of this cadaveric study was to further describe the vascular supply of the radial, posterior interosseous and superficial radial nerves.

METHODS

11 cadaveric upper limbs, injected with colored latex, were dissected. Vascular afferents to the radial nerve, superficial radial nerve (SRN) and posterior interosseous nerve (PIN) were described and located. Their origin was identified and its distance to interepicondylar line was measured.

RESULTS

The radial nerve had an average of 3 vascular afferents (1-5), of septomuscular origin in 54% of cases. 46% came from adjacent arteries. The PIN had an average of 8 vascular afferents (6-14), arising from septomuscular branches in 82% of cases. The PIN was vascularized in 100% of cases by a large arterial plexus originating from the supinator muscle between its two heads. The SRN had an average of 4 vascular afferents (3-7). Before crossing the septum of the brachioradialis, vascularization was predominantly septomuscular; after crossing the septum, the nerve was exclusively vascularized by septocutaneous arteries.

CONCLUSION

This is the first study to describe the vascularization of the radial nerve and its terminal branches along their entire length. Our results are in line with the data available in the literature. An arterial plexus between the two heads of the supinator was surrounding the PIN in all cases. This vascular plexus might be involved in dynamic compression of the posterior interosseous nerve.

The Role of Vascularized Nerve Grafting in Upper Extremity Reconstruction: A Systematic Review

Purpose

Vascularized nerve grafts (VNGs) have been proposed as encouraging alternatives to conventional nerve grafting; however, there is ongoing debate regarding the clinical advantages of the approach compared with standard grafting. This review aims to gather and analyze reported cases of upper extremity nerve repair using VNGs documented in the published literature.

Methods

In accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, PubMed/MEDLINE, Embase, and Cochrane were searched. Inclusion criteria for this review included the following: (1) human subjects or cadaveric studies, (2) describing a vascularized nerve grafting procedure or suggesting a nerve and vascular supply for a potential vascularized nerve graft, and (3) upper extremity nerve repair in clinical studies.

Results

Data were extracted from 45 clinical studies. Of 535 patients, the most common injury pattern was root avulsion and rupture (88.7%). The most utilized VNG was the ulnar nerve (72.8%), followed by nerve to long head of triceps (8.8%) and sural nerve (8.2%); most common recipients were median (57.6%), axillary (12.5%), and musculocutaneous nerves (11.9%). Between patients who had medical research council scale scores, 69% had functional (M3 and above) motor and 72.7% sensory (S3<) recovery.

Conclusions

Vascularized nerve grafts can increase the odds of functional gain in challenging conditions such as large nerve gaps, nerve avulsions, ruptures, and scarred and irradiated beds. With the exception of well-known VNG options, literature on alternative VNGs is largely confined to case reports and series, with additional published cases, outcomes, and basic science research needed to establish the role of VNGs in nerve repair.

Clinical relevance

Our findings support the promise of VNGs for complex cases of nerve reconstruction. Evidence from published cases also indicates that VNGs enhance motor and sensory function recovery compared with traditional nerve grafting.

Vascularized posterior interosseous nerve graft for digital neurovascular bundle reconstruction

INTRODUCTION

Despite the progress in microsurgery in recent decades, neurovascular bundle defects during ring finger injuries still pose challenges for the surgeon. Usually, a reversed venous graft and a non-vascularized nerve graft are utilized to reconstruct this defect. One of the most common challenges encountered when using a venous graft is the caliber mismatch between the graft and the digital arterial ends. The use of an arterialized nerve graft (neurovascular graft) is poorly described and could represent an attractive reconstructive option.

CASE PRESENTATION

We present the case of a 36-year-old manual worker, a non-smoker, with no significant medical or surgical comorbidities, who presented a ring avulsion type trauma, leading to the amputation of the third left finger at the distal interphalangeal joint and avulsion of the circumferential skin at the level of the middle and proximal phalanges (Urbaniak III). The patient presented a neurovascular bundle defect of 3 cm, reconstructed by the vascularized posterior interosseous nerve graft along the distal perforator of the dorsal branch of the anterior interosseous artery serving both as an interpositional arterial conduit and as a nerve graft. The results of postoperative nerve regeneration at three years are satisfactory, with the patient demonstrating a two-point discrimination measured at 6 mm.

CONCLUSION

Simultaneous digital artery and nerve reconstruction using a neurovascular flap is very appealing to the hand surgeon as it offers several advantages over traditional methods, particularly the ideal diameter match between the digital arteries and the distal perforator of the dorsal branch of the anterior interosseous artery.

Flow-Through Arterialized Posterior Interosseous Nerve Grafts for Digital Neurovascular Bundle Defects: Anatomical Study

BACKGROUND

Digital neurovascular bundle defects are often encountered during crush or avulsion injuries and require complex reconstruction. Use of an arterialized nerve graft (neurovascular graft) serving both as an interpositional arterial conduit and as a nerve graft could be a reconstructive option in these cases. In this anatomical study, the authors aimed to describe a neurovascular graft of the posterior interosseous nerve and a branch of the anterior interosseous artery for neurovascular bundle reconstruction of the fingers.

