Usability of Nerve Tape: A Novel Sutureless Nerve Coaptation Device.

PURPOSE: Microsuture neurorrhaphy is technically challenging and has inherent drawbacks. This study evaluated the potential of a novel, sutureless nerve coaptation device to improve efficiency and precision. METHODS: Twelve surgeons participated in this study-six attending hand/microsurgeons and six trainees (orthopedic and plastic surgery residents or hand surgery fellows). Twenty-four cadaver arm specimens were used, and nerve repairs were performed at six sites in each specimen-the median and ulnar nerves in the proximal forearm, the median and ulnar nerves in the distal forearm, and the common digital nerves to the second and third web spaces. Each study participant performed nerve repairs at all six injury locations in two different cadaver arms (n = 12 total repairs for each participating surgeon). The nerve repairs were timed, tested for tensile strength, and graded for alignment and technical repair quality. RESULTS: A substantial reduction in time was required to perform repairs with the novel coaptation device (1.6 ± 0.8 minutes) compared with microsuture (7.2 ± 3.6 minutes). Device repairs were judged clinically acceptable (scoring "Excellent" or "Good" by most of the expert panel) in 97% of the repairs; the percentage of suture repairs receiving Excellent/Good scores by most of the expert panel was 69.4% for attending surgeons and 36.1% for trainees. The device repairs exhibited a higher average peak tensile force (7.0 ± 3.6 N) compared with suture repairs (2.6 ± 1.6 N). CONCLUSIONS: Nerve repairs performed with a novel repair device were performed faster and with higher technical precision than those performed using microsutures. Device repairs had substantially greater tensile strength than microsuture repairs. CLINICAL RELEVANCE: The evaluated novel nerve repair device may improve surgical efficiency and nerve repair quality.

Surgical Treatment of Symptomatic End-Neuroma With a New Bioresorbable Copolyester Nerve Capping Device: A Multicenter Prospective Cohort Study.

BACKGROUND: Neuroma-induced neuropathic pain is associated with loss of function and reduced quality of life. No consistently effective standard-of-care treatment has been defined. Neurocap, a bioresorbable nerve capping device, has been designed to isolate the nerve stump from surrounding tissues to reduce development of symptomatic end-neuromas. METHODS: Patients with peripheral symptomatic end-neuromas were included in a prospective, multicenter, single-arm design. Data were collected presurgery up till 24 months postsurgery. Eligible patients with neuromas were identified based on blocks using anesthetic. Intervention included surgical excision and capping of the transected proximal nerve end with the Neurocap. Main outcome measures were pain, function, recurrence of symptomatic neuroma, use of analgesics, and adverse events. RESULTS: In total, 73 patients with 50 upper-extremity and 23 lower-extremity end-neuromas were enrolled. End-neuromas were predominately located in the digits and lower leg. Statistical power of the study outcomes was preserved by 46 of 73 patients completing 24-month follow-up. The mean VAS-Pain score at baseline was 70.2 ± 17.8 (scale 0-100) and decreased significantly to 31 ± 32.5 (P < 0.001). Function significantly improved over time. The recurrence rate of confirmed symptomatic neuroma was low (2 of 98 capped nerves). Adverse event rate was low and included pain and infection; there were no unexpected device-related adverse events. Most patients reported lower use of nonsteroidal anti-inflammatory drugs, opioids, and antineuropathic medications at last follow-up compared with baseline. CONCLUSIONS: End-neuroma treatment with excision and capping resulted in long-term significant reduction in reported pain, disability, and analgesic medication use. Adverse event rate was low.

A Multicenter Prospective Randomized Comparison of Conduits Versus Decellularized Nerve Allograft for Digital Nerve Repairs.

