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Background:  The anterolateral thigh (ALT) perforator flap is a commonly used flap with a predictable, though often variable, perforator anatomy. Preoperative imaging with color Doppler ultrasound (CDU) and computed tomography angiography (CTA) of ALT flap perforators can be a useful tool for flap planning. This study provides a complete review and analysis of the relevant preoperative ALT imaging literature., Methods:  Studies related to preoperative CDU and CTA imaging were reviewed, and information related to imaging method, sensitivity, false-positive rates, and perforator course identification (musculocutaneous vs. septocutaneous) were analyzed., Results:  A total of 23 studies related to preoperative ALT flap CDU and CTA imaging were included for review and analysis. Intraoperative perforator identification was compared with those found preoperatively using CDU ( n  = 672) and CTA ( n  = 531). Perforator identification sensitivity for CDU was 95.3% (95% CI: 90.9-97.6%) compared with the CTA sensitivity of 90.4% (95% confidence interval [CI]: 74.4-96.9%). The false-positive rate for CDU was 2.8% (95% CI: 1.1-4.5%) compared with 2.4% (95% CI: 0.7-4.1%) for CTA. Accuracy of perforator course identification was 95.5% (95% CI: 93.6-99.2%) for CDU and 96.9% (95% CI: 92.7-100.1%) for CTA., Conclusion:  CDU provides the reconstructive surgeon with greater preoperative perforator imaging sensitivity compared with CTA; however, false-positive rates are marginally higher with preoperative CDU. Preoperative imaging for ALT flap design is an effective tool, and the reconstructive surgeon should consider the data presented here when selecting a flap imaging modality., Competing Interests: None declared., (Thieme. All rights reserved.)

Background:  Preoperative knowledge of themicrovascular anatomy of a patientmay improve safetyand efficacy and reduce morbidity. Today, with the advancement in technology, ultrasound can provide minute details of the structures within the body, which makes this technology very helpful in preoperative evaluation of the traditional perforator flaps as well as thin, superthin, and pure skin perforator flaps., Methods:  In this article, we will describe the design of one of the most popular perforator flaps, the anterolateral thigh (ALT) flap, using high-frequency and ultrahigh-frequency ultrasound technology., Results:  Ultrasound technology allows to study preoperatively the ALT donor-site and its microvascular anatomy by using different US modalities in order to provide a virtual surgical plan to the operating surgeon., Conclusion:  Ultrasound technology allow to expand preoperative knowledge of flap microvascular anatomy and its course within the subcutaneous tissue up to and within the dermis, allowing to select the best perforator for the given reconstruction and the plane of elevation for thin, superthin and pure skin perforator flap., Competing Interests: G.V. and A.H. are Medical Advisors for Fujifilm Japan. A.B. and M.S. have no interest in any of the products, devices, or drugs mentioned in this manuscript., (Thieme. All rights reserved.)

Background:  A chimerically configured gracilis and profunda artery perforator (PAP) flap is highly prevalent based on recent computed tomography (CT)-imaging data. The purpose of this study is to further characterize the vascular anatomy of this novel flap configuration and determine the feasibility of flap dissection., Methods:  To characterize flap arterial anatomy, lower extremity CT angiograms performed from 2011 to 2018 were retrospectively reviewed. To characterize venous anatomy and determine the feasibility of flap harvest, the lower extremities of cadavers were evaluated., Results:  A total of 974 lower extremity CT angiograms and 32 cadavers were included for the assessment. Of the 974 CT angiograms, majority (966, 99%) were bilateral studies, yielding a total of 1,940 lower extremities (right-lower-extremity = 970 and left-lower-extremity = 970) for radiographic evaluation. On CT angiography, a chimerically configured gracilis and PAP flap was found in 51% of patients ( n  = 494/974). By laterality, chimeric anatomy was present in 26% of right lower extremities ( n  = 254/970) and 25% of left lower extremities ( n  = 240/970); bilateral chimeric anatomy was found in 12% ( n  = 112/966) of patients. Average length of the common arterial pedicle feeding both gracilis and PAP flap perforasomes was 31.1 ± 16.5 mm (range = 2.0-95.0 mm) with an average diameter of 2.8 ± 0.7 mm (range = 1.3-8.8 mm).A total of 15 cadavers exhibited chimeric anatomy with intact, conjoined arteries and veins allowing for anatomical tracing from the profunda femoris to the distal branches within the tissues of the medial thigh. Dissection and isolation of the common pedicle and distal vessels was feasible with minimal disruption of adjacent tissues. Chimeric flap venous anatomy was favorable, with vena commitante adjacent to the common pedicle in all specimens., Conclusion:  Dissection of a chimeric medial thigh flap consisting of both gracilis and PAP flap tissues is feasible in a cadaveric model. The vascular anatomy of this potential flap appears suitable for future utilization in a clinical setting., Competing Interests: None declared., (Thieme. All rights reserved.)

