Publications by authors named "Samuel O Poore"

64 Publications

Effect of Nimodipine and Botulinum Toxin A on Peripheral Nerve Regeneration in Rats: A Pilot Study.

J Surg Res 2021 Apr 7;264:208-221. Epub 2021 Apr 7.

University of Wisconsin School of Medicine and Public Health, Division of Plastic Surgery, Department of Surgery, Madison, Wisconsin. Electronic address:

Background: Peripheral nerve damage is a frequent problem, with an estimated 2.8%-5.0% of trauma admissions involving peripheral nerve injury. End-to-end, tension-free microsurgical repair (neurorrhaphy) is the current gold standard treatment for complete transection (neurotmesis). While neurorrhaphy reapproximates the nerve, it does not address the complex molecular regenerative process. Evidence suggests that botulinum toxin A (BTX) and nimodipine (NDP) may improve functional recovery, but mechanisms of action remain unknown.

Methods: This research investigates BTX and NDP for their novel capacity to improve neural regeneration in the setting of neurorrhaphy using a Lewis rat tibial nerve neurotmesis model. In a triple-masked, placebo-controlled, randomized study design, we compared functional (rotarod, horizontal ladder walk), electrophysiological (conduction velocity, duration), and stereological (axon count, density) outcomes of rats treated with: NDP+saline injection, BTX+NDP, Saline+placebo, and BTX+placebo. Additional controls included sham surgery +/- BTX.

Results: NDP+saline outperformed other treatment groups in the ladder walk. This group had the fewest deep slips (15.07% versus 30.77% in BTX+NDP, P = 0.122), and the most correct steps (70.53% versus 55.58% in BTX+NDP, P = 0.149) in functional testing. NDP+saline also had the fastest nerve conduction velocity (0.811m/s versus 0.598m/s in BTX+NDP, P = 0.126) among treatment groups. BTX+NDP had the highest axon count (10,012.36 versus 7,738.18 in NDP+Saline, P = 0.009).

Conclusion: This study is the first to test NDP with BTX in a multimodal assessment of nerve recovery following neurotmesis and neurorrhaphy. NDP outperformed BTX+NDP functionally. Future work will focus on nimodipine in an effort to improve nerve recovery in trauma patients.
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http://dx.doi.org/10.1016/j.jss.2021.02.016DOI Listing
April 2021

Evaluation of Racial Disparities in Postoperative Outcomes Following Breast Reconstruction at a Single Institution in Wisconsin.

WMJ 2021 Mar;120(S1):S42-S47

University of Wisconsin School of Medicine and Public Health, Division of Plastic Surgery, Madison, Wisconsin,

Introduction: Breast cancer is the most common cancer in women in Wisconsin. Evidence demonstrates that non-White racial minorities in the United States exhibit a higher mortality rate and more advanced or aggressive presentations of the disease than their White counterparts. Postmastectomy breast reconstruction remains essential to the treatment and recovery of these patients; however, racial disparities in the receipt of reconstruction are evident. This study evaluates the presence of racial disparities in postoperative outcomes of breast reconstruction at a single institution in Wisconsin.

Methods: An institutional review board-exempt retrospective study of postoperative outcomes was performed using a single institution's National Surgical Quality Improvement Program Registry to identify patients who underwent autologous or prosthesis-based breast reconstruction following mastectomy. Patient demographic, preoperative, operative, and postoperative variables were recorded. Postoperative outcomes in relation to self-reported race were evaluated using univariate analysis and propensity score matching.

Results: A total of 1,140 patients were included (1,092 White vs 48 non-White), with fewer non-White patients undergoing reconstruction. Patients of non-White race demonstrated a higher incidence of morbid obesity (4.4% White vs 12.5% non-White,  = 0.010) and bleeding disorders (0.3% White vs 4.2% non-White,  < 0.001). No association between self-reported race and postoperative complication was found.

Conclusion: This study did not reveal racial disparities in postoperative outcomes of breast reconstruction at a single institution in Wisconsin; however, non-White patients were less likely to undergo reconstruction. Further research into the underlying causes of unequal access to care, influence of insurance, effect of structural racism, and impact of physician- and patient-associated factors is warranted.
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March 2021

Improving the Selectivity of an Osseointegrated Neural Interface: Proof of Concept For Housing Sieve Electrode Arrays in the Medullary Canal of Long Bones.

Front Neurosci 2021 15;15:613844. Epub 2021 Mar 15.

Division of Plastic Surgery, Department of Surgery, University of Wisconsin - Madison, Madison, WI, United States.

Sieve electrodes stand poised to deliver the selectivity required for driving advanced prosthetics but are considered inherently invasive and lack the stability required for a chronic solution. This proof of concept experiment investigates the potential for the housing and engagement of a sieve electrode within the medullary canal as part of an osseointegrated neural interface (ONI) for greater selectivity toward improving prosthetic control. are that (A) the addition of a sieve interface to a cuff electrode housed within the medullary canal of the femur as part of an ONI would be capable of measuring efferent and afferent compound nerve action potentials (CNAPs) through a greater number of channels; (B) that signaling improves over time; and (C) that stimulation at this interface generates measurable cortical somatosensory evoked potentials through a greater number of channels. The modified ONI was tested in a rabbit ( = 1) amputation model over 12 weeks, comparing the sieve component to the cuff, and subsequently compared to historical data. Efferent CNAPs were successfully recorded from the sieve demonstrating physiological improvements in CNAPs between weeks 3 and 5, and somatosensory cortical responses recorded at 12 weeks postoperatively. This demonstrates that sieve electrodes can be housed and function within the medullary canal, demonstrated by improved nerve engagement and distinct cortical sensory feedback. This data presents the conceptual framework for housing more sophisticated sieve electrodes in bone as part of an ONI for improving selectivity with percutaneous connectivity toward improved prosthetic control.
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http://dx.doi.org/10.3389/fnins.2021.613844DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8006940PMC
March 2021

The Impact of Prior Abdominal Surgery on Complications of Abdominally Based Autologous Breast Reconstruction: A Systematic Review and Meta-Analysis.