PURPOSE: While there are advantages and disadvantages to both processed nerve allografts (PNA) and conduits, a large, well-controlled prospective study is needed to compare the efficacy and to delineate how each of these repair tools can be best applied to digital nerve injuries. We hypothesized that PNA digital nerve repairs would achieve superior functional recovery for longer length gaps compared with conduit-based repairs. METHODS: Patients (aged 18-69 years) presenting with suspected acute or subacute (less than 24 weeks old) digital nerve injuries were recruited to prticipate at 20 medical centers across the United States. After stratification to short (5-14 mm) and long (15-25 mm) gap subgroups, the patients were randomized (1:1) to repair with either a commercially available PNA or collagen conduit. Baseline and outcomes assessments were obtained either before or immediately after surgery and planned at 3-, 6-, 9-, and 12-months after surgery. All assessors and patients were blinded to the treatment arm. RESULTS: In total, 220 patients were enrolled, and 183 patients completed an acceptable last evaluable visit (at least 6 months and not more than 15 months postrepair). At last follow-up, for the short gap repair groups, average static two-point discrimination was 7.3 ± 2.8 mm for PNA and 7.5 ± 3.1 mm for conduit repairs. For the long gap group, average static two-point discrimination was significantly lower at 6.1 ± 3.3 mm for PNA compared with 7.5 ± 2.4 mm for conduit repairs. Normal sensation (American Society for Surgery of the Hand scale) was achieved in 40% of PNA long gap repairs, which was significantly more than the 18% observed in long conduit patients. Long gap conduits had more clinical failures (lack of protective sensation) than short gap conduits. CONCLUSIONS: Although supporting similar levels of nerve regeneration for short gap length digital nerve repairs, PNA was clinically superior to conduits for long gap reconstructions. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic I.

Evaluation of the Induced Membrane for Neurotrophic Factors.

PURPOSE: Despite gaining popularity as a bridge for small and moderate nerve gaps, an acellular nerve allograft (ANA) lacks many of the neurotrophic characteristics of a nerve autograft. Pseudomembranes induced to form around temporary skeletal spacers are rich in growth factors. Induced membranes may have beneficial neurotrophic factors which could support ANA. METHODS: Twenty-two male Sprague-Dawley rats underwent resection of 2 cm of the sciatic nerve. A silicone rod was inset in the defect of 11 experimental rats, and marking sutures only were placed in the nerve stumps of the remaining 11 control rats. After allowing 4 weeks for tissue maturation, tissue samples harvested from the induced membrane (experimental group) and the tissue bed (control group) were analyzed using Luminex multiplex assay to quantify differences in detectable levels of the following neurotrophic factors: nerve growth factor, glial-derived nerve factor, vascular endothelial growth factor, and transforming growth factor ß (TGF-ß) 1, 2, and 3, interleukin-1ß, and monocyte chemoattractant protein 1. RESULTS: No difference was detected between the control and experimental groups in levels of vascular endothelial growth factor. Higher levels of TGF-ß1, TGF-ß2, TGF-ß3, glial-derived nerve factor, nerve growth factor, monocyte chemoattractant protein 1, and interleukin-1ß were detected in the experimental group. CONCLUSIONS: In the setting of peripheral nerve injury, an induced membrane has higher levels of several neurotrophic factors that may support nerve regeneration compared to wound bed cicatrix. CLINICAL RELEVANCE: This investigation provides impetus for further study examining the utility of using a staged induced membrane technique in conjunction with delayed nerve grafting in reconstruction of some peripheral nerve defects.

Comparison of Nylon Suture Versus 2 Fibrin Glue Products for Delayed Nerve Coaptation in an Animal Model.

PURPOSE: To compare 2 different, commercially available fibrin glue products with nylon suture with regard to repair strength, muscle function, and axon regeneration after delayed nerve repair in an animal model. METHODS: A total of 120 Lewis rats underwent transection of the sciatic nerve. On day 3 after transection, the nerves were reexposed. A primary repair was performed on 40 rats from each group using nylon suture, Tisseel fibrin glue, or Evicel fibrin glue. On days 0, 3, and 7 after repair, 10 rats from each group underwent burst strength testing. Seventy days after repair, 10 rats from each group underwent functional muscle testing and histomorphic analysis of the nerve, with the contralateral limb serving as the control. RESULTS: There was no significant difference in burst strength among the groups on days 0 and 3. On day 7, the burst strength of the Evicel and nylon suture groups was significantly greater than that of the Tisseel group. There were 5 total coaptation failures in both fibrin glue groups and none in the suture group. Seventy days after repair, tetanic muscle strength, muscle mass, axon inner diameter, and g-ratio were equivalent among all groups. Axon counts were equivalent between the nylon suture and Evicel groups, although in the nylon group axon counts were higher than for the Tisseel group. CONCLUSIONS: In an animal model with a 3-day delay in nerve repair, although dehiscences occurred, when the initial repair held, fibrin glue was not inferior to nylon suture with regard to repair strength and muscle recovery. CLINICAL RELEVANCE: Historical concerns regarding spontaneous fibrin glue-based nerve repair dehiscences are well-founded. However, when coaptation is maintained, commercially available fibrin glues support nerve regeneration.