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 ( p  = 0.015), decreased surgeon uncertainty to 4% compared with 41% with white light alone ( p  = 0.011), and improved inter-rater agreement from 53.1% with white light alone to 91.8% ( p  = 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., Competing Interests: C.L. is employed by OnLume, Inc.; A.J.U. is a co-founder and employee of OnLume, Inc.; K.W.E. is a co-founder of OnLume, Inc. The other authors report no conflict of interest., (Thieme. All rights reserved.)

Background:  Preoperative ultrasound (US)-guided perforator mapping has immensely simplified perforator flap planning. It may be executed by the microsurgeon. Device settings and selection of ultrasound modes are of utmost significance for detection of low-flow microvessels. The following study evaluates different US modes., Methods:  A prospective complete data acquisition was performed from July 2018 to June 2019 in a subset of patients who underwent US-guided flap planning. Multifrequency linear transducers were used applying five US modes. Brightness (B)-mode, color flow (CF), power Doppler (PD), pulse wave (PW), and B-flow modes were evaluated regarding applicability by microsurgeons. Peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) were chosen to evaluate flow characteristics. US results were correlated to intraoperative findings., Results:  A total number of eight patients (six males and two females) undergoing anterolateral thigh (ALT) or superficial circumflex iliac artery perforator (SCIP) flap surgery received an extensive standardized US-guided perforator characterization. Qualitative evaluation was performed in B-mode, color-coded duplex sonography (CCDS), PD, and B-flow mode. Quantitative assessment was executed using PW-mode and CCDS measuring the microvessels' diameter (mm) and flow characteristics (PSV, EDV, and RI). CCDS provided a mean diameter of 1.93 mm (range: 1.2-2.8 ± 0.51), a mean systolic peak of 16.9 cm/s (range: 9.9-33.4 ± 7.79), and mean RI of 0.71 (range: 0.55-0.87 ± 0.09) for lower limb perforators. All perforators located with US were verified by intraoperative findings. An optimized, time-effective US mapping algorithm was derived. Qualitative parameters may be evaluated with B-mode, CF, or B-flow. Smallest microvessels may be assessed in PD-mode. Lowering pulse-repetition frequency (PRF)/scale is mandatory to image low-flow microvessels as perforators. Quantitative information may be obtained using PW-mode and the distance-measuring tool in CF-mode. Image and video materials are provided., Conclusion:  CCDS proved to be a powerful tool for preoperative perforator characterization when using a structured approach and mapping algorithm. Different techniques may be applied for specific visualizations and performed by the microsurgeon., Competing Interests: None declared., (Thieme. All rights reserved.)

Background:  Perforator imaging is routinely performed before perforator flap harvest. Hand-held Doppler (hhD) and color duplex ultrasonography (CDU) are currently the most popular radiation-free methods for this purpose that can be applied by the surgeon alone. The aim of this study was to compare the accuracy, reliability, and feasibility of hhD and CDU with indocyanine green angiography (ICGA) in the anterolateral thigh perforator flap (ALTPF)., Methods:  All consecutive ALTPF procedures between May 2017 and April 2018 were included in this prospective study. The perforators were visualized by three investigators independently and randomized, applying hhD, CDU, and ICGA. The presence and the distance to the identified perforator were registered. Further, body mass index (BMI), American Society of Anesthesiologists-status, and the patient's history regarding smoking, alcohol use, and diabetes mellitus were registered alongside gender and age to analyze possible confounders., Results:  A total of 12 patients were enrolled with a median age of 67 (52-87) years. In total, 30 perforators were detected intraoperatively as well as with the ICGA. The latter visualized the perforators significantly more precisely than hhD and CDU ( p  < 0.001 and p  = 0.001). The sensitivity and positive predictive value were 67 and 62% for hhD, 73 and 64% for CDU, and 100 and 100% for ICGA, respectively., Conclusion:  According to this study, ICGA visualized perforators more accurately than the standard methods hhD and CDU. Further, it was associated with the highest sensitivity and positive predictive value. ICGA consistently delivered excellent results, whereas hhD and CDU showed variability., Competing Interests: None declared., (Thieme. All rights reserved.)

