Computed Tomographic Angiography (CTA)-Guided Precision Reconstruction in Complex Lower Leg Wounds

Computed Tomographic Angiography (CTA)-Guided Precision Reconstruction in Complex Lower Leg Wounds | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Computed Tomographic Angiography (CTA)-Guided Precision Reconstruction in Complex Lower Leg Wounds Yueliang Zhu, Yongyue Su, Zehui Zhao, Sunwen Pan, Xi Yang, Yujian Xu, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7233679/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Reconstruction of complex lower leg wounds presents significant challenges due to extensive soft tissue damage, vascular variations, and potential neurovascular injuries. While flap transfer, particularly free flaps, remains the preferred method for reconstruction, the lack of precise preoperative vascular information often complicates surgical planning. This study introduces a Computed Tomographic Angiography (CTA)-guided approach for precision reconstruction to address these challenges. Methods From March 2013 to October 2023, 57 patients with complex lower leg defects underwent reconstruction using CTA-guided flap surgery. Patient demographics, injury characteristics, and surgical outcomes were retrospectively analyzed. Preoperative CTA was employed to map donor and recipient vascular anatomy, evaluate perforator vessels, and guide flap selection and design. Flap options included anterolateral thigh perforator (ALTP) and deep inferior epigastric perforator (DIEP) flaps, with selection tailored to wound dimensions, depth, and vascular conditions. Results Flap sizes ranged from 5×10 cm to 55×70 cm, 54 flaps survived completely (94.7%), one partial necrosis requiring revision (1.8%), and two total flap losses (3.5%). CTA demonstrated 100% concordance with intraoperative vascular findings, enabling precise recipient vessel localization and enhanced surgical efficiency. Postoperative complications included vascular compromise (8.8%), flap bulkiness (19.3%), and minimal wound dehiscence (1.8%). Functional and aesthetic outcomes were rated as excellent in 61.4% of cases. Conclusion The CTA-guided reconstruction approach enables comprehensive preoperative vascular assessment, optimizing donor flap selection and recipient vessel anastomosis. This evidence-based method significantly improves surgical precision and outcomes, representing an advancement over traditional empirical techniques in managing complex lower leg wounds. Computed Tomographic Angiography Perforator Flaps Lower Extremity Reconstruction Lower Leg Wounds Figures Figure 1 BACKGROUND AND INTRODUCTION Reconstruction of complex lower leg soft tissue defects represents a complicated reconstructive challenge.[ 1 ] [ 2 ]. Of various reconstructive interventions, flap transfer, especially free flap, remains a primary method for soft tissue defect reconstruction. Compared with pedicled flaps, free flaps can repair larger sizes of defects, restore well-vascularized soft tissue, and promote osteogenesis[ 3 , 4 ]. However, a seriously injured lower leg is often complicated by concomitant injuries to the major neurovascular structures. The inherent anatomic variability of the vasculature can make the selection of appropriate recipient vessels exceptionally challenging in the surgery. Meanwhile, the donor site anatomy, including the perforator vessels and their vascular pedicles, can be highly variable, further increasing the technical complexity of these reconstructive procedures. Without sufficient information of the vessels related to free flap transfer (donor site and recipient site), the most experienced surgeons[ 5 ] struggle to complete free flap transfers efficiently, often resulting in prolonged, exhausting procedures. The application of Computed Tomographic Angiography (CTA) technology has been extensively adopted within the field of reconstructive flap surgery. However, its current utilization has been primarily focused on the precise localization and dimensional assessment of the vascular anatomy within a designated flap[ 6 ]. The significance of CTA in evaluating recipient vasculature appears to be underemphasized, reflected by its limited scholarly coverage. The preoperative data pertaining to the recipient site serves not only as a crucial component in the harvesting of free flaps but also as a fundamental element in the amalgamation of information concerning the donor and recipient sites for vascular assessment, correlation, and the formulation of optimal procedural strategies. Research elucidating the amalgamation