J Reconstr Microsurg 2021 Mar 1. Epub 2021 Mar 1.

Department of Surgery, Division of Plastic Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.

Background:  Approximately half of all patients presenting for autologous breast reconstruction have abdominal scars from prior surgery, the presence of which is considered by some a relative contraindication for abdominally based reconstruction. This meta-analysis examines the impact of prior abdominal surgery on the complication profile of breast reconstruction with abdominally based free tissue transfer.

Methods:  Literature search was conducted using PubMed, Scopus, and Web of Science. Included studies examined patients with a history of prior abdominal surgery who then underwent abdominally based free flap breast reconstruction. Prior liposuction patients and those with atypical flap designs were excluded. The Newcastle-Ottawa Scale was used to assess study quality. Flap complications included total and partial flap loss, fat necrosis, infection, and reoperation. Donor-site complications included delayed wound healing, infection, seroma, hematoma, and abdominal wall morbidity (hernia, bulge, laxity). Relative risk and 95% confidence intervals (CIs) between groups were calculated. Forest plots, statistic heterogeneity assessments, and publication bias funnel plots were produced. Publication bias was corrected with a trim-and-fill protocol. Overall effects were assessed by fixed-effects and random-effects models.

Results:  After inclusion and exclusion criteria were applied, 16 articles were included for final review. These included 14 cohort and 2 case-control studies, with 1,656 (46.3%) patients and 2,236 (48.5%) flaps having undergone prior surgery. Meta-analysis showed patients with prior abdominal surgery were significantly more likely to experience donor-site delayed wound healing with a risk ratio of 1.27 (random 95% CI [1.00; 1.61]; = 4) after adjustment for publication bias. No other complications were statistically different between groups.

Conclusion:  In patients with a history of prior abdominal surgery, abdominally based free tissue transfer is a safe and reliable option. Abdominal scars may slightly increase the risk of delayed donor-site wound healing, which can aid the surgeon in preoperative counseling.
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http://dx.doi.org/10.1055/s-0041-1723816DOI Listing
March 2021

Breast Cancer Extirpation, Reconstruction, and COVID-19: Paradigm Shifting Management during a Global Pandemic.

Plast Reconstr Surg Glob Open 2021 Jan 31;9(1):e3396. Epub 2020 Dec 31.

Division of Plastic Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wis.

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http://dx.doi.org/10.1097/GOX.0000000000003396DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7861651PMC
January 2021

Risks of Free Tissue Transfer in the Hypocoaguable Patient.

J Reconstr Microsurg 2020 Mar 6;36(3):e5. Epub 2021 Feb 6.

Division of Plastic Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.

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http://dx.doi.org/10.1055/s-0041-1723818DOI Listing
March 2020

Beyond the Core Suture: A New Approach to Tendon Repair.

Plast Reconstr Surg Glob Open 2020 Dec 17;8(12):e3280. Epub 2020 Dec 17.

Division of Plastic and Reconstructive Surgery, Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wis.

Despite significant improvements in zone II flexor tendon repair over the last 2 decades, function-limiting complications persist. This article describes 2 novel repair techniques utilizing flexor digitorum superficialis (FDS) autografts to buttress the flexor digitorum profundus (FDP) repair site without the use of core sutures. The hypothesis being that the reclaimed FDS tendon autograft will redistribute tensile forces away from the FDP repair site, increasing overall strength and resistance to gapping in Zone II flexor tendon injuries compared with the current clinical techniques.

Methods: Two novel FDP repair methods utilizing portions of FDS have been described: (1) asymmetric repair (AR), and (2) circumferential repair. Ultimate tensile strength and cyclical testing were used to compare novel techniques to current clinical standard repairs: 2-strand (2-St), 4-strand (4-St), and 6-strand (6-St) methods. All repairs were performed in cadaveric sheep tendons (n = 10/group), by a single surgeon.

Results: AR and circumferential repair techniques demonstrated comparable ultimate tensile strength to 6-St repairs, with all 3 of these techniques able to tolerate significantly stronger loads than the 2-St and 4-St repairs ( 0.0001). Cyclical testing demonstrated that AR and circumferential repair were able to withstand a significantly higher total cumulative force ( 0.001 and = 0.0064, respectively) than the 6-St, while only AR tolerated a significantly greater force to 2-mm gap formation ( = 0.042) than the 6-St repair.

Conclusion: Incorporating FDS as an autologous graft for FDP repair provides at least a comparable ultimate tensile strength and a significantly greater cumulative force to failure and 2-mm gap formation than a traditional 6-St repair.
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http://dx.doi.org/10.1097/GOX.0000000000003280DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7787298PMC
December 2020

Augmentation of Chicken Thigh Model with Fluorescence Imaging Allows for Real-Time, High Fidelity Assessment in Supermicrosurgery Training.

J Reconstr Microsurg 2020 Dec 30. Epub 2020 Dec 30.

Division of Plastic Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.

Background:  The skills required for supermicrosurgery are hard-earned and difficult to master. The University of Wisconsin "blue-blood" chicken thigh model incorporates perfusion of the thigh vessels with a blue liquid solution, allowing users to visualize flow across their anastomoses. This model has proven to be an excellent source of small vessels (down to 0.3 mm) but assessing the quality of anastomoses at this spatial scale has proven difficult. We evaluated whether fluorescent imaging with indocyanine green (ICG) in this realistic training model would enhance the assessment of supermicrosurgical anastomoses, and therefore improve real-time feedback to trainees.

Methods:  Anastomoses of vessels ranging from 0.35 to 0.55mm in diameter were performed followed by the capture of white light with and without fluorescence imaging overlay during infusion of "blue-blood" and ICG. Videos were randomized and shown to seven fellowship-trained microsurgeons at the University of Wisconsin-Madison who rated each anastomosis as "patent," "not patent," or "unsure." Surgeon accuracy, uncertainty, and inter-rater agreement were measured for each imaging modality.