Background:  The anterolateral thigh (ALT) flap is a useful flap with minimal donor site morbidity. Preoperative computed tomographic angiography (CTA) for lower extremity reconstruction can determine vessel integrity and plan for recipient vascular targets. This study reviews lower extremity CTAs to further characterize ALT vascular anatomy and associated clinical implications thereof., Patients and Methods:  Lower extremity CTA studies were retrospectively reviewed, and information on ALT cutaneous perforator location, origin, and course was collected., Results:  A total of 58 lateral circumflex femoral artery (LCFA) systems in 31 patients were included. Average age was 38.8 ± 15.9 years with mean body mass index of 27.2 ± 5.7 kg/m 2 . The majority of patients were females (23, 74.2%). The LCFA most commonly originated from the profunda femoris artery (87.3%), followed by the distal common femoral artery (9.1%). On average, there were 1.66 ± 0.69 cm perforators per extremity, with an average of 5.38 cm between adjacent perforators. Perforators originated from the descending branch of the LCFA in 89.6% of studies. Perforator caliber was <1 mm (29, 30.2%), 1 to 2 mm (55, 57.3%), or >2 mm (12, 12.5%). Mean distance from the most proximal perforator to the anterior superior iliac spine was 20.4 ± 4.82 cm. Perforators were musculocutaneous (46.9%), septocutaneous (34.4%), or septomyocutaneous (18.8%). In 58.1% of patients, only one thigh had easily dissectable septocutaneous and/or septomyocutaneous perforators, in which case preoperative CTA aided in donor thigh selection., Conclusion:  ALT flap cutaneous perforator anatomy varies considerably. Using CTA, we report on rates of septocutaneous, myocutaneous, and septomyocutaneous perforators and underscore its utility in perforator selection., Competing Interests: None declared., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Competing Interests: None declared.