of these facets for the purpose of flap strategy development is notably scant, suggesting that the integration of these variables may yield substantive value in the strategic planning of flap procedures. Since March 2013, we have applied this CTA-guided, precision flap reconstruction methodology in the clinical management of 57 cases. A retrospective analysis of these patients was conducted, evaluating clinical outcomes based on flap perfusion assessment and other relevant metrics. PATIENTS AND METHODS 2.1 Patient Demographics and Injury Characteristics Over the 10-year period from March 2013 to October 2023, a total of 57 patients with complex lower extremity soft tissue defects underwent reconstruction using the CTA-guided precision technique. The cohort comprised 43 male and 14 female patients, with an age distribution ranging from 9 to 72 years and a mean age of 44.1 years. The etiologies of injury and the dimensions of the complex soft tissue defects of spanned a wide range (Table 1 ). In all cases, the reconstructive procedures were performed as delayed, elective interventions following initial wound debridement. Table 1 Patient demographics (n = 57) Number Patients Gender Distribution: Male 43 Female 14 Injury Etiologies: Machine-related trauma 7 Motor vehicle accidents 17 Crush injuries from heavy objects 12 Various infectious processes 3 Sharp lacerations 3 Falls from standing height 4 High-energy falls 7 Explosions 1 Tumors 1 Burns 1 Flap necrosis following previous reconstructive surgery 1 Defect Dimensions(cm*cm) 4*8–55*65 2.2 Preoperative CTA-based Vascular Mapping Methodology Patients were positioned supine with the lower extremities maintained in a neutral, extended alignment. Following intravenous administration of the iodinated contrast agent iohexol (35 g in 100 mL; Yangtze River Pharmaceutical Group, China), continuous CT angiographic imaging was performed from the abdomen to the feet using a 64-slice multidetector CT scanner (GE Healthcare, USA). The CT acquisition parameters were optimized at 120–140 kV, 525 mA, and a thin slice thickness of 0.625 mm. The high-resolution CTA datasets were then reviewed on a picture archiving and communication system (PACS) workstation to meticulously visualize the contrast-enhanced vasculature and identify the most suitable recipient vessels for the planned reconstructive procedure. The precise localization of the vessels and associated perforating branches was determined in reference to reliable bony landmarks using the following techniques: A:The longitudinal distance between the vessel/perforator and the bony landmark was calculated by measuring the difference in CT slice numbers between the two structures and multiplying by the isotropic slice thickness. B:The transverse distance between the bony landmark and the vessel/perforator was quantified on the PACS system by positioning the cursor on the bony landmark, maintaining the cursor position, scrolling to the plane of the vessel/perforator, and directly measuring the distance between the cursor and the vascular structure. This comprehensive CTA-based vascular mapping approach allowed for meticulous preoperative planning and localization of the key vascular anatomy, thereby facilitating the precision of the subsequent reconstructive intervention. 2.3 Recipient Vessel Selection The selection of appropriate recipient vessels is a critical step in preoperative planning for reconstructive procedures. The fundamental requirements for recipient vessel selection is the adequate visualization and opacification of the proximal recipient vessels on CTA. This ensures the patency and suitability of the vessels for microsurgical anastomosis. The sacrifice of the selected recipient vessels should not influence the distal perfusion of the affected limb. Maintaining adequate distal blood flow is paramount to prevent ischemic complications. The selected recipient vessels should be located outside of any zones of active inflammation or infection. The surrounding soft tissue and bony anatomy should be clearly delineated to facilitate the surgical dissection and anastomosis. When selecting the recipient vessels, the following priority factors should be considered: 1. Prioritizing the proximal end. We prioritize the proximal end for anastomosis by selecting the nearby artery and vein, as this facilitates the procedure and aligns blood flow with the recipient area. Although distal anastomosis is feasible, it would involve reversed flow in both the artery and vein. 2. Vessels located in close proximity to the wound. This would facilitate a tension-free anastomosis and minimize the length of the vascular pedicle. 