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

Peripheral nerve reconstruction after injury: a review of clinical and experimental therapies

Unlike other tissues in the body, peripheral nerve regeneration is slow and usually incomplete. Less than half of patients who undergo nerve repair after injury regain good to excellent motor or sensory function and current surgical techniques are similar to those described by Sunderland more than 60 years ago. Our increasing knowledge about nerve physiology and regeneration far outweighs our surgical abilities to reconstruct damaged nerves and successfully regenerate motor and sensory function. It is technically possible to reconstruct nerves at the fascicular level but not at the level of individual axons. Recent surgical options including nerve transfers demonstrate promise in improving outcomes for proximal nerve injuries and experimental molecular and bioengineering strategies are being developed to overcome biological roadblocks limiting patient recovery.

Peripheral nerve reconstruction after injury: a review of clinical and experimental therapies

Unlike other tissues in the body, peripheral nerve regeneration is slow and usually incomplete. Less than half of patients who undergo nerve repair after injury regain good to excellent motor or sensory function and current surgical techniques are similar to those described by Sunderland more than 60 years ago. Our increasing knowledge about nerve physiology and regeneration far outweighs our surgical abilities to reconstruct damaged nerves and successfully regenerate motor and sensory function. It is technically possible to reconstruct nerves at the fascicular level but not at the level of individual axons. Recent surgical options including nerve transfers demonstrate promise in improving outcomes for proximal nerve injuries and experimental molecular and bioengineering strategies are being developed to overcome biological roadblocks limiting patient recovery.

Overcoming short gaps in peripheral nerve repair: conduits and human acellular nerve allograft

Nerve conduits and acellular nerve allograft offer efficient and convenient tools for overcoming unexpected gaps during nerve repair. Both techniques offer guidance for migrating Schwann cells and axonal regeneration though utilizing very different scaffolds. The substantially greater amount of animal and clinical data published on nerve conduits is marked by wide discrepancies in results that may be partly explained by a still poorly defined critical repair gap and diameter size. The available information on acellular allografts appears more consistently positive though this tool is also hampered by a longer but also limited critical length. This article reviews the current relative literature and examines pertinent parameters for application of both acellular allograft and nerve conduits in overcoming short nerve gaps.

Clinical applications of autografts, conduits, and allografts in repair of nerve defects in the hand: current guidelines

Traumatic nerve injuries are common conditions treated by hand surgeons, and the optimal treatment of a severed nerve requires providing a healthy wound bed, generous trimming to healthy nerve substance, and a minimal-tension approximation. The gold standard for repair of a critical nerve gap has been the nerve autograft. However, results are generally less favorable than direct suture. Autogenous and synthetic conduits and processed nerve allografts have been developed as less morbid and more convenient alternatives to autografts, but the reported outcomes have been uneven. Engineered neural tissues show great promise in inducing nerve regeneration across a gap.

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.

Update on nerve repair by biological tubulization

Many surgical techniques are available for bridging peripheral nerve defects. Autologous nerve grafts are the current gold standard for most clinical conditions. In selected cases, alternative types of conduits can be used. Although most efforts are today directed towards the development of artificial synthetic nerve guides, the use of non-nervous autologous tissue-based conduits (biological tubulization) can still be considered a valuable alternative to nerve autografts. In this paper we will overview the advancements in biological tubulization of nerve defects, with either mono-component or multiple-component autotransplants, with a special focus on the use of a vein segment filled with skeletal muscle fibers, a technique that has been widely investigated in our laboratory and that has already been successfully introduced in the clinical practice.

Peripheral nerve repair and reconstruction

When possible, direct repair remains the current standard of care for the repair of peripheral nerve lacerations. In large nerve gaps, in which direct repair is not possible, grafting remains the most viable option. Nerve scaffolds include autologous conduits, artificial nonbioabsorbable conduits, and bioabsorbable conduits and are options for repair of digital nerve gaps that are <3 cm in length. Experimental studies suggest that the use of allografts may be an option for repairing larger sensory nerve gaps without associated donor-site morbidity.