Results:  Use of fluorescence significantly increased surgeon accuracy to 91% compared with 47% with white light alone ( = 0.015), decreased surgeon uncertainty to 4% compared with 41% with white light alone ( = 0.011), and improved inter-rater agreement from 53.1% with white light alone to 91.8% ( = 0.016).

Conclusion:  Augmentation of the University of Wisconsin "blue-blood" chicken thigh model with ICG fluorescence improves accuracy, decreases uncertainty, and improves inter-rater agreement when assessing supermicrosurgical anastomoses in a training setting. This improved, real-time feedback enhances this model's value as a supermicrosurgical training tool.
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http://dx.doi.org/10.1055/s-0040-1722184DOI Listing
December 2020

The Blue-Blood Porcine Chest Wall: A Novel Microsurgery Training Simulator for Internal Mammary Vessel Dissection and Anastomosis.

J Reconstr Microsurg 2020 Sep 21. Epub 2020 Sep 21.

Division of Plastic Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.

Background:  Preparation of the internal mammary artery (IMA) is a critical step in autologous breast reconstruction. Intraoperatively, there is limited opportunity for residents to practice this skill. Porcine models provide highly realistic simulation for vascular surgery; however, use of live laboratory pigs is expensive, inconvenient, and offers limited opportunity for repetitive training. We aimed to develop an inexpensive and effective training model for IMA preparation. This article describes creation of a novel microsurgical model using cadaveric chest walls of Wisconsin Miniature Swine embedded in a modified mannequin thorax and augmented with a blue-blood perfusion system.

Methods:  Anatomic comparison: five porcine chest walls were dissected, and various anatomic measurements were made for anatomic comparison to existing human data in the literature. Model assembly: the chest wall is prepared by cannulating the proximal and distal ends of the internal mammary vessels with angiocatheters, which are then connected to the blue-blood perfusion system. The model is assembled in four layers including: (1) a mannequin thorax with a window removed to expose the first to fourth intercostal spaces, bilaterally, (2) a layer of foam simulating fat, (3) the perfused pig chest wall, and (4) a second mannequin shell placed posteriorly for support.

Results:  The porcine chest walls are similar to humans with regards to vessel size and location. This model can be assembled quickly, with a one-time approximate cost of $55.00, and allows for six training sessions per specimen. The model allows residents to practice the key steps of IMA preparation including dissection, elevation of perichondria, and vascular anastomosis while working at a depth that closely simulates the human thorax. Continuous blue-blood perfusion provides immediate feedback on anastomosis quality.

Conclusion:  Overall, this novel model can provide inexpensive and realistic simulation of internal mammary vessel preparation and anastomosis.
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http://dx.doi.org/10.1055/s-0040-1716859DOI Listing
September 2020

Utility of health services regions in examining socioeconomic disparities in receipt of breast reconstruction.

Breast J 2020 09 1;26(9):1895-1897. Epub 2020 Jul 1.

Department of Surgery, Wisconsin Surgical Outcomes Research Program, University of Wisconsin, Madison, Wisconsin, USA.

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http://dx.doi.org/10.1111/tbj.13959DOI Listing
September 2020

The Effect of Perforator Skeletonization on Pedicled Fasciocutaneous Flaps of the Lower Extremity: A Systematic Review.

J Reconstr Microsurg 2020 Nov 24;36(9):634-644. Epub 2020 Jun 24.

Division of Plastic Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.

Background:  Lower extremity defects often require free tissue transfer due to a paucity of local donor sites. Locoregional perforator-based flaps offer durable, single-stage reconstruction while avoiding the pitfalls of microsurgery. Multiple harvest techniques are described, yet few studies provide outcome comparisons. Specifically, no study has examined the impact of perforator flap pedicle skeletonization on reconstructive outcomes. This systematic review characterizes technique and impact of pedicle skeletonization on perforator-based fasciocutaneous flaps of the lower extremity.

Methods:  PubMed, Scopus, and the Cochrane Central Register of Controlled Trials were reviewed for literature examining perforator-based fasciocutaneous flaps from knee to ankle, from January 2000 through November 2018. The Preferred Reporting Items for Systematic Reviews-Individual Participant Data (PRISMA-IPD) structure was used.

Results:  Thirty-six articles were included for quantitative analysis. Of 586 flaps, 365 were skeletonized (60.1%) with 58 major (9.9%) and 19 minor complications (3.2%). With skeletonization, overall reoperative rate was higher (odds ratio [OR]: 9.71,  = 0.004), specifically in propeller (OR: 12.50,  = 0.004) and rotational flaps (OR: 18.87,  = 0.004). The complication rate of rotational flaps also increased (OR: 2.60,  = 0.04). Notably, skeletonization reduced complications in flaps rotated 90 degrees or more (OR: 0.21,  = 0.02). Reoperative rate of distal third defects (OR: 14.08,  = 0.02), flaps over 48 cm (OR: 33.33,  = 0.01), and length to width ratios over 1.75 (OR: 7.52,  = 0.03) was increased with skeletonization. Skeletonization increased complications in traumatic defects (OR: 2.87,  = 0.04) and reduced complications in malignant defects (OR: 0.10,  = 0.01).

Conclusion:  Pedicled, perforator-based flaps can provide a reliable locoregional alternative to free tissue transfer for lower extremity defects. Though skeletonization increased the overall reoperative rate, the complication rate for flaps with 90 degrees or more of rotation was significantly reduced. This suggests skeletonization should be considered when large rotational movements are anticipated to reduce complications that can arise from pedicle compression and venous congestion.
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http://dx.doi.org/10.1055/s-0040-1713598DOI Listing
November 2020

Resident Perspectives on Effective Surgical Training: Incivility, Confidence, and Mindset.

J Surg Educ 2020 Sep - Oct;77(5):1088-1096. Epub 2020 Jun 13.