3. Vessels with ease of exposure and accessibility. These vessels are readily identifiable and can be safely dissected to minimize surgical complexity and operative time. The specific recipient vessel selection should be tailored to the individual clinical scenario. After selecting the recipient vessels, the surgeon should meticulously document the distance between the vessels and the wound site, as well as the spatial relationship between the recipient vessels and the surrounding anatomical landmarks. This comprehensive preoperative vascular mapping is essential to ensure the precision and success of the reconstructive procedure. 2.4 Donor Flap Selection Based on the characteristics of the recipient vessels, as determined by computed tomographic angiography (CTA), the most commonly utilized donor flap options for lower extremity reconstruction is the anterolateral thigh perforator (ALTP) flap and the deep inferior epigastric perforator (DIEP) flap. When both ALTP and DIEP flaps meet the requisite criteria simultaneously, ALTP is prioritized owing to its similar flap thickness and characteristics. In scenarios where bilateral ALTP flaps satisfy the criteria, preference is given to the contralateral side due to the benefits conferred by tourniquet application and enhanced surgical maneuverability. The primary considerations in donor flap selection are: the Presence of reliable perforator vessels to adequately vascularize the flap. Adequate length and caliber of the vascular pedicle to reach and appropriately perfuse the recipient vessels. In scenarios where there exists a surplus of donor sites meeting the fundamental prerequisites for the flap, the determination of the flap type and selection of the donor site are predicated upon an assessment of the wound's depth and morphology. In instances of profound wound depth, conventional perforator flaps may prove inadequate for effective coverage, at this point, a muscle-containing myocutaneous flap can be selected to cover deeper soft tissue defects and obliterate dead space. For the broader or irregularly shaped wounds, wider single-perforator flaps may be preferable. Alternatively, the utilization of lobulated perforator flaps to construct a customized composite structure tailored for comprehensive wound coverage is warranted. For cross-leg flap reconstruction, given that the anastomosis site must be in the subcutaneous plane and the distance between the two crossed legs, the preferred option is to select a flap with an adequately long vascular pedicle. If the pedicle length of the chosen flap is insufficient, it becomes necessary to microsurgically harvest and transpose the posterior tibial artery and vein up to the recipient site for the microvascular anastomosis. In the region surrounding the exposed vascular pedicle of the cross-leg flap, the defect can be appropriately resurfaced utilizing thick split-thickness skin grafting [7]. 2.5 Surgical Planning and Execution At the donor site, the locations of the perforating vessels are plotted using a Cartesian coordinate system, delineating their positions along the horizontal and vertical axes. Based on the documented course of the vascular pedicle and the surrounding anatomical structures, a schematic diagram is meticulously created to illustrate the perforator locations and the detailed pedicle anatomy, with clear markings of important landmark structures. An analogous approach is employed to precisely map the positions of the recipient vessels. Guided by the principles of CTA-guided free flap design, the free flap harvest is typically performed in an antegrade fashion, as the perforator locations, pedicle length, and the intricate spatial relationships with the surrounding tissues have been thoroughly evaluated and accurately marked during the preoperative planning stage. This technique effectively mitigates the technical complexity of the dissection and facilitates a reduction in the overall operative duration, as it circumvents the need for time-consuming retrograde perforator identification. The DIEP flaps were meticulously crafted in polyfoliate configurations to optimize aesthetic outcomes, with the option of employing micro-thinning techniques when deemed necessary. 