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Introduction This research aims to validate the proficiency and accuracy of the robotic microsurgery platform using rat femoral vessel model. Materials and Methods Total of 256 rat femoral vessels were performed, half using robotic and the other by manual microanastomosis by 8 microsurgeons with less than 5 years of experience given 8 trials (rats) each. Vessel demographics, proficiency (duration of suture and Structured Assessment of Robotic Microsurgical Skills (SARMS)) and accuracy (patency and Scanning Electron Microscopic (SEM)) was analyzed between the two groups. Results Using the robot, an average of 4 trials was needed to reach a plateau in total anastomosis time and patency. Significant more time was required for each vessel anastomosis (34.33 versus 21.63 minutes on the 8th trial, p<0.001) one factor being higher number of sutures compared to the hand-sewn group (artery: 7.86±0.51 versus 5.86±0.67, p=0.035, vein: 12.63±0.49 versus 9.57±0.99, p=0.055). The SARMS scores became nonsignificant between the two group on the 4th trial. The SEM showed higher tendency of unevenly spaced sutures, infolding, tears in the vessel wall for the hand-sewn group. Conclusion Using the robot, similar patency, accuracy, and proficiency can be reached through fast but steep learning process within 4 trials (anastomosis of 8 vessels) as the hand-sewn group. The robotic anastomosis may take longer time, but this is due to the increased number of sutures reflecting higher precision and accuracy. Further insight of precision and accuracy was found through the SEM demonstrating the possibility of the robot to prevent unexpected and unwanted complications., Competing Interests: This research was funded in part by MMI. Symani robotic platform and necessary robotic instrumentation was provided by MMI as part of the research funding agreement between MMI and Asan Medical Center. The senior author Joon Pio Hong is a consultant for MMI., (Thieme. All rights reserved.)

Background:  As the number of extremity amputations continues to rise, so does the demand for prosthetics. Emphasizing the importance of a nerve interface that effectively amplifies and transmits physiological signals through peripheral nerve surgery is crucial for achieving intuitive control. The regenerative peripheral nerve interface (RPNI) is recognized for its potential to provide this technical support. Through animal experiment, we aimed to confirm the actual occurrence of signal amplification., Methods:  Rats were divided into three experimental groups: control, common peroneal nerve transection, and RPNI. Nerve surgeries were performed for each group, and electromyography (EMG) and nerve conduction studies (NCS) were conducted at the initial surgery, as well as at 2, 4, and 8 weeks postoperatively., Results:  All implemented RPNIs exhibited viability and displayed adequate vascularity with the proper color. Clear differences in latency and amplitude were observed before and after 8 weeks of surgery in all groups ( p  < 0.05). Notably, the RPNI group demonstrated a significantly increased amplitude compared with the control group after 8 weeks ( p  = 0.031). Latency increased in all groups 8 weeks after surgery. The RPNI group exhibited relatively clear signs of denervation with abnormal spontaneous activities (ASAs) during EMG., Conclusion:  This study is one of few preclinical studies that demonstrate the electrophysiological effects of RPNI and validate the neural signals. It serves as a foundational step for future research in human-machine interaction and nerve interfaces., Competing Interests: None declared., (Thieme. All rights reserved.)