Side-to-side supercharging nerve allograft enhances neurotrophic potential.

INTRODUCTION: Critical limitations of processed acellular nerve allograft (PNA) are linked to Schwann cell function. Side-to-side bridge grafting may enhance PNA neurotrophic potential. METHODS: Sprague-Dawley rats underwent tibial nerve transection and immediate repair with 20-mm PNA (n = 33) or isograft (ISO; n = 9) or 40-mm PNA (n = 33) or ISO (n = 9). Processed acellular nerve allograft groups received zero, one, or three side-to-side bridge grafts between the peroneal nerve and graft. Muscle weight, force generation, and nerve histomorphology were tested 20 weeks after repair. Selected animals underwent neuron back labeling with fluorescent dyes. RESULTS: Inner axon diameters, g-ratios, and axon counts were smaller in the distal vs proximal aspect of each graft (P < .05). Schwann cell counts were greater, with a lower proportion of senescent cells for groups with bridges (P < .05). Retrograde labeling demonstrated that 6.6% to 17.7% of reinnervating neurons were from the peroneal pool. DISCUSSION: Bridge grafting positively influenced muscle recovery and Schwann cell counts and senescence after long PNA nerve reconstruction.

Viral vector delivery of follistatin enhances recovery of reinnervated muscle.

INTRODUCTION: Poor recovery following nerve repair is due to progressive temporal loss of muscle function. Follistatin (FS), a glycoprotein with anabolic properties, may enhance muscle recovery following reinnervation. METHODS: Seventy-two male Sprague-Dawley rats underwent temporary (3 or 6 month) denervation or sham denervation. After reinnervation, rats were administered adeno-associated viral vectors expressing FS deoxyribonucleic acid (isoform FS-317) injected into the target muscle or sham treatment. Final assessment included muscle function testing, muscle histomorphology, nerve histomorphology, and FS protein quantification. RESULTS: FS improved muscle mass and type IIB muscle fiber size, and increased G-ratios and mean axon diameter in the 6-month temporary denervation group (P < .05). Elevated FS protein levels were detected in treated muscle (P < .05). FS increased satellite cell counts following temporary denervation and repair (P < .05). DISCUSSION: FS treatment had anabolic, neurotrophic, and satellite cell stimulatory effects when administered following prolonged (6-month) temporary denervation and repair.

The Use of a Lumbrical Muscle Flap for Treatment of Chronic Tenocutaneous Fistula.

Tenocutaneous fistulas after trauma or open release of the A1 pulley provide a unique reconstructive challenge. We describe the use of a lumbrical muscle turnover flap as a novel technique for managing these wounds and present its successful use in a patient with a tenocutaneous fistula after A1 pulley release of the middle finger. This flap provides a simple, local reconstructive option in patients with an array of palmar wounds that have failed conservative management.

Effect of Reverse End-to-Side (Supercharging) Neurotization in Long Processed Acellular Nerve Allograft in a Rat Model.

