The management of digital nerve injuries

Conduit/Wrap Repairs to Digital Nerves Provide Residual Strength After Peak Loading

BACKGROUND

Many techniques are used for digital nerve repair, most commonly coaptation by sutures. Nerve repairs must be strong while offering an environment for nerve regeneration. Sutures can damage the nerve and thereby limit growth and regeneration. Sutures can rip and cause sudden catastrophic failure. Fibrin glue and conduit-wraps allow a good environment for growth, but neither provides much strength. A benefit to conduit repair would arise if the repair maintained integrity after the peak load so that the path for regrowth stayed in place. The goal for this study was to determine whether conduit with glue provides continued strength after a maximum load is reached.

METHODS

Digital cadaveric nerves were harvested and repaired with 2 epineurial sutures, conduit, and fibrin glue in all combinations. Tests to failure were performed, gap displacement between nerve ends recorded, and the postpeak load energy to dissociation of the nerve and conduit was calculated.

RESULTS

Conduit with glue and 2 sutures at the end had the greatest energy and displacement after the peak load but was not significantly different than conduit with glue and 1 suture. Conduit with glue alone obtained statistically the same displacement as conduit with glue and 2 sutures. Conduit, with or without glue, and 2 sutures was statistically the same as suture only repair for peak load.

CONCLUSION

Conduit/wrap maintains a load capacity and a path for nerve regeneration after the peak. Suture at the ends of conduit, not at the coaptation site, reduces damage at the point of injury.

Outcome After Reconstruction of 43 Digital Nerve Defects With Muscle-in-Vein Conduits

PURPOSE

Muscle-in-vein conduits provide an alternative for bridging digital nerve defects when tension-free suture is not possible. Low donor site morbidity and absence of additional costs are favorable advantages compared with autografts or conduits.

METHODS

We retrospectively reviewed 37 patients with 43 defects of proper palmar digital nerves. Primary repair by muscle-in-vein conduits was performed in 22 cases, whereas 21 cases underwent secondary reconstruction. Recovery of sensibility was assessed using static and moving 2-point discrimination and Semmes-Weinstein monofilament testing. Results were compared with the contralateral side serving as a control. Outcome data were stratified according to international guidelines and evaluated for differences in terms of age, gap length, time of reconstruction, and concomitant injuries.

RESULTS

The median gap length was 20 mm (range, 9-60 mm). After a median follow-up of 25.0 months (interquartile range, 29.0 months), the median static and moving 2-point discrimination were 7.0 mm and 5.0 mm (interquartile range, 3.0 mm), respectively. The evaluation with Semmes-Weinstein monofilament revealed a median reduction of sensibility of 2 levels compared with the contralateral side. According to the American Society for Surgery of the Hand guidelines, 81.4% of the results were classified as excellent or good, whereas fair and poor results were noted in 9.3% of the cases each. The modified Highet and Sander's criteria rated complete clinical recovery in 13 cases; 23 results were regarded as S3+.

CONCLUSIONS

Muscle-in-vein conduits can be considered for primary and secondary reconstruction of digital nerves. Successful sensory recovery in terms of measurable 2-point discrimination was achieved in 91% of all cases.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Advances of Direct Peripheral Nerve Repair Techniques: Do We Already Have Enough Scientific Evidence?

Purpose

To systematically review the evidence of direct peripheral nerve repair techniques and to determine any differences in outcomes that would guide rational treatment. Additionally, we compare the results and outcomes of these studies and find future directions for peripheral nerve repair techniques.

Methods

We searched PubMed, Virtual Health Library, and Embase databases to identify articles involving direct peripheral nerve techniques. We analyzed and compared the results and outcomes of these techniques. We also aimed to look for the differences in outcomes that would guide the current and future treatments.