Division of Plastic and Reconstructive Surgery, Department of Surgery, University of Wisconsin - Madison, Madison, Wisconsin. Electronic address:

Objective: Ample evidence exists that one's internal state (e.g., mindset, emotion) impacts one's performance. Both the military and sports organizations have focused on optimizing internal states of their service members and athletes, respectively, to improve performance and wellbeing. The internal states of surgical residents and the factors that influence their internal states have not yet been examined. Our goal is to better understand whether certain internal states are beneficial for resident operative performance, and how to optimize these during surgical training.

Design: A 17-question survey, containing both open-ended and multiple-choice questions, was distributed to all (n = 134) surgical residents at the University of Wisconsin. In open-ended questions, recurring themes were identified utilizing content analysis. Recurring themes stated by 25% or more of the respondents are reported.

Setting: Department of Surgery at the University of Wisconsin-Madison.

Participants: Surgical residents at the University of Wisconsin.

Results: The survey response rate varied between n = 47 (35%) and n = 32 (24%), as not all respondents answered all questions. (1) Effective surgical educators were identified to demonstrate humanism and focus on teaching. (2) Nearly all residents affirmed that certain mindsets help them excel in the OR, including positive and confident mindsets. (3) Nearly all residents affirmed that faculty and senior residents influence their mindsets. (4) Constructive resident mindsets were promoted by positive faculty behaviors and personal preparation, while negative faculty behaviors were identified to stifle constructive mindsets. (5) Factors contributing to favorable OR performance included personal preparation and positive OR environments. (6) Factors contributing to poor OR performance included inadequate preparation and negative interactions with faculty.

Conclusions: Residents near unanimously believe that certain mindsets help them excel, and that faculty impact their mindsets. As teachers, we must strive to better understand how to foster constructive mindsets in residents to optimize learning, performance, and wellbeing.
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http://dx.doi.org/10.1016/j.jsurg.2020.04.002DOI Listing
June 2020

Slowing the Spread and Minimizing the Impact of COVID-19: Lessons from the Past and Recommendations for the Plastic Surgeon.

Plast Reconstr Surg 2020 09;146(3):681-689

From the Department of Surgery, Division of Plastic Surgery, University of Wisconsin School of Medicine and Public Health.

Background: Coronavirus disease 2019 (COVID-19), a novel coronavirus originating in December of 2019 in Wuhan, People's Republic of China, has spread rapidly throughout the globe over 3 months. On March 11, 2020, the World Health Organization declared COVID-19 a global pandemic. COVID-19 represents a nearly unprecedented threat to both the public health and the durability of our health care systems and will profoundly affect the field of plastic and reconstructive surgery. The objective of this article is to provide a natural history of COVID-19-including virology, epidemiology, and transmission patterns-and a guide for plastic surgeons regarding patient and resource management.

Methods: The authors reviewed existing literature regarding COVID-19, both primary research and secondary reviews, by means of PubMed queries, and recommendations from relevant professional organizations (e.g., American College of Surgeons and American Society of Plastic Surgeons). The literature and recommendations were summarized to provide a specific guide for plastic surgeons.

Results: Internationally, over 5.7 million cases and 357,000 deaths from COVID-19 have been reported at the time of writing. No pharmacologic treatments have been identified, but epidemiologic strategies were identified to prevent viral spread, preserve health care resources, and protect patients and surgeons globally. Specific recommendations for plastic and reconstructive surgeons include postponing elective cases and transitioning to telecommunication platforms for patient consultations and education.

Conclusions: COVID-19 represents a nearly unprecedented threat to the public health and the durability of health care systems in the contemporary era. Although plastic and reconstructive surgery may seem relatively remote from the pandemic in direct patient care and exposure, our field can significantly enhance health care resource management.
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http://dx.doi.org/10.1097/PRS.0000000000007221DOI Listing
September 2020

Clinically-derived vagus nerve stimulation enhances cerebrospinal fluid penetrance.

Brain Stimul 2020 Jul - Aug;13(4):1024-1030. Epub 2020 Mar 26.

Department of Biomedical Engineering, University of Wisconsin-Madison, 1550 Engineering Drive, Madison, WI, 53706, USA; Department of Neurological Surgery, School of Medicine and Public Health, University of Wisconsin Madison, Madison, WI, 53706, USA. Electronic address:

Introduction: Vagus nerve stimulation (VNS) is an FDA-approved neuromodulatory treatment used in the clinic today for epilepsy, depression, and cluster headaches. Moreover, evidence in the literature has led to a growing list of possible clinical indications, with several small clinical trials applying VNS to treat conditions ranging from neurodegenerative diseases to arthritis, anxiety disorders, and obesity. Despite the growing list of therapeutic applications, the fundamental mechanisms by which VNS achieves its beneficial effects are poorly understood. In parallel, the glymphatic and meningeal lymphatic systems have recently been described as methods by which the brain maintains a healthy homeostasis and removes waste without a traditionally defined lymphatic system. In particular, the glymphatic system relates to the interchange of cerebrospinal fluid (CSF) and interstitial fluid (ISF) whose net effect is to wash through the brain parenchyma removing metabolic waste products and misfolded proteins.

Objective/hypothesis: As VNS has well-documented effects on many of the pathways recently linked to the clearance systems of the brain, we hypothesized that VNS could increase CSF penetrance in the brain.

Methods: We injected a low molecular weight lysine-fixable fluorescent tracer (TxRed-3kD) into the CSF system of mice with a cervical vagus nerve cuff implant and measured the amount of CSF penetrance following an application of a clinically-derived VNS paradigm (30 Hz, 10% duty cycle).

Results: We found that the clinical VNS group showed a significant increase in CSF tracer penetrance as compared to the naïve control and sham groups.