2.6 Postoperative Care and Monitoring In the postoperative period, the patient is managed in accordance with the standard protocols established for microsurgical reconstructive procedures. Measures are implemented to maintain normothermia and regulate the ambient temperature, while routine antimicrobial prophylaxis is administered to mitigate the risk of infectious complications. During the initial 72-hour postoperative period, the vascular status of the transferred flap is meticulously evaluated at 2-hourly intervals; this frequency is subsequently reduced to every 6 hours for the ensuing 72-hour period. In the event of any compromise in the vascular perfusion of the flap, prompt surgical exploration and timely intervention are undertaken to address the underlying etiology. The affected extremity is immobilized (usually by external fixation) for a period of 1-2 weeks in the postoperative phase to prevent traction on the vascular pedicle and to mitigate the risk of spasm. 2.7 Evaluation Criteria for Flap Blood Perfusion The assessment criteria for flap blood perfusion are delineated based on the guidelines for assessing finger replantation function as established by the Hand Surgery Division of the Chinese Medical Association. These standards gauge the vascular status of the flap through considerations encompassing skin coloration, temperature, and cold intolerance. Excellent: Manifesting normal skin color and temperature, devoid of the necessity for specialized protective measures; Good: Exhibiting a marginal deviation in skin coloration, coupled with a slightly diminished temperature and sensitivity to cold stimuli; Fair: Presenting with pallor or cyanosis in skin hue, along with a notable decline in temperature and heightened susceptibility to cold conditions; Poor: Featuring a dusky or cyanotic skin appearance, with a marked aversion to exposure in chilly environments. RESULTS In this series, flap sizes ranged from 5cm × 10 cm to 55 cm × 70 cm, with 52 cases of free anterolateral thigh perforator (ALTP) flaps and 5 cases of free deep inferior epigastric perforator (DIEP) flaps (Table 2 ). Complete flap survival was achieved in 54 cases, with 1 case demonstrating partial flap necrosis that required a repeat flap procedure resulting in successful salvage, and 2 cases of total flap loss (3.5%). Table 2 Basic Clinical Data of Flap Design in Patients (n = 57) Number Flap Sizes (cm*cm) 5*10–55*70 Flap Types Anterolateral thigh perforator (ALTP) flaps 52 Typical free flap 35 Septocutaneous flaps 4 Flow-through flaps 5 Musculocutaneous flaps 1 Chimeric flaps 3 Cross-leg flaps 4 Deep inferior epigastric perforator (DIEP) flaps 5 Flap Survival: 57 Complete survival 54 Partial necrosis requiring repeat procedure 1 Total flap loss 2 The microsurgical harvest of all flaps was accomplished in a meticulous and precise manner. Regarding donor site management, the preoperative CTA assessment of the recipient vascular origins, course direction, overall length, anastomosis sites, and vascular endpoints was found to be in complete agreement with the intraoperative anatomical findings, yielding a concordance rate of 100%. Primary closure was performed in 52 cases, while partial closure with subsequent skin grafting was undertaken in 4 cases, and secondary skin grafting after partial donor site necrosis in 1 case. According to the assessment of the recipient vessels in the leg of our results, the recipient vessels in the lower leg can exhibit 3 different types of presentation on CTA imaging due to factors such as trauma, anatomical variations, and the impact of internal/external fixation (Figure 1): A: The two main arterial trunks in the affected lower leg are continuous and take one arterial system as the recipient vessels would not compromise the distal perfusion. B: One of the main arterial trunks in the affected lower leg is continuous, while the other is unreliable. Taking this continuous vessel may potentially impair the distal perfusion of the leg. Consequently, the unreliable vessel stump may be selected as the recipient site (Type B1). If the stump is severely damaged and deemed unsuitable as a recipient site, the healthy posterior tibial artery of the contralateral side can be chosen instead (Type B2). In the absence of a healthy posterior tibial artery, an artery with a longer healthy vascular pedicle (medial or lateral sural artery) should be selected as the recipient site (Type B3). When considering the medial and lateral sural arteries as recipient vessels, it is essential to have a sufficiently long vascular pedicle of the flap for the cross-leg anastomosis; thus, the length of the donor area vessels must be carefully assessed prior to making a definitive decision. C: Both arterial trunks in the affected lower leg are unreliable and taking either