Results

We identified 1390 articles, and 19 met our criteria with evidence ranging from level I to level IV. The nerve repair techniques included direct repair, epineural repair, fascicular repair, and group fascicular repair. These nerve techniques are based on the surgeons' personal experience. The results and the outcome of these studies were based on prognostic factors and not on surgical techniques. Few studies compared the surgical techniques and found no significant difference in nerve repair techniques.

Conclusions

Analyzing all direct peripheral nerve techniques and literature of all levels of evidence, our data show no significant difference between different suturing techniques. Currently, there is a lack of scientific evidence on the best direct peripheral nerve repair techniques. Therefore, we need more research to understand the rational treatment methods for peripheral nerve injuries.

Level of evidence

IV.

Nerve regeneration conduit from inverted human umbilical cord vessel in the treatment of proper palmar digital nerve sections

Treatment of digital nerve injuries, particularly in case of a gap, is challenging. Recovery of finger sensitivity is often incomplete and can impair personal and occupational activity. The need for better nerve regeneration has given rise to alternative treatments such as nerve conduits. This study aimed to evaluate the safety and efficacy of a conduit of freeze-dried inverted human umbilical cord vessel for regeneration in digital nerve section. Twenty-three patients with a mean nerve gap of 6.11 mm (range 2-30 mm and static 2-point discrimination (s2PD) > 15 mm underwent surgical repair of digital nerve section using a nerve regeneration conduit. The primary endpoint was recovery of sensitivity after conduit implantation. Secondary endpoints comprised progression of pain, functional symptoms, pressure threshold, hand-specific symptoms and disabilities, and restored innervation. Mean follow-up was 10.1 ± 4.1 months (range 1-14 months). Sensitivity recovered progressively in the months following implantation. There was a mean decrease of 8.54 mm in s2PD between baseline and last follow-up (p < 0.001). Complete innervation recovered in 83.3% of cases at last follow-up. Pressure threshold and hand-related quality of life improved significantly and symptoms due to nerve sectioning (pain, cold intolerance, hypoesthesia, hyperesthesia) resolved almost completely. There were no safety issues related to the nerve conduit. These results indicate that freeze-dried inverted human umbilical vessels can be a safe and effective option as conduit for digital nerve regeneration.

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.

Ultrasound features of traumatic digital nerve injuries of the hand with surgical confirmation

OBJECTIVE

Characterize the appearance of digital nerve injuries in different ultrasound planes and correlate the presence and size of neuromas with time from injury.

MATERIALS AND METHODS

Surgically confirmed nerve injuries were retrospectively evaluated. Appearances of the nerve injury in the available imaging planes were reviewed by two readers. Associations between presence and size of neuroma with time from injury were analyzed.

RESULTS

Injuries of 29 digital nerves (3 incomplete lacerations, 17 complete lacerations, 6 with 7 stump neuromas, 3 neuromas-in-continuity) noted on ultrasound were surgically confirmed. Among the 20 lacerations, long-axis images were obtained in 15, of which 10 depicted the injury and 4 did not. Among the 10 depicting the injury in long axis, 2 showed a discrete gap, and 7 showed the nerve obscured by laceration tissue without a gap. In short axis, the nerve injury was visible in all 20, and nerve laceration was seen as a discrete gap in 2, and obscuration by laceration tissue in 14. Neuromas were hypoechoic and well-defined. There was a positive association between time and presence of neuroma (OR = 1.3, p = 0.002). Correlations between time and cross-sectional area (r_s = 0.45) and volume (r_s = 0.57) of neuromas were moderately positive.

CONCLUSION

Ultrasound long axis may be less useful, and those short axis may be more reliable for assessing digital nerve injuries than previously reported. Neuromas are hypoechoic and well-defined, and their size can vary based on time from injury.