PURPOSE: Processed acellular nerve allograft (PNA) has been suggested as a convenient tool for overcoming short and medium nerve defects. Although the clinical implications are unclear, animal data suggest that PNA becomes less effective at longer lengths. Although reverse or supercharging end-to-side nerve transfer may improve the neurotrophic potential in chronically denervated nerve tissue, the application of this strategy to long acellular nerve allograft has not been previously investigated. We hypothesized that supercharging acellular nerve allograft would increase its effective length. METHODS: Sprague-Dawley and Thy1-green fluorescent protein Sprague-Dawley rats underwent transection of the tibial nerve, followed by immediate repair with 20-, 40-, or 60-mm acellular nerve allografts processed identically to commercially available human acellular nerve allograft (AxoGen, Inc., Alachua, FL) or isograft. Half of the allograft group was supercharged with a reverse end-to-side transfer from the ipsilateral peroneal nerve. At 10 weeks, the reconstructed nerve in the Thy1-green fluorescent rat groups were exposed and examined under a fluorescence-enabled microscope. At 20 weeks, the remaining rats underwent motor testing and tissue harvest for morphological examination. RESULTS: In comparison with a nonenhanced allograft, supercharging had a statistically significant positive impact on the reinnervated muscle normalized force generation and distal axon counts for all graft sizes. Muscles in the supercharged group were heavier than those in the allograft group for the 40-mm-length grafts and G-ratio measurements were higher in the supercharged allograft group for 60-mm-length grafts only. CONCLUSIONS: This study supports that hypothesis that supercharging nerve transfer improves axon regeneration within PNA. CLINICAL RELEVANCE: When an appropriate donor nerve is available, supercharging nerve transfer may improve nerve regeneration in PNA across long nerve defects.

Soft Tissue Atrophy Related to Corticosteroid Injection: Review of the Literature and Implications for Hand Surgeons.

Corticosteroid injections (CIs) are frequently used by hand surgeons to treat a wide range of pathology including de Quervain tenosynovitis and lateral epicondylitis. Although generally viewed as a benign modality, and a way to potentially avoid or postpone surgical intervention, common complications from CI should be considered and discussed with patients before the procedure. One such complication is local soft tissue atrophy and hypopigmentation after injection. We discuss the incidence of soft tissue-related adverse effects from CI, the pathophysiology and influence of different steroid preparations on soft tissues, and potential treatment options once atrophy has occurred.

Tendon Adhesions: A Novel Method of Objectively Measuring Adhesions by Assessing Tendon Glide Through a Soft Tissue Envelope in a Rat Model.

PURPOSE: To develop a rat model of extra-synovial tendon adhesions that will enable accurate testing of scar barriers and adhesion inhibiting treatments to facilitate future research. METHODS: Thirty-six 6-month-old male Sprague-Dawley rats were randomized to one of the 3 groups of 12. In Group A, the middle one-third portion of the left Achilles tendon was excised. In Group B, the tendon and soft tissue bed was abraded with steel wool. In Group C, a silk suture was sewn along the tendon. The right hind limbs served as controls. At 4 weeks, biomechanical testing was performed on the bilateral hind limbs. The Achilles tendon was cut at the gastrocnemius-tendon junction proximal to the "adhesion zone" (or analogous level in the control limb). The calcaneal insertion of the Achilles was attached to a tensiometer. The force needed to pull the tendon out of its soft tissue envelope at a fixed rate was measured. RESULTS: Three rats were excluded because of complications during data collection. Pair-wise comparison testing was performed, comparing the mean peak force to pull the Achilles tendon from its soft tissue envelope in 33 control limbs and the contralateral limb from each group. The average peak force for the cut tendon group (A) was 20.1 N, 18.8 N in the steel wool group (B), and 21.1 N in the suture group (C). The average peak force in the control limbs was 15.6 N. There was a significant difference noted in peak forces between the control limbs and each experimental group. CONCLUSIONS: A consistent and statistically increased force was necessary to pull a rodent Achilles tendon from an adhesion-induced tissue bed compared with controls. No statistical difference was detected between experimental groups. CLINICAL RELEVANCE: Our study demonstrates an objective method of biomechanical tendon adhesion assessment in a rat model.

Appropriateness of patients transferred with orthopedic injuries: experience of a level I trauma center.

BACKGROUND: Trauma patients are frequently transferred to a higher level of care for specialized orthopedic care. Many of these transfers are not necessary and waste valuable resources. The purpose of this study was to quantify our own experience and to assess the appropriateness of orthopedic transfers to a level I trauma center emergency department. METHODS: A retrospective review of orthopedic emergency department transfers to a level I trauma center was performed. Data collected included time of transfer, injury severity score (ISS), age, gender, race, orthopedic coverage at transfer institution, and insurance status. Two orthopedic trauma surgeons graded the appropriateness of transfer. A weighted logistic regression model was used to compare dependent and independent variables. RESULTS: A total of 324 patient transfers were reviewed; 65 (20.1%) of them were graded as inappropriate. There was no statistically significant relationship between appropriateness of transfer and age, availability of orthopedic coverage, night/weekend transfer, or insurance status. Regression analysis showed that only ISS (OR 1.130, p = .008) and "polytrauma" (OR 25.39, p < .0001) designation were associated with increased odds ratio of appropriate transfer. The kappa coefficient for inter-rater reliability between the two raters was 0.505 (95% CI, 0.388-0.623) reflecting moderate agreement. CONCLUSION: Inappropriate transfers create a significant medical burden to our health care system using valuable resources. Our study found similar results of inappropriate transfers compared to previous studies. However, we did not find a relationship between insurance status or nights/weekends and transfer appropriateness.