one as recipient vessels may affect the distal perfusion. In this case, we would use flow-through flap technique. Types B and C are commonly observed in cases of comminuted tibial-fibular fractures, where internal/external fixation can lead to compression, distortion, or discontinuity of the main arterial trunks as observed on the CTA cross-sections. This comprehensive CTA-based assessment of the leg vascular anatomy is crucial for preoperative planning to ensure adequate distal perfusion is maintained during and after the reconstructive procedure. The typical cases of type A, B and C are illustrated in cases 1, 2 , 3 , and 4 . Typical cases: Case1 A: A 52-year-old male patient with an open fracture of the right lower leg, the wound size was 18cm×8cm, the internal fixation of plates and screws had been performed at the fracture site; B: Preoperative CTA outcomes (from anterior view); C: CTA imaging clearly delineates the anatomical course of the anterior tibial artery (ATA), posterior tibial artery (PTA), and fibular artery (FA) at the recipient site (right lower extremity), marked by black arrows, along with the morphology of the vascular stumps, indicated by red arrows. Digital reconstruction of the recipient site revealed continuity of only one group of main blood vessels, while the remnants of another vessel group were deemed viable, indicative of Type B1 collateral availability; D: Preoperative assessment via CTA identified several potential donor sites, with the left thigh meeting the necessary criteria for identifying a perforator and designing a flap; E: The left anterior lateral thigh flap was harvested precisely according to the preoperative plan; F: An anastomosis was established with the posterior tibial artery in the recipient area. The fractures were fixed with external fixation; G: One week postoperatively, the flap exhibited favorable shape and coloration. Case 2 A: A 53-year-old male patient with an open fracture of the left lower leg, the wound size was 7cm×7cm and the fractures were fixed with external fixation; B: Preoperative CTA outcomes (from posterior view); C: CTA imaging revealed the remnants of another vessel group (the anterior tibial vessels) were nonviable. However, the contralateral leg has an intact posterior tibial artery. Digital reconstruction assessment of the recipient site revealed continuity of only one group of main blood vessels(the posterior tibial vessels), the situation is consistent with Type B2 where the contralateral posterior tibial artery is present; D: Preoperative CTA-guided identification of a perforator in the donor site showed that the perforator pedicle of the right anterior lateral thigh flap was long enough for the design of a crossover flap; E: The intraoperative findings during flap harvesting revealed that the course and length of the vascular pedicle were completely consistent with the preoperative CTA examination; F: Vessels anastomosis was performed with the contralateral posterior tibial artery, the exposed vessel pedicle of the flap between the legs were skin-grafted; G: At one-month post-surgery, pedicle division was carried out, and the flap demonstrated successful survival. Case 3 A: A 45-year-old female with open fracture of the left lower leg, the wound size was 40cm×15cm and the fractures were fixed with external fixation; B: Preoperative CTA outcomes (from posterior view); C: CTA assessment of the recipient site revealed continuity of only one group of main blood vessels(the anterior tibial artery)in the left lower leg, with the remnants of another vessel group being unreliable for anastomosis. Meanwhile, the contralateral posterior tibial artery was absent, only had anterior tibial artery and peroneal artery (Type B3), which means the vessels of the contralateral leg were not suitable for anastomosis to the flap vessel pedicle; D: Preoperative CTA identified left ALTP flap had a long vessel pedicle of the intermuscular septal perforators, which matched the need of recipient site vessels’ anastomosi. Therefore, the left thigh was chosen as the donor site for the ALTP flap. E: The intraoperative findings were completely consistent with the preoperative CTA assessment. The flap had a long vessel pedicle; F: Anastomosis was performed with the medial sural artery; G: At a 5-month postoperative follow-up, the flap demonstrated successful survival. Case 4 A: A 53-year-old female sustained an open fracture of the right leg, the wound size was 20cm×15cm; B: Preoperative CTA outcomes (from anterior view); C: Preoperative CTA assessment of