Use of a vascularized dorsal sensory branch of an ulnar nerve flap for repairing a proper digital nerve with coverage of a volar soft tissue defect: Report of two cases

To repair a short nerve gap, autograft, allograft, autogenous, or synthetic conduits are selected, but a vascularized nerve autograft is preferred to obtain a reliable postoperative outcome in the case of an unfavorable wound bed. The purpose of this report is to describe and evaluate two cases of repair of a proper digital nerve and volar soft tissue defect with a vascularized dorsal sensory branch of an ulnar nerve flap. The cases of two men, 40 and 20 years old, who suffered index finger defects due to crush lacerations that required a flap and a nerve graft, are presented. A 4.0 cm × 2.0 cm and a 3.2 cm × 1.6 cm flap, which were nourished by the perforators from the ulnar proper digital artery of the little finger, were elevated from the ulnar side of fifth metacarpal bone head and transferred for coverage of the soft tissue defect. A 4.6-cm and a 3.0-cm vascularized nerve graft was interposed in the nerve gap. The patients' postoperative courses were uneventful, and both patients had no complaints related to the donor site. Static and moving two-point discrimination were 8 and 6 mm, respectively, at 6 months after surgery in the first case and 5 and 3 mm, respectively, at 9 months after surgery in the second case. This flap, which could be elevated in the same operative field with a nerve having similar diameter to that of the proper digital nerve, was useful for repair of a finger volar tissue defect.

Secondary Surgery Following Replantation and Revascularization

Secondary surgery following digital replantation and revascularization is common and is often performed to improve range of motion, tendon gliding, sensibility, and/or contour. In this article, the authors present the most common secondary procedures performed after digital replantation or revascularization and discuss current techniques. The importance of patient selection and postoperative compliance with ongoing hand therapy is paramount to achieving good outcomes.

Pediatric Replantation and Revascularization

Replantation and revascularization in the pediatric extremity has unique challenges that provide a fertile field of research and clinical experience. Children regenerate peripheral nerves rapidly, resulting in good sensory and motor function. They adapt well to functional deficits and mismatch errors of reinnervation. The technical aspects of microsurgical care in children can be challenging because the structures are small. Additional technical challenges include preservation of growth centers, prevention of vasospasm, protection of the reconstruction, and psychosocial care. Despite these challenges, children show excellent functional outcomes with minimal complications.

Flexor Tenosynovitis

For patients with suspected flexor tenosynovitis, the mainstay of diagnosis is a thorough history and physical examination. The examination is guided by evaluating the patient for Kanavel's four cardinal signs. Empiric antibiotics should be started immediately on diagnosis covering skin flora and gram-negative bacteria. Typically, surgery is required. Appropriate exposure is required for adequate treatment and incisions should be tailored to preserve areas of skin compromised from draining sinuses and abscess pressure. Diabetes mellitus and peripheral vascular disease place patients at higher risk of poor outcomes including stiffness and amputation; early administration of antibiotics is the intervention that correlates most closely with good outcomes.

Challenges Posed by Delayed Presentation of Mutilating Hand Injuries

Management of mutilating hand injury is a challenge for any hand surgeon. Delay in presentation makes management even more challenging, usually because of inadequate initial assessment, inadequate debridement leading to infection, and secondary loss of tissues from exposure and desiccation. The aim is to obtain a functional hand by radical debridement, adequate assessment of the injury, appropriately timed reconstruction, and physiotherapy and rehabilitation. The hand surgeon must pay attention to the appearance of the hand by elimination of deformities, unsightly scars and bulky flaps to help to restore confidence in the patient to face the demands of daily living.

Nerve Repair and Nerve Grafting

Direct repair and nerve autografting are primary options in the treatment of upper extremity peripheral nerve injuries. Deciding between these surgical options depends on the mechanism of injury, time since injury, and length of repair defect. Principles of direct repair and nerve autografting are reviewed. Finally, a literature-based review of the outcomes of upper extremity peripheral nerve repair and autografting is provided. Taken together, this article provides relevant and recent data for surgeons regarding patient selection, technique selection, surgical technique, surgical outcomes, and prognostic factors that will aid surgeons treating patients with upper extremity peripheral nerve injuries.