Does partial muscle reinnervation preserve future re-innervation potential?

INTRODUCTION: Late revision nerve surgery for incomplete motor recovery due to partial reinnervation would improve muscle function if all muscle fibers were protected from developing denervation atrophy. METHODS: Sixty immature Sprague-Dawley rats underwent the following tibial nerve manipulations (n = 15/group): group A, partial denervation (two thirds of nerve resected and the remaining one third crushed), revision repair at 8 months; group B, partial denervation; group C, complete denervation, immediate reconstruction; group D, complete denervation, reconstruction at 8 months; and group E, control. Final testing at 11 months included muscle force, weight, and histology. RESULTS: Muscle weight was significantly (P < 0.05) different among all groups (highest to lowest: E > B > C > A > D), and force was significantly lower in groups A and D compared with E. Muscle fiber cross-sectional area was statistically smaller in group A than in groups B, C, or E. DISCUSSION: Partial reinnervation still allowed substantial muscle recovery, but it did not preserve the non-innervated muscle fibers. Muscle Nerve 56: 1143-1148, 2017.

Technical Assessment of Connector-Assisted Nerve Repair.

PURPOSE: Clinical outcomes of nerve repair have not substantially improved over the last several decades. Although clearly a multifactorial problem, basic principles including proper fascicular alignment are not always realized. The use of short conduits as connectors may enhance nerve alignment by entubulating and directing the approximation of nerve ends. METHODS: Ten hand surgeons (5 experienced and 5 inexperienced) performed a series of in vitro human cadaver nerve repairs. Three small-diameter (2 mm), 3 medium-diameter (3-4 mm), and 3 large-diameter (5-6 mm) nerves were repaired (under 10× magnification) utilizing each of 3 techniques: suture-only, connector-only (sutures placed through the ends of the connector), and connector-assisted (alignment sutures at the nerve interface plus connector). Three judges (blinded to who performed the repairs) assessed each repair for fascicular alignment based on predetermined qualitative scales. RESULTS: Across all surgeons, 23 of 30 connector-assisted repairs were judged good or excellent versus 18 of 30 of the suture-only and 13 of 30 of the connector-only repairs. Experienced surgeons in general did better repairs and in particular were more likely to obtain superior alignment for conduit-only repairs (73.3% vs 13.3% good or excellent) and suture-only repairs (73.3% vs 46.7% good or excellent) and were not statistically different for connector-assisted repairs (86.7% vs 66.7% good or excellent) compared with inexperienced surgeons. CONCLUSIONS: In a cadaver nerve model, there was no significant difference in the technical alignment of conduit-assisted repairs between experienced and inexperienced surgeons whereas inexperienced surgeons were more likely to achieve inadequate alignment with suture-only or conduit-only repairs. CLINICAL RELEVANCE: Connector-assisted repairs combining suture-approximation and entubulation may improve the technical alignment of nerve repairs performed, especially by less-experienced surgeons.

Reattachment of flexor digitorum profundus avulsion: biomechanical performance of 3 techniques.