Conclusion: (s): This study demonstrates that VNS therapeutic strategies already being applied in the clinic today may induce intended effects and/or unwanted side effects by altering CSF/ISF exchange in the brain. This may have broad ranging implications in the treatment of various CNS pathologies.
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http://dx.doi.org/10.1016/j.brs.2020.03.012DOI Listing
December 2020

Recovery and Regrowth After Nerve Repair: A Systematic Analysis of Four Repair Techniques.

J Surg Res 2020 07 19;251:311-320. Epub 2020 Mar 19.

Division of Plastic Surgery, Department of Surgery, University of Wisconsin, Madison, Wisconsin; Department of Biomedical Engineering, College of Engineering, University of Wisconsin, Madison, Wisconsin. Electronic address:

Background: Outcome assessments that evaluate post-transection nerve repair do not often correlate with one another. The aims of this study were twofold: to compare four nerve repair techniques with each other and incorporate both negative and positive control groups and to identify possible correlations between outcome assessments.

Materials And Methods: Sciatic nerve transection and repair was performed in Lewis rats using one of the following techniques: interrupted epineural, running epineural, grouped fascicular, epineural with absorbable type I collagen wrap, and high tension for incorporation of a negative control. A sham surgery group was also included as a positive control group. Outcomes were compared using assessments of functional recovery (behavior and electrophysiology) and nerve regrowth (imaging and histomorphometry). Three-dimensional printed custom electrode stabilization and imaging devices were designed and fabricated to provide standardization in assessment between subjects.

Results: Nerve repair was performed in 48 male Lewis rats. In all animals, functional testing was performed at week 13. The sham group (n = 7) performed the best on both behavioral assays (P < 0.001) and electrophysiology assessments (P < 0.001). The negative control group (high tension) performed poorest on multiple assessments, and there were no significant differences observed for any of the four repair types. Positive correlations were observed between behavioral and histomorphometric tests.

Conclusions: There was no difference in outcome between the four types of nerve repair. High-tension nerve repair represents an ideal negative control. Not all assessment methods correlate equally, and consistent use of complimentary outcome assessments could allow for improved comparison between studies.
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http://dx.doi.org/10.1016/j.jss.2020.01.012DOI Listing
July 2020

Functional vagotopy in the cervical vagus nerve of the domestic pig: implications for the study of vagus nerve stimulation.

J Neural Eng 2020 04 9;17(2):026022. Epub 2020 Apr 9.

Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States of America. Mayo Clinic, Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN, United States of America.

Objective: Given current clinical interest in vagus nerve stimulation (VNS), there are surprisingly few studies characterizing the anatomy of the vagus nerve in large animal models as it pertains to on-and off-target engagement of local fibers. We sought to address this gap by evaluating vagal anatomy in the pig, whose vagus nerve organization and size approximates the human vagus nerve.

Approach: Here we combined microdissection, histology, and immunohistochemistry to provide data on key features across the cervical vagus nerve in a swine model, and compare our results to other animal models (mouse, rat, dog, non-human primate) and humans.

Main Results: In a swine model we quantified the nerve diameter, number and diameter of fascicles, and distance of fascicles from the epineural surface where stimulating electrodes are placed. We also characterized the relative locations of the superior and recurrent laryngeal branches of the vagus nerve that have been implicated in therapy limiting side effects with common electrode placement. We identified key variants across the cohort that may be important for VNS with respect to changing sympathetic/parasympathetic tone, such as cross-connections to the sympathetic trunk. We discovered that cell bodies of pseudo-unipolar cells aggregate together to form a very distinct grouping within the nodose ganglion. This distinct grouping gives rise to a larger number of smaller fascicles as one moves caudally down the vagus nerve. This often leads to a distinct bimodal organization, or 'vagotopy'. This vagotopy was supported by immunohistochemistry where approximately half of the fascicles were immunoreactive for choline acetyltransferase, and reactive fascicles were generally grouped in one half of the nerve.

Significance: The vagotopy observed via histology may be advantageous to exploit in design of electrodes/stimulation paradigms. We also placed our data in context of historic and recent histology spanning multiple models, thus providing a comprehensive resource to understand similarities and differences across species.
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http://dx.doi.org/10.1088/1741-2552/ab7ad4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7306215PMC
April 2020

Experimental Basis for Creating an Osseointegrated Neural Interface for Prosthetic Control: A Pilot Study in Rabbits.

Mil Med 2020 01;185(Suppl 1):462-469

Division of Plastic Surgery, Department of Surgery, University of Wisconsin-Madison, 600 Highland Avenue, Madison WI 53792.

Introduction: While debate persists over how to best prevent or treat amputation neuromas, the more pressing question of how to best marry residual nerves to state-of-the-art robotic prostheses for naturalistic control of a replacement limb has come to the fore. One potential solution involves the transposition of terminal nerve ends into the medullary canal of long bones, creating the neural interface within the bone. Nerve transposition into bone is a long-practiced, clinically relevant treatment for painful neuromas. Despite neuropathic pain relief, the physiological capacity of transposed nerves to conduct motor and sensory signals required for prosthesis control remains unknown. This pilot study addresses the hypotheses that (1) bone provides stability to transposed nerves and (2) nerves transposed into bone remain physiologically active, as they relate to the creation of an osseointegrated neural interface.

Methods: New Zealand white rabbits received transfemoral amputation, with the sciatic nerve transposed into the femur.

Results: Morphological examination demonstrates that nerves remain stable within the medullary canal, while compound nerve action potentials evoked by electrical stimulation of the residual nerve within the bone could be achieved at 12 weeks (p < 0.0005).

Conclusion: Transposed nerves retain a degree of physiological function suitable for creating an osseointegrated neural interface.
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http://dx.doi.org/10.1093/milmed/usz246DOI Listing
January 2020

Cuff and sieve electrode (CASE): The combination of neural electrodes for bi-directional peripheral nerve interfacing.

J Neurosci Methods 2020 04 22;336:108602. Epub 2020 Jan 22.