Background:  Novel secondary flap options are paramount for patients who are not candidates for common reconstructive methods. The purpose of this study is to identify the prevalence of single arterial pedicle supplying both the gracilis muscle and medial thigh tissue carried in a profunda artery perforator (PAP) flap. Such a pedicle could allow the creation of a chimeric gracilis and PAP flap with a single-arterial anastomosis., Methods:  We conducted a retrospective review of 157 lower extremity computed tomography (CT) angiograms to assess the vasculature of the thigh soft tissues. Imaging evaluation was supervised by a board-certified musculoskeletal radiologist., Results:  Prevalence of a single-arterial pedicle to a gracilis and PAP flap in each patient was 59% (31% within the right leg and 28% in the left leg). Furthermore, 16% of patients had a common arterial pedicle in both lower extremities., Conclusion:  Existence of a single-arterial pedicle to both the gracilis muscle and PAP flap tissues is frequently present in most patients in at least one lower extremity. This chimeric flap configuration could serve as a reconstructive avenue for patients, particularly those who have exhausted other more common flap options. Screening angiography is warranted in patients looking for this anatomic variation to establish its presence., Competing Interests: None declared., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background:  To harvest any flap on the lateral circumflex femoral artery (LCFA) including tensor fasciae latae (TFL) muscle, a precise description of the vascular anatomy is required. There have been conflicting reports of the vascular supply of TFL and its overlying skin. The objective of this study was to evaluate the anatomy of the TFL muscle according to the location, origin, type, caliber, and length of vessels that supply the muscle., Methods:  This study was performed on human cadavers ( n  = 16 thighs) that were injected with a mixture of lead oxide and gelatin through the femoral artery. Whole body computed tomography scans were performed. Three-dimensional images of the arterial anatomy were created using Materialise Interactive Medical Image Control Software (MIMICS). Anatomical dissection of all cadaver thighs was performed to visualize the arterial blood supply of the muscle and its regional perforators., Results:  Sixteen thighs were included in the study. The main arterial supply of the TFL muscle was in all cases, the ascending branch of the LCFA (LCFA-asc) artery. The mean external diameter of the LCFA-asc artery was 2.7 mm ± 0.4 and the mean length was 3.6 cm ± 0.6. The distance from the anterior superior iliac spine to point where the vascular pedicle reaches the muscle ranged from 6.7 to 10.2 cm. The average number of cutaneous perforators was 10.9 ± 4. There were musculocutaneous perforators in all of our dissections ( n  = 16) and 14 of our specimens had septocutaneous perforators., Conclusion:  The main vascular supply to the TFL muscle is the ascending branch of the LCFA, which also gives rise to septocutaneous and musculocutaneous perforators. MIMICS provides excellent three-dimensional anatomical information about the vascular supply of the TFL., Competing Interests: The authors state there are no disclosures or financial conflicts in performing this study., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background:  Variations in anterolateral thigh (ALT) arterial anatomy are well documented. Ethnicity is a known risk factor for vascular variation in several organ systems, but its impact on ALT anatomy has not been studied. Anecdotally, we observed frequent ALT arterial variation in African American (AA) patients. We thus hypothesized that AA patients have higher rates of anomalous branching., Materials and Methods:  A total of 277 computed tomography angiograms (513 lower extremities) captured between May 1, 2013 and May 31, 2015 at a tertiary academic medical center were retrospectively analyzed to determine ALT arterial branching. Patient records were examined to ascertain demographics. Data were analyzed using descriptive statistics and multinomial logistic regression., Results:  Males comprised 84.5%. Ethnic distribution was 55.2% AA and 36.5% Caucasian. The descending branch of the lateral circumflex femoral artery (dLCFA) originated from non-LCFA arteries (deep femoral, common femoral, or superficial femoral arteries) in 18.9% of Caucasian versus 9.1% of AA (odds ratio [OR]: 2.28; 95% confidence interval [CI]: 1.33-3.93, p  < 0.01). An oblique branch was identified in 41.1% of Caucasian versus 51.9% of AA (OR: 1.56; 95% CI: 1.08-2.24, p  = 0.02). Ethnicity was the only driving factor of dLCFA and oblique branch of the LCFA (oLCFA) anatomy (Wald chi-square: 14 and 11, p  = 0.03 and 0.02, respectively)., Conclusions:  Ethnicity significantly affects ALT arterial anatomy. AA are more likely to have classical dLCFA branching with a fourth oLCFA branch. A flap with an unrecognized oLCFA-dominant supply places patients at a higher risk for flap failure and loss. We recommend preoperative imaging before undertaking an ALT flap reconstruction., Competing Interests: Drs. Toshav and Lau have no conflict of interest. No funding was received for this article., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background  The chimeric anterolateral thigh (ALT) flap has been an ideal option for restoring complex soft tissue defects. However, as the vascular anatomy of the ALT is variable, the positions of its perforators are uncertain, which makes the surgery more challenging. Therefore, our study utilized computed tomographic angiography (CTA) for preoperative perforator mapping. Methods  From October 2013 to October 2015, 37 patients suffering upper extremity soft tissue defects underwent CTA before ALT flap reconstruction. Perforators originating from the same source vessel were mapped by CTA, and the donor thigh and preferred perforators were selected accordingly. All preoperative parameters of perforators detected by CTA were checked during operation. Results  Thirty-three dual-skin paddles, three tri-skin paddles, and one quad-skin paddles flap were designed and used in this study. Eighty-seven perforators were mapped by CTA preoperatively. Seventy-nine (90.8%) were used; 97.5% of these were musculocutaneous and 2.5% septocutaneous. All perforators used intraoperatively were consistent with preoperative parameters. Post-operatively, 2 patients experienced complications but there was 100% flap survival overall. The donor sites primarily underwent primary closure, apart for 7 cases which underwent skin grafting. There was no donor site morbidity. Conclusion  Preoperative mapping by CTA is a useful, fast, and noninvasive method for assessing the source vessels, and can be a significant aid in chimeric ALT flap surgery., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background: The anterolateral thigh (ALT) flap has been widely used in reconstruction of soft tissue defects. The anatomic variations of perforators increase the difficulties of flap elevation. The ABC system has been described for locating the most common three perforators in Western populations. Less evidence has been found regarding whether it is suitable for Chinese population. The purpose of this study is to explore the improvement of preoperative location technology and flap design for Chinese people., Methods: Detection for perforator signals on the bilateral thigh surface was perfromed on 50 Chinese adults using handheld Doppler. Define the A-P line as the line between the anterior superior iliac spin (ASIS) and the superolateral corner of the patella (P). We defined a coordinate system on the thigh surface to record the data of each signal point. The A-P line was y-axis in this coordinate system, and the midpoint of the line was the zero point. The data of these signals were recorded in the form of coordinates. Statistics and mathematic methods were used to analyze the regularity of signal distribution and the correlation between body mass index (BMI) and signal distribution. The findings were applied in five patients who underwent the ALT flap transplantation to confirm its clinical value., Results: The results showed that most of the signals appeared near the A-P line. Most signals were located 1 cm lateral (mean 0.5 cm lateral) to the A-P line. The mean vertical distance between perforator B and perforators A and C was 4 cm. More perforator signals were detected at the two horizontal level (as shown in the picture above) than other horizontal levels. The rate of accurate preoperative detection was 40% (6 of 15 perforators) and the error rate was 20% (3 of 15 perforators). The mean deviation was 1.34 cm, which is acceptable for clinical application. The mean vertical distance between perforator B and perforators A and C in clinical study (4.81 cm) corresponded to the finding of the Doppler study (4.2 cm), whereas the mean distance between perforators and the A-P line (1.57 cm) was more than the Doppler finding (0.48 cm)., Conclusion: The A-P line is still a reliable guiding line for Doppler detection and flap design. The ABC system is suitable for the Chinese population but must be adjusted: perforator B is marked first at the midpoint and 0.5 cm lateral to the A-P line and perforators A and C are marked 4 cm distal and proximal to perforator B, respectively. In designing the flap, the region 3 cm around point B and the region between the two horizontal planes at point B and 4 cm lower should both be contained into the flap, no matter what the finding of Doppler detection is., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