METHODS

Eighteen forearms were injected with red latex in order to collect the anatomical characteristics of the posterior interosseous nerve and the artery running near it.

RESULTS

In all cases, the posterior interosseous nerve was followed by a branch of the anterior interosseous artery: the distal dorsal branch of the anterior interosseous nerve. The origin of this artery was proximal to the radiocarpal joint, at an average of 56.5 ± 11.1 mm. The proximal and distal diameters of the branch of the anterior interosseous artery were 1.6 ± 0.2 and 1.1 ± 0.2 mm, respectively. The proximal and distal diameters of the posterior interosseous nerve were 1.2 ± 0.3 mm and 1.1 ± 0.3 mm, respectively.

CONCLUSIONS

These results show that a potential free neurovascular graft using the posterior interosseous nerve as nerve graft and the anterior interosseous artery as an arterial bypass to reconstruct both the nerve and arterial tree of the finger could be a useful approach. The authors speculate that this graft could be used to reconstruct the neurovascular bundle of amputated or devascularized digits.

Microcomputed analysis of nerve angioarchitecture after combined stem cell delivery and surgical angiogenesis to nerve allograft

INTRODUCTION

A detailed three-dimensional (3D) evaluation of microvasculature is evolving to be a powerful tool, providing mechanistic understanding of angiomodulating strategies. The aim of this study was to evaluate the microvascular architecture of nerve allografts after combined stem cell delivery and surgical angiogenesis in a rat sciatic nerve defect model.

MATERIALS AND METHODS

In 25 Lewis rats, sciatic nerve gaps were repaired with (i) autografts, (ii) allografts, (iii) allografts wrapped in a pedicled superficial inferior epigastric artery fascia (SIEF) flap to provide surgical angiogenesis, combined with (iv) undifferentiated mesenchymal stem cells (MSC) and (v) MSCs differentiated into Schwann cell-like cells. At two weeks, vascular volume was measured using microcomputed tomography, and percentage and volume of vessels at different diameters were evaluated and compared with controls.

RESULTS

The vascular volume was significantly greatest in allografts treated with undifferentiated MSCs and surgical angiogenesis combined as compared to all experimental groups (P<0.01 as compared to autografts, P<0.0001 to allografts, and P<0.05 to SIEF and SIEF combined with differentiated MSCs, respectively). Volume and diameters of vessel segments in nerve allografts were enhanced by surgical angiogenesis. These distributions were further improved when surgical angiogenesis was combined with stem cells, with greatest increase found when combined with undifferentiated MSCs.

CONCLUSIONS

The interaction between vascularity and stem cells remains complex, however, this study provides some insight into its synergistic mechanisms. The combination of surgical angiogenesis with undifferentiated MSCs specifically, results in the greatest increase in revascularization, size of vessels, and stimulation of vessels to reach the middle longitudinal third of the nerve allograft.

The role of vascularization in nerve regeneration of nerve graft

Vascularization is an important factor in nerve graft survival and function. The specific molecular regulations and patterns of angiogenesis following peripheral nerve injury are in a broad complex of pathways. This review aims to summarize current knowledge on the role of vascularization in nerve regeneration, including the key regulation molecules, and mechanisms and patterns of revascularization after nerve injury. Angiogenesis, the maturation of pre-existing vessels into new areas, is stimulated through angiogenic factors such as vascular endothelial growth factor and precedes the repair of damaged nerves. Vascular endothelial growth factor administration to nerves has demonstrated to increase revascularization after injury in basic science research. In the clinical setting, vascularized nerve grafts could be used in the reconstruction of large segmental peripheral nerve injuries. Vascularized nerve grafts are postulated to accelerate revascularization and enhance nerve regeneration by providing an optimal nutritional environment, especially in scarred beds, and decrease fibroblast infiltration. This could improve functional recovery after nerve grafting, however, conclusive evidence of the superiority of vascularized nerve grafts is lacking in human studies. A well-designed randomized controlled trial comparing vascularized nerve grafts to non-vascularized nerve grafts involving patients with similar injuries, nerve graft repair and follow-up times is necessary to demonstrate the efficacy of vascularized nerve grafts. Due to technical challenges, composite transfer of a nerve graft along with its adipose tissue has been proposed to provide a healthy tissue bed. Basic science research has shown that a vascularized fascial flap containing adipose tissue and a vascular bundle improves revascularization through excreted angiogenic factors, provided by the stem cells in the adipose tissue as well as by the blood supply and environmental support. While it was previously believed that revascularization occurred from both nerve ends, recent studies propose that revascularization occurs primarily from the proximal nerve coaptation. Fascial flaps or vascularized nerve grafts have limited applicability and future directions could lead towards off-the-shelf alternatives to autografting, such as biodegradable nerve scaffolds which include capillary-like networks to enable vascularization and avoid graft necrosis and ischemia.