Department of Electrical and Computer Engineering, United States. Electronic address:

Background: A number of peripheral nerve interfaces for nerve stimulation and recording exist for the purpose of controlling neural prostheses, each with a set of advantages and disadvantages. The ultimate goal of neural prostheses is a seamless bi-directional communication between the peripheral nervous system and the prosthesis. Here, we developed an interfacing electrode array, the "cuff and sieve electrodes" (CASE), integrating microfabricated cuff and sieve electrodes to a single unit, to decrease the weaknesses faced by these electrode designs in isolation. This paper presents the design and fabrication of CASE with ex vivo and in vivo testing towards chronic application.

Methods: Electroplating on electrode sites was performed to improve electrical properties of CASE. The surface morphology and chemical compound were characterized using scanning electron microscopy and energy-dispersive spectroscopy, respectively. Electrochemical impedance spectroscopy and cyclic voltammetry were performed to evaluate the electrical properties of CASE and determine viability for in vivo applications. Terminal CASE implantations were performed in a rat sciatic transection model to test the ease of implantation and capacity to write sensory information into the biological system.

Results: The modified platinum film resulted in reducing impedance magnitude (9.18 kΩ and 2.27 kΩ) and increasing phase angle (over 70°). CASE stimulation of the sciatic nerve at different amplitudes elicited significantly different cortical responses (p < 0.005) as demonstrated by somatosensory evoked potentials, recorded via micro-electrocorticography.

Conclusions: The ability to elicit cortical responses from sciatic nerve stimulation demonstrates the proof of concept for both the implantation and chronic monitoring of CASE interfaces for innovative prosthetic control.
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http://dx.doi.org/10.1016/j.jneumeth.2020.108602DOI Listing
April 2020

The Classification and Surgical Treatment of Adult Acquired Buried Penis Syndrome: A Call for Data and Collaboration.

Authors:
Samuel O Poore

Aesthet Surg J 2020 01;40(2):NP83-NP84

Division of Plastic Surgery, Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, WI.

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http://dx.doi.org/10.1093/asj/sjz300DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6988514PMC
January 2020

Methodology for creating a chronic osseointegrated neural interface for prosthetic control in rabbits.

J Neurosci Methods 2020 02 8;331:108504. Epub 2019 Nov 8.

Division of Plastic Surgery, Department of Surgery, University of Wisconsin - Madison, Madison, WI, United States; Department of Biomedical Engineering, College of Engineering, University of Wisconsin - Madison, Madison, WI, United States. Electronic address:

Background: Chronic stability and high degrees of selectivity are both essential but somewhat juxtaposed components for creating an implantable bi-directional PNI capable of controlling of a prosthetic limb. While the more invasive implantable electrode arrays provide greater specificity, they are less stable over time due to compliance mismatch with the dynamic soft tissue environment in which the interface is created.

New Method: This paper takes the surgical approach of transposing nerves into bone to create neural interface within the medullary canal of long bones, an osseointegrated neural interface, to provide greater stability for implantable electrodes. In this context, we describe the surgical model for transfemoral amputation with transposition of the sciatic nerve into the medullary canal in rabbits. We investigate the capacity to create a neural interface within the medullary canal histolomorphologically. In a separate proof of concept experiment, we quantify the chronic physiological capacity of transposed nerves to conduct compound nerve action potentials evoked via an Osseointegrated Neural Interface.

Comparison With Existing Method(s): The rabbit serves as an important animal model for both amputation neuroma and osseointegration research, but is underutilized for the exploration neural interfacing in an amputation setting.

Results: Our findings demonstrate that transposed nerves remain stable over 12 weeks. Creating a neural interface within the medullary canal is possible and does not impede nerve regeneration or physiological capacity.

Conclusions: This article represents the first evidence that an Osseointegrated Neural Interface can be surgically created, capable of chronic stimulation/recording from amputated nerves required for future prosthetic control.
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http://dx.doi.org/10.1016/j.jneumeth.2019.108504DOI Listing
February 2020

Multispecialty Microsurgical Course Utilizing the Blue-Blood Chicken Thigh Model Significantly Improves Resident Comfort, Confidence, and Attitudes in Multiple Domains.

J Reconstr Microsurg 2020 Feb 5;36(2):142-150. Epub 2019 Nov 5.

Division of Plastic Surgery, Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.

Background:  The high level of technical skill required by microsurgical procedures has prompted the development of in vitro educational models. Current models are cost-ineffective, unrealistic, or carry ethical implications and are utilized as isolated experiences within single surgical specialties. The purpose of this study was to assess the educational and interprofessional effect of a microsurgical training course utilizing the nonliving "Blue-Blood" chicken thigh model (BBCTM) in a multidisciplinary environment.

Methods:  A 10-hour course was developed integrating didactic lectures, case presentations, and one-on-one practical sessions utilizing hydrogel microvessels and the BBCTM. Pre- and postcourse surveys were administered assessing participants' self-reported comfort and confidence within fundamental microsurgical domains, assessments of the models utilized, and the effects of a multidisciplinary environment on the experience.

Results:  A total of 19 residents attended the course on two separate occasions ( = 10 and  = 9, respectively). Respondents varied from postgraduate year-2 (PGY-2) to PGY-6+ and represented plastic and reconstructive surgery ( = 10), urology ( = 6), and otolaryngology ( = 3). On average, each participant performed 4.3 end-to-end, 1.3 end-to-side, and 0.4 coupler-assisted anastomoses. Following the course, participants felt significantly more comfortable operating a microscope and handling microsurgical instruments. They felt significantly more confident handling tissues, manipulating needles, microdissecting, performing end-to-end anastomoses, performing end-to-side anastomoses, using an anastomotic coupler, and declaring anastomoses suitable (all  < 0.05). The majority of participants believed that the use of live animals in the course would have minimally improved their learning. All but two respondents believed the course improved their awareness of the value of microsurgery in other specialties "very much" or "incredibly."