Background:  Lymph nodes may play a potential role in lymphedema surgery. Radiologic evaluation of nodes may reveal the status of pathologic conditions but with limited accuracy. This study is the first to evaluate the efficacy of ultrasound in detecting functioning nodes in lymphedema patients and presents a criterion for determining the functionality of the lymph nodes., Methods:  This retrospective study reviews 30 lower extremity lymphedema cases which were candidates for lymph node to vein anastomosis. Lymphoscintigraphy and magnetic resonant lymphangiography (MRL) imaging were compared with ultrasound features which were correlated to intraoperative indocyanine green (ICG) nodal uptake as an indication of functionality., Results:  Majority were International Society of Lymphology stage 2 late (50.0%) and stage 3 (26.7%). ICG positive uptake (functioning nodes) was noted in 22 (73.3%), while 8 patients (26.6%) had negative uptake (nonfunctioning). Ultrasound had significantly the highest specificity (100%) for identifying functional nodes followed by lymphoscintigraphy (55%) and MRL (36%; p  =  0.002 , p < 0.001 , respectively). This was associated with 100% positive predictive value compared against lymphoscintigraphy (44%) and MRL (36%; p < 0.001 for both ). The identified ultrasound imaging criteria for functioning lymph node were oval lymph node shape (Solbiati Index), morphology, vascularity pattern, and vascularity quantification., Conclusion:  The use of ultrasound in nodal evaluation was proven effective in different pathologic conditions and demonstrated the best prediction for functionality of the lymph node based on the new evaluation criteria., Competing Interests: None declared., (Thieme. All rights reserved.)

Background:  This study aimed to quantify the blood flow of free flaps and compare the blood flow of small vessel (<0.8 mm) and larger vessel (>0.8 mm) anastomosed free flaps., Methods:  This retrospective study included patients treated successfully with a perforator free flap in the lower extremity between June 2015 and March 2017. A color duplex ultrasound system measured the flow volume through the pedicle by analyzing the mean flow peak velocity, flow volume, and flow volume per 100 g of the flap., Results:  A total of 69 patients were enrolled in this study. There was no statistical difference in peak velocity between the small vessel anastomosed free flap (25.2 ± 5.6) and larger vessel anastomosed free flap (26.5 ± 5.4). Flow volume (6.8 ± 4.2 vs. 6.3 ± 3.6) and flow volume/100 g (3.6 ± 3.9 vs. 6.2 ± 6.9) also did not show significant differences., Conclusion:  Small vessel (<0.8 mm) free flaps showed similar flow velocity and flow volume to larger vessel (>0.8 mm) anastomosed free flaps. Blood flow to the small vessel anastomosed free flap was sufficient despite its small vessel size., Competing Interests: None declared., (Thieme. All rights reserved.)

Background:  Elevation in different layers achieving thin flaps are becoming relatively common practice for perforator flaps. Although postreconstruction debulking achieves pleasing aesthetic results and is widely practiced, customized approach during elevation to achieve the ideal thickness will increase efficiency while achieving the best possible aesthetic outcome. Multiple planes for elevation have been reported along with different techniques but it is quite confusing and may lack correspondence to the innate anatomy of the skin and subcutaneous tissue., Methods:  This article reviews the different planes of elevation and aims to clarify the definition and classification in accordance to anatomy and present the pros and cons of elevation based on the different layers and provide technical tips for elevation., Results:  Five different planes of elevation for perforator flaps are identified: subfascial, suprafacial, superthin, ultrathin, and subdermal (pure skin) layers based on experience, literature, and anatomy., Conclusion:  These planes all have their unique properties and challenges. Understanding the benefits and limits along with the technical aspect will allow the surgeon to better apply the perforator flaps., Competing Interests: None declared., (Thieme. All rights reserved.)

Background:  This study aimed to evaluate the usefulness of the selective use of the superficial circumflex iliac artery perforator (SCIP) and the superficial inferior epigastric artery (SIEA) flap as a workhorse flap from the groin area with precise preoperative surgical planning., Methods:  A total of 79 free flap reconstructions were performed in the study period; 35 SCIP free flaps and 19 SIEA free flaps were performed in the study period. Detailed preoperative surgical planning was performed using computed tomography (CT) angiography and color Doppler ultrasound. Detailed anatomical information of the flaps and reconstructive outcomes were evaluated., Results:  Flap characteristics between SCIP free flaps and SIEA free flaps were similar. The average transverse distance of the perforator from anterior superior iliac spine was 15.91 cm in SCIP free flaps and 43.15 cm in SIEA free flaps. The overall flap success rate was 96.4%. Majority of the patients achieved satisfactory contour without debulking surgery. Donor site morbidity was minimal with one case of wound dehiscence., Conclusion:  The selective use of the SCIP and SIEA free flap in groin area is a safe and useful technique. The surgical outcomes were reliable and similar between the SCIP and SIEA free flaps. Preoperative vascular planning using CT angiography and color Doppler ultrasound is essential for selecting the proper flap., Competing Interests: None declared., (Thieme. All rights reserved.)