the recipient site indicated that neither group of blood vessels on the affected leg was continuous, consistent with Type C classification (red arrow); D : A flow-through ALTP flap was used to finish the wound coverage and restore the distal circulation, the fractures were fixed with external fixation; E: At one week postoperatively, the flap showed good survival. A follow-up period of 3 to 50 months was conducted for the cohort of 57 patients, during which the color, contour, and tissue quality of the transferred flaps were evaluated and deemed satisfactory. Clinical outcomes were categorized as follows: excellent in 35 cases (61.4%), vascular compromise in 5 cases (8.8%), flap bulkiness in 11 cases (19.3%), callosities and scarring in 2 cases (3.5%), local infection in 1 case (1.8%), and wound dehiscence in 1 case (1.8%). Notably, 2 cases (3.5%) developed complete flap necrosis. Among the anterolateral thigh perforator (ALTP) flaps, there were 4 septocutaneous flaps, 5 flow-through flaps, 1 musculocutaneous flap, 3 chimeric flaps, and 4 cross-leg flaps. All wounded legs exhibited robust dorsalis pedis artery pulsations and optimal blood perfusion to the toes following flap coverage. Patients receiving cross-leg flaps demonstrated optimal distal vascular perfusion in the contralateral lower extremity. One month post-surgery, these flaps showed no apparent signs of ischemia after pedicle division. DISCUSSION Computed Tomography Angiography (CTA) has been extensively employed in the field of flap surgery, serving a purpose akin to handheld Doppler ultrasound, color Doppler, and Magnetic Resonance Angiography (MRA)[ 6 ]. Its primary utility lies in the precise localization and measurement of vascular structures pertaining to a specific flap. In this series, beyond its utility in perforator mapping for flap design, we have discovered that CTA can also be leveraged to precisely evaluate the recipient site. For lower extremity reconstruction, a single CTA examination can comprehensively depict the major arteries below the abdomen and their associated perforating branches. This allows for a thorough assessment of both the recipient and donor site conditions of both lower extremities, enabling the formulation of an optimized reconstructive plan tailored to the specific characteristics of each complex lower leg defect. Typically, we select the descending branch perforator flap of the lateral femoral circumflex artery from both thighs as the donor site and the anterior and posterior tibial arteries of both calves as the recipient vessels for anastomosis. When bilateral anterolateral thigh flaps are unsuitable, we opt for the perforator flap of the inferior epigastric artery as the donor site. Capitalizing on this CTA-derived, high-fidelity anatomic information, our research team has gradually developed a CTA-based, precision reconstruction approach for managing complex lower extremity wounds (Fig. 1). The core principle involves the comprehensive evaluation of the vascular conditions of potential donor sites and recipient sites using CTA data. This helps the selection and design of the most appropriate soft tissue flap for the specific defect. CTA's utility in this context remains unparalleled by other imaging modalities in the realm of flap surgery. Meanwhile, the distinguishing feature of CTA vascular imaging is the enhanced contrast opacification of larger caliber and higher-quality blood vessels, which enables the precise localization of perforator vessels and accurate delineation of their intricate course within the muscular and soft tissue planes[ 8 ]. This advantageous characteristic of CTA is highly beneficial for the targeted selection of reliable perforator vessels to supply the reconstructive flap[ 9 ]. Utilizing the detailed CTA-derived vascular mapping, we are able to readily identify and select suitable perforator vessels to serve as the principal vascular pedicle[ 10 ] In the context of complex lower extremity wounds and fractures, the ability to reliably identify and incorporate dependable recipient site vessels is instrumental in ensuring ease of anastomoses and not to compromise more of the distal perfusion of the leg. The existing medical literature has documented a plethora of flap reconstruction techniques employed in the management of complex lower extremity wounds. However, a paucity of reliable research data and published evidence currently precludes the determination of the most optimal flap modality[ 11 – 13 ]. The primary underlying reason for this knowledge gap can be attributed to the