Conclusion:  A microsurgical training course utilizing nonliving models such as the "BBCTM significantly improves resident comfort and confidence in core operative domains and offers an in vivo experience without the use of live animals. Multispecialty training experiences in microsurgery are beneficial, desired, and likely underutilized.
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http://dx.doi.org/10.1055/s-0039-1700523DOI Listing
February 2020

Enhanced Recovery after Surgery in Breast Reconstruction: A Systematic Review.

J Reconstr Microsurg 2019 Nov 1;35(9):695-704. Epub 2019 Aug 1.

Division of Plastic and Reconstructive Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.

Background:  Enhanced Recovery after Surgery (ERAS) principles have received focused attention in breast reconstruction. Many protocols have been described in the literature for both autologous and alloplastic reconstruction. This systematic review serves to better characterize successful ERAS protocols described in the literature for potential ease of adoption at institutions desiring implementation.

Methods:  A systematic review of ERAS protocols for autologous and alloplastic breast reconstruction was conducted using Medline, the Cochrane Database, and Web of Science.

Results:  Eleven cohort studies evaluating ERAS protocols for autologous ( = 8) and alloplastic ( = 3) breast reconstruction were included for review. The majority compared with a retrospective cohort of traditional perioperative care. All studies described the full spectrum of implemented ERAS protocols including preoperative, intraoperative, and postoperative phases of care. Most frequently reported significant outcomes were reduced length of stay and opioid use with ERAS implementation. No significant change in major complication or readmission rate was demonstrated.

Conclusion:  Based on this systematic review, several core elements that make up a successful perioperative enhanced recovery protocol for breast reconstruction have been identified. Elements include patient counseling and education, limited preoperative fasting, appropriate thromboprophylaxis and antibiotic prophylaxis dependent on reconstructive method, preoperative antiemetics, multimodal analgesia and use of local anesthetic, goal-directed intravenous fluid management, prompt removal of drains and catheters, early diet advancement, and encouragement of ambulation postoperatively. Implementation of ERAS protocols in both autologous and alloplastic breast reconstruction can positively enhance patient experience and improve outcomes by reducing length of stay and opioid use, without compromising successful reconstructive outcomes.
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http://dx.doi.org/10.1055/s-0039-1693699DOI Listing
November 2019

Major Histocompatibility Complex-Matched Arteries Have Similar Patency to Autologous Arteries in a Mauritian Cynomolgus Macaque Major Histocompatibility Complex-Defined Transplant Model.

J Am Heart Assoc 2019 08 17;8(15):e012135. Epub 2019 Jul 17.

Department of Surgery Division of Plastic Surgery School of Medicine and Public Health University of Wisconsin Madison WI.

Background Arterial bypass and interposition grafts are used routinely across multiple surgical subspecialties. Current options include both autologous and synthetic materials; however, each graft presents specific limitations. Engineering artificial small-diameter arteries with vascular cells derived from induced pluripotent stem cells could provide a useful therapeutic solution. Banking induced pluripotent stem cells from rare individuals who are homozygous for human leukocyte antigen alleles has been proposed as a strategy to facilitate economy of scale while reducing the potential for rejection of induced pluripotent stem cell-derived transplanted tissues. Currently, there is no standardized model to study transplantation of small-diameter arteries in major histocompatibility complex-defined backgrounds. Methods and Results In this study, we developed a limb-sparing nonhuman primate model to study arterial allotransplantation in the absence of immunosuppression. Our model was used to compare degrees of major histocompatibility complex matching between arterial grafts and recipient animals with long-term maintenance of patency and function. Unexpectedly, we (1) found that major histocompatibility complex partial haplomatched allografts perform as well as autologous control grafts; (2) detected little long-term immune response in even completely major histocompatibility complex mismatched allografts; and (3) observed that arterial grafts become almost completely replaced over time with recipient cells. Conclusions Given these findings, induced pluripotent stem cell-derived tissue-engineered blood vessels may prove to be promising and customizable grafts for future use by cardiac, vascular, and plastic surgeons.
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http://dx.doi.org/10.1161/JAHA.119.012135DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6761673PMC
August 2019

Strategies for interfacing with the trigeminal nerves in rodents for bioelectric medicine.

J Neurosci Methods 2019 08 20;324:108321. Epub 2019 Jun 20.

Department of Biomedical Engineering, University of Wisconsin-Madison, United States; Department of Neurological Surgery, University of Wisconsin-Madison, United States. Electronic address:

Background: Bioelectric medicine seeks to modulate neural activity via targeted electrical stimulation to treat disease. Recent clinical evidence supports trigeminal nerve stimulation as a bioelectric treatment for several neurological disorders; however, the mechanisms of trigeminal nerve stimulation and potential side effects remain largely unknown. The goal of this study is to optimize the methodology and reproducibility of neural interface implantation for mechanistic studies in rodents.

New Method(s): This article describes a single incision surgical approach to the infraorbital nerve of rats and mice and the supraorbital nerve in rats for trigeminal nerve stimulation studies. This article also presents the use of cortical evoked potentials and electromyography as methods for demonstrating effective engagement between the implanted electrode and target nerve.

Comparison With Existing Method(s): A number of surgical approaches to the infraorbital nerve in rats exist, many of which are technically difficult. A simple, standardized approach to infraorbital nerve in rats and mice, as well as the supraorbital nerve of rats is integral to reproducibility of future trigeminal nerve stimulation studies.

Conclusion: The infraorbital nerve of rats and mice can be easily accessed from a single dorsal incision on the bridge of the nose that avoids major anatomical structures such as the facial nerve. The supraorbital nerve is also accessible in rats from a single dorsal incision, but not mice due to size. Successful interfacing and engagement of the infra- and supraorbital nerves using the described methodology is demonstrated by recording of evoked cortical potentials and electromyography.
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http://dx.doi.org/10.1016/j.jneumeth.2019.108321DOI Listing
August 2019

Divulge the bulge: an international survey of abdominal donor site morbidity in free autologous breast reconstruction.