Background:  The local flaps, especially perforator and keystone flaps, are used as first-line treatment option in reconstruction of small tomoderate-sized defect of the extremity. However, the high complication rate associated with these flaps may hinder this usage., Methods:  This article reviews the technical and clinical aspect of using color duplex ultrasound )CDU) in the preoperative, intraoperative, and postoperative period for propeller and keystone flaps., Results:  CDU allows the surgeon to understand the anatomical aspect of the perforator such as the location, point of penetration on the deep fascia, subcutaneous pathway )axiality) and physiological aspect such as velocity and flow volume. Understanding and utilizing this information will allow accurate preoperative design, intraoperative decision making, and postoperative monitoring, leading to better outcome., Conclusion:  Carefully designed local perforator flaps based on anatomy and physiology using CDU will be a powerful armamentarium for reconstruction of the lower extremity., Competing Interests: None declared., (Thieme. All rights reserved.)

Background:  Among the many factors involved in reconstructive microsurgery, identifying a good recipient vessel is one of the key elements leading to a successful result., Methods:  Multiple modalities have been used to identify recipient vessels from simple palpation of axial arteries to hand-held Doppler, duplex ultrasound, computed tomography angiograms, and other advanced techniques. Although these various modalities bring their own unique advantages, using the duplex ultrasound can provide far superior and real-time information based on the anatomy and physiology of the recipient vessel., Results:  Duplex ultrasound is a valuable and powerful tool for reconstructive surgeons who are interested in performing microsurgery or supermicrosurgery., Conclusion:  As we enter the era of individualized/customized reconstruction using superthin flaps, perforator-to-perforator anastomosis, and supermicrosurgery, understanding and becoming versatile with duplex ultrasound will be critical especially in choosing recipient vessels., Competing Interests: None declared., (Thieme. All rights reserved.)

Background:  Transmetatarsal amputation (TMA) preserves functional gait while avoiding the need for prosthesis. However, when primary closure is not possible after amputation, higher level amputation is recommended. We hypothesize that reconstruction of the amputation stump using free tissue transfer when closure is not possible can achieve similar benefits as primarily closed TMAs., Methods:  Twenty-eight TMAs with free flap reconstruction were retrospectively reviewed in 27 diabetic patients with a median age of 61.5 years from 2004 to 2018. The primary outcome was limb salvage rate, with additional evaluation of flap survival, ambulatory status, time until ambulation, and further amputation rate. In addition, subgroup analysis was performed based on the microanastomosis type., Results:  Flap survival was 93% (26 of 28 flaps) and limb salvage rate of 93% (25 of 27 limbs) was achieved. One patient underwent a second free flap reconstruction. In the two failed cases, higher level amputation was required. Thirteen flaps had partial loss or other complications which were salvaged with secondary intension or skin grafts. Median time until ambulation was 14 days following reconstruction (range: 9-20 days). Patients were followed-up for a median of 344 days (range: 142-594 days). Also, 88% of patients reported good ambulatory function, with a median ambulation score of 4 out of 5 at follow-up. There was no significant difference between the subgroups based on the microanastomosis type., Conclusion:  TMA with free flap reconstruction is an effective method for diabetic limb salvage, yielding good functional outcomes and healing results., Competing Interests: None declared., (Thieme. All rights reserved.)

Successful reconstruction of diabetic ulcers using free flap surgery can prevent further amputation and promote limb salvage to maintain normal gait of the patient and increase the quality of life after surgery. To minimize the postoperative complication and days of stay in hospital, surgeons should thoroughly investigate the risk factors and underlying conditions, including the general condition and local factors., Competing Interests: None declared., (Thieme. All rights reserved.)