Collagen conduit versus microsurgical neurorrhaphy: 2-year follow-up of a prospective, blinded clinical and electrophysiological multicenter randomized, controlled trial

PURPOSE

To compare repair of acute lacerations of mixed sensory-motor nerves in humans using a collagen tube versus conventional repair.

METHODS

In a prospective randomized trial, we repaired the ulnar or the median nerve with a collagen nerve conduit or with conventional microsurgical techniques. We enrolled 43 patients with 44 nerve lacerations. We performed electrophysiological tests and hand function using a standardized clinical evaluation instrument, the Rosen scoring system, after 12 and 24 months.

RESULTS

Operation time using the collagen conduit was significantly shorter than for conventional neurorrhaphy. There were no complications in terms of infection, extrusion of the conduit, or other local adverse reaction. Thirty-one patients with 32 nerve lesions, repaired with collagen conduits or direct suture, attended the 24-month follow-up. There was no difference between sensory function, discomfort, or total Rosen scores. Motor scores were significantly better for the direct suture group after 12 months, but after 24 months, there were no differences between the treatment groups. There was a general further recovery of both motor and sensory conduction parameters at 24 months compared with 12 months. There were no statistically significant differences in amplitudes, latencies, or conduction velocities between the groups.

CONCLUSIONS

Use of a collagen conduit produced recovery of sensory and motor functions that were equivalent to direct suture 24 months after repair when the nerve gap inside the tube was 6 mm or less, and the collagen conduit proved to be safe for these nerve lacerations in the forearm.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic II.

Allograft reconstruction for digital nerve loss

PURPOSE

To investigate the outcomes of digital nerve repairs using processed nerve allograft for defects measuring 30 mm or less.

METHODS

Seventeen patients with 21 digital nerve lacerations in the hand underwent reconstruction with processed nerve allograft. Outcome data for 14 patients with 18 digital nerve lacerations were available for analysis. Postoperative outcome data were recorded at a minimum of 12 months and an average of 15 months. The average nerve gap measured 11 mm (range, 5-30 mm). Outcome measures included postoperative sensory examination as assessed by Semmes-Weinstein monofilaments and static and moving 2-point discrimination. Pain was graded using a visual analog scale throughout the recovery period. In addition, patients completed the Quick Disabilities of the Arm, Shoulder, and Hand survey before and after surgery.

RESULTS

Using Taras outcome criteria, 7 of 18 (39%) digits had excellent results, 8 of 18 (44%) had good results, 3 of 18 (17%) digits had fair results, and none had poor results. At final follow-up, Semmes-Weinstein monofilament testing results ranged from 0.08 g to 279 g. Quick Disabilities of the Arm, Shoulder, and Hand scores recorded at the patient's first postoperative visit averaged 45 (range, 2-80), and final scores averaged 26 (range, 2-43). There were no signs of infection, extrusion, or graft reaction.

CONCLUSIONS

The data suggest that processed nerve allograft provides a safe and effective alternative for the reconstruction of peripheral digital nerve deficits measuring up to 30 mm.

Evidence and techniques in rehabilitation following nerve injuries

Following upper extremity peripheral nerve injury and surgery, rehabilitation is essential to optimize sensorimotor function and outcome. This review presents the evidence and related literature regarding a few key topics related to rehabilitation following peripheral nerve injury and surgery.

Nerve allografts and conduits in peripheral nerve repair

Since the last update on nerve conduits and allograft in 2000, investigations have established the efficacy of these alternatives to autograft in the repair of small sensory neural gaps. However, limited insights into the biology of the regenerating nerve continue to preclude intelligent conduit design. Ongoing discoveries in neuroscience and biomaterial engineering hold promise for the eventual development of allograft and conduits with potential of surpassing nerve autografts in clinical efficacy. In this review, we summarize the history, recent advances, and emerging developments in nerve conduits and allograft.