J Plast Surg Hand Surg 2019 Oct 23;53(5):265-270. Epub 2019 Apr 23.

Division of Plastic and Reconstructive Surgery, University of Wisconsin School of Medicine and Public Health , Madison , WI , USA.

The frequency of donor-site complications following abdominal free-flap breast reconstruction remains controversial. Consensus on strategies to minimize morbidity is underdeveloped. An online survey was distributed to surgeons practicing free-flap breast reconstruction worldwide. Contact information was obtained (1) official website listings/directories of US Plastic Surgery residencies/fellowships and (2) first/last authors of PubMed-indexed publications relating to free autologous breast reconstruction over the past decade. Questions related to practice environment, surgical volume/preferences, complications, mesh-use, referrals and perceptions of interventions for decreasing abdominal complications. Statistics were performed using non-parametric Kruskal-Wallis H test. The response rate was 26% (140/537). The majority of respondents came from the United States (100, 71%), and reported an academic practice environment (120, 86%). Fifty-six percent reported bulge rates ≥3% and sixteen percent reported bulge rates ≥10%. Most (93%) reported 0-2% hernia incidence. Those performing fewer surgeries were more likely to use mesh (=.034) and report higher bulge incidence (=.002). US surgeons performed a lower fraction of deep inferior epigastric perforator (DIEP) flaps (<.001) and were more likely to believe that mesh use lowered complication risk (<.001). Bulge and hernia incidence were associated with an increased proportion of non-DIEPs performed and mesh use (=.004 and =.024). Most respondents (54%) 'never' or 'rarely' had patients see occupations/physical therapy postoperatively. Bulge and abdominal muscle weakness are under-recognized donor site complications following free-flap breast reconstruction. Low surgical volume, non-DIEP reconstruction and mesh use may be associated with higher complication rates. Current practice patterns to reduce morbidity vary widely both domestically and internationally.
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http://dx.doi.org/10.1080/2000656X.2019.1597372DOI Listing
October 2019

Psychological Theory as It Applies to Surgical Training.

Ann Surg 2019 05;269(5):812-814

Division of Plastic and Reconstructive Surgery, Department of Surgery, University of Wisconsin - Madison, Madison, WI.

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http://dx.doi.org/10.1097/SLA.0000000000003180DOI Listing
May 2019

Nuances of Postoperative Management of Microvascular Breast Reconstruction Patients: Where Are the Data?

Plast Reconstr Surg 2019 03;143(3):672e-673e

Division of Plastic and Reconstructive Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wis.

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http://dx.doi.org/10.1097/PRS.0000000000005355DOI Listing
March 2019

The Surgical Treatment of Adult Acquired Buried Penis Syndrome: A New Classification System.

Aesthet Surg J 2019 08;39(9):979-988

Departments of Surgery (Division of Plastic and Reconstructive Surgery) and Urology, University of Wisconsin School of Medicine and Public Health, Madison, WI.

Background: Adult acquired buried penis syndrome may be associated with an inability to void, sexual dysfunction, and recurrent infection. Previously published classification systems rely on intraoperative findings, such as penile skin quality.

Objectives: The purpose of this study was to evaluate outcomes after adult acquired buried penis repair and to develop a classification system based on preoperative assessment.

Methods: The authors reviewed data from patients who underwent buried penis reconstruction at a single institution. Patient history and physical examination guided the development of a classification system for surgical planning.

Results: Of the 27 patients included, the mean age was 56 ± 15 years and mean body mass index was 49 ± 14 kg/m2. Patients were classified into 4 groups based on examination findings: (I) buried penis due to skin deficiency, iatrogenic scarring, and/or diseased penile skin (n = 3); (II) excess abdominal skin and fat (n = 6); (III) excess skin and fat with diseased penile skin (n = 16); and (IV) type III plus severe scrotal edema (n = 2). Surgical treatment (eg, excision and grafting, mons suspension, panniculectomy, translocation of testes, and/or scrotectomy) was tailored based on classification. Complications included wound breakdown (n = 3), cellulitis (n = 4), and hematoma (n = 1). Nearly all patients (96%) reported early satisfaction and improvement in their symptoms postoperatively.

Conclusions: Classifying patients with buried penis according to preoperative examination findings may guide surgical decision-making and preoperative counseling and allow for optimized aesthetics to enhance self-esteem and sexual well-being.

Level Of Evidence: 4:
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http://dx.doi.org/10.1093/asj/sjy325DOI Listing
August 2019

Characterizing cortical responses evoked by electrical stimulation of the mouse infraorbital nerve.

Annu Int Conf IEEE Eng Med Biol Soc 2018 Jul;2018:4756-4759

In recent years, the trigeminal nerve (CN V) has become a popular target for neuromodulation therapies to treat of a variety of diseases due to its access to neuromodulatory centers. Despite promising preclinical and clinical data, the mechanism of action of trigeminal nerve stimulation (TNS) remains in question. In this work, we describe the development and evaluation of a neural interface targeting the mouse trigeminal nerve with the goal of enabling future mechanistic research on TNS. We performed experiments designed to evaluate the ability of a peripheral nerve interface (i.e. cuff electrode) to stimulate the infraorbital branch of the trigeminal nerve. We found that both artificial and naturalistic stimulation of the trigeminal nerve elicited robust cortical responses in the somatosensory cortex that scaled with increases in stimulus amplitude. These results suggest that an infraorbital nerve interface is a suitable candidate for examining the neural mechanisms of TNS in the mouse.
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http://dx.doi.org/10.1109/EMBC.2018.8513175DOI Listing
July 2018

Precise One-Suture Needle-Guided Technique for Window Creation in Supermicrosurgical End-to-Side Anastomosis.

J Reconstr Microsurg 2018 May 18;34(4):e1-e2. Epub 2018 Aug 18.

Division of Plastic and Reconstructive Surgery, Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.

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http://dx.doi.org/10.1055/s-0038-1667361DOI Listing
May 2018