Background:  Successful lower extremity reconstruction using free flaps begins by identifying a good recipient vessel and understanding the surrounding environment of the defect., Methods:  One should consider multiple factors when selecting the recipient vessel such as the status of the axial arteries, trying to preserve flow as much as possible, extent and severity of the defect, and ultimately what type of anastomosis will be ideal., Results:  Multiple factors of importance are reviewed and show the relevance in decision making and provide an algorithm., Conclusion:  In addition to the multiple factors to be considered, the ultimate decision should be made on the table during surgery when the actual artery or vein is exposed and shows signs of good pulsation and flow., Competing Interests: None declared., (Thieme. All rights reserved.)

Background:  There are various advantages and disadvantages attributed to superficial circumflex iliac artery perforator (SCIP) flap. The aim of this study is to evaluate the versatility and reliability of free SCIP flap by performing a systematic review and meta-analysis of the literature in terms of flap characteristics, pedicle types, and outcomes, including the different types of flap elevations., Methods:  PubMed, Embase OVID, and Cochrane CENTRAL were searched up to January 2019. All original articles and case reports published in English were included in the analysis. Anatomic descriptions, cadaveric studies, conference presentations, letter to the editors, local SCIP flaps, and review articles were excluded., Results:  A total of 36 articles including 907 SCIP flaps were available for the analysis. The most frequent causes of defects were tumors (38.2%) and lower extremities were the most common recipient areas (62.7%). The average flap dimension was 73.3 ± 23.0 cm 2 with a pedicle length of 5.0 ± 0.6 cm. Vessel diameter average was 0.67 ± 0.12 mm. The average number of deep branch and superficial branch used per study was 14.4 ± 8.7 (18%) and 93.3 ± 75.0 (84%), respectively. Flap failure rate and complication rate were 2.7 and 4.2%, respectively., Conclusion:  SCIP flaps have been shown to be versatile in various aspects of reconstruction. The attributed disadvantages such as having short pedicle and small vessel diameter do not seem to limit the variable usage of this flap. Therefore, SCIP flap should be considered a workhorse flap., Competing Interests: None declared., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background:  With the technological advances, microsurgery has evolved to the era of supermicrosurgery since its inception. With the popularization of these flaps, proficiency in using tools such as color Doppler ultrasound (CDU) has become crucial. Despite the increased interest, studies regarding the role of ultrasound in microsurgical reconstruction are scarce. Therefore, in this study, we discussed currently available imaging modalities for reconstructive surgeons, types of ultrasound, and the role of ultrasound in microsurgical reconstruction, and made recommendations for ultrasound use in reconstructive surgery., Methods:  We performed a computerized search of ultrasound in reconstructive surgery using the MEDLINE database. Data regarding ultrasound indications, usage, and outcomes were collected., Results:  Of the 115 articles identified, the majority was written on nonreconstructive ultrasound uses (51.4%). For the reconstructive uses, mapping of perforators was the most common usage (39.1%), followed by flap monitoring and volume measurement. In addition, we found that there are a limited number of literature on the role of CDU in reconstructive surgery, especially on its intraoperative and postoperative use., Conclusion:  CDU is a valuable and powerful tool for any reconstructive surgeons who are interested in performing microsurgery or supermicrosurgery. As the demand of customized flaps using superthin flaps, perforator-to-perforator anastomosis, and supermicrosurgery increases, understanding and becoming versatile in CDU will be critical. We hope our experience with using ultrasound and refinements that we made are helpful for those who would like to include it as a part of their armamentarium., Competing Interests: None declared., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background:  Overall success rate after diabetic foot reconstruction using free flap has been acceptable, but certain parts of the foot like the heel remains more challenging., Patients and Methods:  This retrospective study reviewed 37 patients reconstructed with free flaps for diabetic foot ulcer on the heel region from 2008 to 2017. Flap outcome in addition to various risk factors were analyzed; arterial status on heel, the American Society of Anesthesiologists (ASA) physical status, smoking, hypertension, hypercholesterolemia, chronic