Sensory recovery outcome after digital nerve repair in relation to different reconstructive techniques: meta-analysis and systematic review

Good clinical outcome after digital nerve repair is highly relevant for proper hand function and has a significant socioeconomic impact. However, level of evidence for competing surgical techniques is low. The aim is to summarize and compare the outcomes of digital nerve repair with different methods (end-to-end and end-to-side coaptations, nerve grafts, artificial conduit-, vein-, muscle, and muscle-in-vein reconstructions, and replantations) to provide an aid for choosing an individual technique of nerve reconstruction and to create reference values of standard repair for nonrandomized clinical studies. 87 publications including 2,997 nerve repairs were suitable for a precise evaluation. For digital nerve repairs there was practically no particular technique superior to another. Only end-to-side coaptation had an inferior two-point discrimination in comparison to end-to-end coaptation or nerve grafting. Furthermore, this meta-analysis showed that youth was associated with an improved sensory recovery outcome in patients who underwent digital replantation. For end-to-end coaptations, recent publications had significantly better sensory recovery outcomes than older ones. Given minor differences in outcome, the main criteria in choosing an adequate surgical technique should be gap length and donor site morbidity caused by graft material harvesting. Our clinical experience was used to provide a decision tree for digital nerve repair.

Type I collagen nerve conduits for median nerve repairs in the forearm

PURPOSE

To evaluate patients with median nerve damage in the distal forearm treated with type 1 collagen nerve conduits.

METHODS

Nine patients with damage to the median nerve in the distal forearm underwent treatment with a type 1 collagen nerve conduit. The nerve gaps ranged between 1 and 2 cm. An independent observer reexamined patients after treatment at a minimal follow-up of 14 months and a mean follow-up of 21 months. Residual pain was evaluated using a visual analog scale. Functional outcome was quantified by assessing static 2-point discrimination, nerve conduction velocity relative to the uninjured limb, and Disabilities of the Arm, Shoulder, and Hand outcome measure scoring. We also recorded quality of life measures including patients' perceived satisfaction with the results and return to work latency.

RESULTS

We observed no implant-related complications. Of 9 patients, 7 were free of pain, and the mean visual analog scale was 0.6. The mean Disabilities of the Arm, Shoulder, and Hand score was 6. The static 2-point discrimination was less than 6 mm in 3 patients, between 6 and 10 mm in 4 patients, and over 10 mm in 2 patients. Six patients reached a status of M4 or higher. Eight patients were satisfied with the procedure and would undergo surgery again.

CONCLUSIONS

This study indicates that purified type 1 bovine collagen conduits are a practical and efficacious method for the repair of median nerves in the distal forearm.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Functional outcome following nerve repair in the upper extremity using processed nerve allograft

PURPOSE

Reconstruction of peripheral nerve discontinuities with processed nerve allograft has become increasingly relevant. The RANGER Study registry was initiated in 2007 to study the use of processed nerve allografts in contemporary clinical practice. We undertook this study to analyze outcomes for upper extremity nerve repairs contained in the registry database.

METHODS

We identified an upper extremity-specific population within the RANGER Study registry database consisting of 71 nerves repaired with processed nerve allograft. This group was composed of 56 subjects with a mean age of 40 ± 17 years (range, 18-86 y). We analyzed data to determine the safety and efficacy of processed nerve allograft. Quantitative data were available on 51 subjects with 35 sensory, 13 mixed, and 3 motor nerves. The mean gap length was 23 ± 12 mm (range, 5-50 mm). We performed an analysis to evaluate response-to-treatment and to examine sensory and motor recovery according to the international standards for motor and sensory nerve recovery.

RESULTS

There were no reported implant complications, tissue rejections, or adverse experiences related to the use of the processed nerve allografts. Overall recovery, S3 or M4 and above, was achieved in 86% of the procedures. Subgroup analysis demonstrated meaningful levels of recovery in sensory, mixed, and motor nerve repairs with graft lengths between 5 and 50 mm. The study also found meaningful levels of recovery in 89% of digital nerve repairs, 75% of median nerve repairs, and 67% of ulnar nerve repairs.

CONCLUSIONS

Our data suggest that processed nerve allografts offer a safe and effective method of reconstructing peripheral nerve gaps from 5 to 50 mm in length. These outcomes compare favorably with those reported in the literature for nerve autograft, and exceed those reported for tube conduits.

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.