The anterolateral thigh (ALT) flap is now considered a workhorse for head and neck reconstruction in many centers. However, designing and raising the ALT flap has been traditionally recognized as being difficult, tedious, and technically demanding due to its variation in perforator anatomy. Designing the ALT flap on data gained solely using the handheld Doppler can be misleading, as its specificity and sensitivity varies greatly depending on amount of subcutaneous fat and the Doppler itself. Authors have investigated multiple imaging modalities in the search of the best way to predict and map the site and size of perforators before dissecting a flap. In this article, we describe a simplified technique for the ALT flap design and dissection without the use of preoperative imaging or vascular studies. Utilizing anatomic landmarks, the location of the three perforators (A, B, and C) can be anticipated and safely dissected. We conclude that accurate use of the ABC system is one approach in consistently dissecting the ALT flap.

Skin-flap thickness is an important consideration when choosing a free flap for head and neck reconstruction. The anterolateral thigh flap, the rectus abdominis flap, and the radial forearm flap, which included the epidermis, the dermal, and the subcutaneous layers, were measured using ultrasonography in 31 patients. The mean skin and subcutaneous thickness of the anterolateral thigh flap was 7.1 mm; the rectus abdominis flap was 13.7 mm; and the radial forearm flap was 2.1 mm. Further analysis revealed a statistically significant difference among the skin and subcutaneous thickness of the three flap groups. Of the 44 anterolateral thigh flap transfers done for head and neck reconstruction after cancer ablative surgery, 41 (93.2 percent) were transferred successfully. The anterolateral thigh flap creates a moderately thick skin flap, and is less variable in thickness across its area than is the rectus abdominis flap. The flap is adaptable for reconstruction of head and neck soft-tissue defects.