renal failure patient, hemoglobin A1c level, C-reactive protein, and osteomyelitis., Results:  Overall flap survival was 73% and resulted in limb salvage and functional ambulation. Total flap loss was 27% and the majority ended up with high-level amputation. Among the risk factors evaluated, the arterial status of the heel and ASA status significantly increased the odds for failure. When both arterial branches to the heel were impaired, the odds of failure were 80 times higher to fail ( p < 0.05)., Conclusion:  The vascularity of the surrounding tissue of the defect plays a critical role in overall success of diabetic heel reconstruction. Aggressive debridement using the angiosome concept is necessary to assure surrounding tissue has a good circulation. Despite the high chance of failure, success will lead to limb salvage and to reasonable functional ambulation whereas failure to salvage the heel will lead to higher level amputation. This warrants microsurgeons to make an effort to perform reconstruction to the heel defect after obtaining maximal vascularity after angioplasty., Competing Interests: None declared., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background:  Statins are traditionally used in lowering cholesterol and low-density lipoprotein biosynthesis, but recent reports show their beneficial effect on microcirculation. The aim of this study was to investigate the effect of simvastatin on the microcirculation and in conjunction with aspirin in a rat free epigastric flap model., Methods:  Thirty-six Sprague-Dawley rats were divided into group A (control, n  = 12), group B (simvastatin treated, n  = 12), and group C (simvastatin and aspirin, n  = 12). Bilateral free epigastric skin flap was used to evaluate the effect. At 48 hours, flaps biopsies were evaluated for inflammatory activity, nitric oxide content, and thrombomodulin regulation in the endothelial lining of microvessels. Flap survival was evaluated on day 7., Results:  The diameter of microvessels and nitric oxide activity in groups B and C were significantly higher than in group A ( p  < 0.005 and 0.015, respectively). The perivascular inflammatory cell infiltrates and intravascular adhesions were predominant in group A compared with groups B and C ( p  < 0.005). Groups B and C demonstrated significant higher degree of thrombomodulin expression. The flap survival rate on day 7 was 70.8% for group A, and 87.5% and 91.7%, respectively, for groups B and C without significance between the two ( p  = 0.675)., Conclusion:  Simvastatin significantly improves the free flap survival by effective anti-inflammatory, vasodilator, and anticoagulant activities. Combined therapy did not have an antagonistic effect and further study is needed to see synergistic action through different mechanisms., Competing Interests: None declared., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background:  This study was conducted to evaluate the impact of choosing a particular recipient venous system on venous patency and flap survival in 652 head and neck free flap reconstructions., Methods:  A retrospective review was performed. Patient factors investigated included: age, sex, type of flap, tumor location, history of radiation, presence of previous neck dissection, tumor stage, and any underlying disease. Data related with recipient vein including the number of anastomosis, the repair technique, the type of recipient vein, and the configuration of selected venous system were examined. The impact of patient factors and parameters related with recipient vein on the venous patency and flap survival were analyzed using bivariate and multivariate analyses., Results:  Of 652 free flaps, 36 flaps (5.5%) were re-explored due to venous congestion and 28 flaps (77.8%) were salvaged. The overall survival rate of total free flaps was 98.8%. The type of recipient venous system was found to be an insignificant factor with respect to venous congestion and flap survival in multivariate analysis. A history of radiation treatments was the only factor associated with a higher risk of venous compromise (odds ratio [OR] = 13.138, p  < 0.001) and a lower rate of flap survival (OR = 20.182, p  = 0.002)., Conclusion:  The selection of recipient venous systems has no impact on venous patency and flap survival. History of radiation treatment was the only factor associated with venous congestion and flap failure. Since no single method can ensure a successful reconstructive result, selecting the optimal recipient vein should be based on individual patient factors and the surgeon's experience., Competing Interests: None declared., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background:  This article investigates the effect of 180° rotating propeller flaps and evaluates whether each flap has a "preferable" rotating direction., Methods:  Part 