PURPOSE: To investigate whether inclusion of the volar plate in repair of flexor digitorum profundus avulsions increases the strength of the repair and resists gapping. METHODS: Cadaveric fingers (n = 18) were divided into 3 equal groups. The first technique involved 2 micro-suture anchors only (A). The second used only volar plate repair (VP). The third group was a hybrid, combining a micro-suture anchor with volar plate augmentation (AVP). Specimens were loaded cyclically to simulate passive motion rehabilitation before being loaded to failure. Clinical failure was defined as 3 mm of gapping, and physical failure as the highest load associated with hardware failure, suture breakage, anchor pullout, or volar plate avulsion. RESULTS: Gapping throughout cycling was significantly greater for the A group than VP and AVP with no difference detected between VP and AVP groups. Gapping exceeded 3 mm during cycling of 3 A specimens, but in none of the VP or AVP specimens. Load at clinical and physical failure for A was significantly lower than for VP and AVP, whereas no difference was detected between VP and AVP. CONCLUSIONS: In this cadaveric model, incorporating the volar plate conferred a significant advantage in strength, increasing the mean load to physical failure by approximately 100 N. CLINICAL RELEVANCE: According to previous biomechanical studies, current reconstructive strategies for flexor digitorum profundus zone I avulsions are not strong enough to withstand active motion rehabilitation. We demonstrated the potential use of volar plate augmentation and the prospective advantageous increase in strength in this cadaveric model. In vivo performance and effects on digital motion are not known.

Unicortical PEEK inset locking fixation for metacarpal fractures: a biomechanical study.

PURPOSE: There are numerous constructs employed in the treatment of metacarpal fractures with varying degrees of success. While plate fixation commonly involves dorsal application of a bicortical non-locking plate, there has been recent exploration of other fixation options including unicortical locked plating. The purpose of this study was to evaluate the biomechanical integrity of a polyetheretherketone (PEEK) inset locking plate and, in doing so, compare it to standard plate fixation (utilizing a clinically proven bicortical non-locking titanium plate) in a simulated porcine metacarpal fracture model. METHODS: Reproducible mid-shaft fractures were created in porcine second metacarpals. The fractured specimens were reduced and plated with either a bicortical non-locking plate or a unicortical locking plate with a PEEK locking design. Constructs were then loaded to failure in the same fashion as performed to create the fracture. Peak load was measured as the apex on the load-to-failure deflection curve. Stiffness was calculated as the linear slope on the load-to-failure deflection curve. Data were analyzed via Student's t test. RESULTS: Unicortical locking constructs failed at 344 ± 119 N, while bicortical non-locking constructs were found to fail at 277 ± 101 N (p = 0.19). The unicortical locking constructs demonstrated a stiffness of 80 ± 36 N/mm compared with the bicortical non-locking constructs (69 ± 36 N/mm) although again the difference was not found to be statistically different (p = 0.49). CONCLUSION: Based on this study, a locked plating construct using a polymer mechanism provides an interesting new locking fixation method for small bone fractures and with our limited number of specimens tested, provided at least a similar strength and rigidity profile in comparison with bicortical fixation in the treatment of metacarpal fractures.

Nerve Allografts: Current Utility and Future Directions.

Processed nerve allograft is a widely accepted tool for reconstructing peripheral nerve defects. Repair parameters that need to be considered include gap length, nerve diameter, nerve type (motor, sensory, or mixed), and the soft tissue envelope. Although the use of processed nerve allograft must be considered based on each unique clinical scenario, a rough algorithm can be formed based on the available animal and clinical literature. This article critically reviews the current surgical algorithm, defines the role of processed nerve allograft compared with nerve autograft, and discusses how this role may change in the future.

Reverse Shoulder Arthroplasty for Irreparable Rotator Cuff Tear After Radial to Axillary End-to-Side Transfer: A Case Report.

CASE: A 60-year-old man sustained a massive irreparable rotator cuff tear and axillary nerve palsy with deltoid dysfunction after an anterior shoulder dislocation. He underwent staged reverse end-to-side radial-to-axillary nerve transfer with return of deltoid function allowing for subsequent reverse shoulder arthroplasty. At 1 year postoperatively, he returned to full activity. CONCLUSION: Irreparable rotator cuff tears complicated by axillary nerve palsy can be effectively treated with a staged approach of nerve transfer followed by reverse shoulder arthroplasty.

Revision of failed distal interphalangeal arthrodesis complicated by retained headless screw.

Arthrodesis of the distal interphalangeal joint is a well-accepted treatment for painful arthritis. Although headless screw fixation across the distal interphalangeal joint is an overall effective method for achieving bony union, failures and nonunions still occur. We present a salvage technique to address both the retained headless screw within the medullary canal as well as the persistent nonunion.