1 evaluates the flap pedicle velocity and flow volume in neutral, 180°counterclockwise, and clockwise rotated position for 29 c onsecutive flaps. The data (velocity and volume) were divided into three groups: neutral, high value, and low value group then evaluated. Part 2 compares the outcome from the prospective study where a preferable rotation with high value was selected against 29 patients from 2012 to 2016 who had the same operation without selecting a preferable rotation direction., Results:  In part 1, the three groups (neutral, high value, and low value groups) showed mean velocity of 28.06 ± 7.94, 31.92 ± 10.22, 24.41 ± 8.12 cm/s, respectively, and mean volume of 6.11 ± 4.95, 6.83 ± 6.69, 4.62 ± 3.55 mL/min, respectively. The mean velocity and volume of the perforator in the high value group were significantly higher than that in the low value group ( p  = 0.0001). In part 2, although no statistical significance in the outcome was observed, there were two cases of total, two cases of partial flap loss, and three cases of wound dehiscence in the patients where preferable rotations was not selected compared with only two wound dehiscence for flaps with preferable rotation., Conclusion:  The velocity and flow of the flap are significantly different based on the rotation direction of the flap. Using the preferred rotation direction with statistically higher value of velocity and flow may increase the overall outcome of the propeller flap, especially where larger flaps are used., Competing Interests: None declared., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background:  Due to the concern of circulation compromise, many surgeons hesitate to dangle or challenge the flap in the early postoperative phase. In our experience, early compression may have advantages such as collapse of dead space, evacuation of hematoma, reduction of edema, and stabilization of flap when ambulating. In this study, the effect of early compression of flaps with regard to flap physiology and outcome is evaluated., Methods:  From postoperative day 3 to 5, a custom-made compression garment was fitted aiming to compress with a pressure of 30 to 35 mmHg. A total of 52 patients (52 flaps) were enrolled for the study and 48 flaps underwent early compression. The compression was applied not only over the flap but also over the extremity or trunk. The flap outcome as well as flow velocity and flow volume of the pedicle before and after compression was measured and evaluated., Results:  There was no flap complication during the early compression and early ambulation. And, there was no statistical difference either in the flow velocity or in the volume before and after the compression therapy (29.21 vs. 29.42 cm/s and 7.13 vs. 6.56 cm 3 /s, respectively)., Conclusion:  Early compression with a 30-mmHg pressure customized pressure garment after the flap surgery does not affect the hemodynamics of the perforator and can be safely used after extremity reconstruction before ambulation., Competing Interests: None declared., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background:  The superficial femoral artery (SFA) is the most common site of lower extremity atherosclerosis, and collateral vessels from the deep femoral artery (DFA) play an important compensatory role between the iliofemoral segment and the popliteal artery. We examined SFA occlusion and collateral vessel developments in patients with diabetes mellitus using computed tomography (CT) angiography. We also compared the collateral systems from the DFA and the descending branch of the lateral circumflex femoral artery (dbLCFA) in the case of SFA occlusion., Methods:  We retrospectively reviewed 1,316 sets of CT angiographic data collected from 673 patients with diabetes between 2008 and 2010. The degree of stenosis in each segment of the proximal and distal SFA and the number and size of collateral vessels originating from the DFA and dbLCFA were measured using established scoring systems. In cases where the SFA was occluded, the numbers of collateral vessels originating from the DFA and the dbLCFA vessel were compared., Results:  The mean occlusion rate of the SFA was 15.6%. We noted that collateral vessels from DFA and dbLCFA were the main circulatory route in cases of occlusions of the SFA. More collateral vessels developed from the DFA than from the dbLCFA. Overall, 0.6% of the patients had only collateral systems from the dbLCFA., Conclusion:  When planning to use anterolateral thigh free flaps in diabetic patients with suspected SFA total occlusion, thorough investigations of the peripheral vessels are essential., Competing Interests: Conflict of Interest: None., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Competing Interests: Financial Disclosure: The authors have no financial interest to declare about the content of this article.