four fundamental challenges inherent to the reconstruction of complex lower leg defects. Firstly, the unique anatomical characteristics of the lower leg region, coupled with the frequently extensive nature of the attendant tissue trauma, often result in wound dimensions, configurations, and depths that exhibit marked heterogeneity, potentially involving concomitant muscle, nerve, and skeletal system involvement[ 14 , 15 ]. Secondly, the compromised condition of the major lower limb vasculature, stemming from either direct vascular injury or prolonged ischemia secondary to contaminated wound environments, poses formidable obstacles to the successful re-establishment of adequate distal perfusion[ 16 ]. Thirdly, the lower extremity is renowned for the extensive anatomical variability encountered in the popliteal artery and its terminal branches, with common developmental abnormalities of the anterior and posterior tibial arteries. These branching pattern variations are not simply complete absence, as described in the Kim classification system, but rather a gradual distal tapering and replacement by the peroneal artery to form the dorsal pedal or plantar arteries. Crucially, all of these popliteal artery branch variations manifest in the distal one-third of the lower leg, necessitating heightened intraoperative awareness during flap procedures in this region [ 17 ][ 18 ]. Fourthly, a substantial body of literature has documented the frequent anatomical variations encountered in the vascular pedicles of various flap donor sites[ 19 – 21 ] These challenges preclude the existence of a universal reconstructive technique capable of comprehensively addressing all complex lower leg defects, and concomitantly render it exceedingly difficult to reliably compare the outcomes of different flap modalities. The case series presented herein substantiates the ubiquitous presence of these formidable challenges, which are challenging to overcome based on clinical experience and intuition alone. Our proposed CTA-guided comprehensive assessment and personalized reconstruction strategy represents a systematic, evidence-based approach to selecting the optimal flap solution tailored to the specific wound characteristics and vascular anatomy of each individual patient. In this study, flap selection primarily involved ALTP and DIEP flaps. When both are suitable, the ALTP flap is preferred due to its comparable thickness to the lower leg recipient site. If both anterolateral thigh flaps are viable, the contralateral side is favored to facilitate tourniquet use and surgical access. Perforator flaps are used for shallow wounds, while musculocutaneous flaps are selected for deeper defects to fill dead space. Wide or irregular wounds are addressed with a single wide perforator flap, a chimeric musculocutaneous flap (with potential donor site skin grafting), or multi-perforator lobed flaps to convert width into length. For crossing flaps requiring subcutaneous anastomosis, flaps with long vascular pedicles are preferred. If pedicle length is insufficient, the posterior tibial vessels may be freed for anastomosis. In some cases, a thin split-thickness skin graft can protect the vascular pedicle (case 2 ). Traditional flap surgery reflects an empirical approach. The surgeon selects the donor site and recipient site mainly based on the characteristics of the wound, then undertakes flap design and harvest. This approach exhibits a notable degree of subjectivity and inherent uncertainty. In contrast, our reconstructive solutions embody a scientific mindset, which is more objective and evidence-based. And as mentioned before, this is more reliable than other preoperative assessment methods like doppler ultrasound etc. The surgeon selects the optimal flap to reconstruct the recipient site based on the objective imaging findings and utilizes quantitative data to guide the flap design and harvesting process. By enabling precise preoperative mapping of recipient vessels, this approach decreases intraoperative patient repositioning, limits unnecessary surgical exploration, and streamlines real-time decision-making, thereby reducing intraoperative delays caused by surgeon uncertainty. However, this cohort represents a single-center experience, with a limited sample size, which may introduce bias in the results. CTA is not a flawless imaging modality. Its visualization of smaller-caliber perforator vessels (particularly those with diameters < 0.5 mm) remains suboptimal, as these vessels often evade detection due to current technical limitations[ 9 ]. Nevertheless, advancements in imaging protocols and contrast agents are expected to enhance the precise delineation of fine vascular anatomy, including the course and morphology of minute perforators. In addition, CTA involves ionizing radiation, which could pose potential risks for pediatric patients and women of childbearing age. The treatment algorithm is based on our circumscribed clinical experience, and its broader applicability may require further validation and refinement. CONCLUSION The integration of computed tomographic angiography (CTA) into preoperative planning enables a comprehensive evaluation of both wound characteristics and recipient vascular anatomy, thereby facilitating optimal donor site selection. This imaging-guided approach allows for the development of individualized, anatomically precise reconstructive strategies, particularly suited to the complex demands of lower extremity defects. By shifting from traditional empirical methods to a scientifically informed, evidence-based paradigm, CTA represents a significant advancement in microsurgical planning. Its application holds considerable promise for improving outcomes in complex lower limb reconstruction, particularly in cases involving extensive soft tissue loss, compromised vascularity, or high-risk patient profiles. Declarations Ethics approval and consent to participate: The study was conducted in accordance with the Declaration of Helsinki, and approved by the Ethics Committee of 920th Hospital of Joint Logistics Support Force of PLA (protocol code 920IEC/AF/61/2013-03.1) Consent for publication: Informed consent was obtained from all subjects involved in the study. Availability of data and materials : Data are available upon request due to restrictions. Conflicts of Interest : The authors declare no conflicts of interest. Funding: This work was financially supported by the National Natural Science Foundation of China (82372381） Author Contributions : Conceptualization, Yueliang Zhu; Methodology, Zhen Shi; Validation, Yongyue Su; Formal Analysis, Sunwen Pan; Investigation, Xi Yang; Resources, Yujian Xu; Data Curation, Sunwen Pan; Writing—original draft preparation, Zhen Shi and Zehui Zhao; Writing—Review and editing, Zhen Shi; Visualization, Sunwen Pan; Supervision, Yueliang Zhu; Project administration, Xiaoqing He; Funding acquisition, Yueliang Zhu. All authors have read and agreed to the published version of the manuscript. Yueliang Zhu and Yongyue Su contributed equally to the research. Acknowledgments: The authors are grateful to the staff of the Department of Surgery, 920th Hospital of Joint Logistics Support Force of PLA References Gupta S, Gupta P, Khichar P, Mohammad A, Escandon JM, Kalra S: Perforator propeller flaps for lower extremity soft-tissue defect reconstruction: Shortening the learning curve. J Clin Orthop Trauma 2022, 27:101831. Li Y, Chen Y, Gan T, Qin B, Liu X, Zhang H: An alternative therapeutic strategy for infected large bone defect and massive soft-tissue loss of leg-is free flap reconstruction inevitable? INT ORTHOP 2021, 45(12):3033–3043. Bibbo C, Nelson J, Fischer JP, Wu LC, Low DW, Mehta S, Kovach SJ, Levin LS: Lower Extremity Limb Salvage After Trauma: Versatility of the Anterolateral Thigh Free Flap. J ORTHOP TRAUMA 2015, 29(12):563–568. Kozusko SD, Liu X, Riccio CA, Chang J, Boyd LC, Kokkalis Z, Konofaos P: Selecting a free flap for soft tissue coverage in lower extremity reconstruction. INJURY 2019, 50 Suppl 5:S32-S39. 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Valdatta L, Tuinder S, Buoro M, Thione A, Faga A, Putz R: Lateral circumflex femoral arterial system and perforators of the anterolateral thigh flap: an anatomic study. Ann Plast Surg 2002, 49(2):145–150. Lakhiani C, Lee MR, Saint-Cyr M: Vascular anatomy of the anterolateral thigh flap: a systematic review. PLAST RECONSTR SURG 2012, 130(6):1254–1268. Angrigiani C, Rancati A, Varela I, Rancati A, Nahabedian MY, Neligan P: The Deltopectoral/Internal Mammary Artery Perforator Flap Revisited: Design Variations Based on Cadaveric and Clinical Investigation. Ann Plast Surg 2022, 88(1):88–92. Cases Cases 1 to 4 are available in the Supplementary Files section Additional Declarations No competing interests reported. Supplementary Files Case1.jpg Case2.jpg Case3.jpg Case4.jpg Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7233679","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":521733372,"identity":"fecf9ab8-3ee7-4aaf-a206-e4d27482c9a2","order_by":0,"name":"Yueliang Zhu","email":"","orcid":"","institution":"Second Affiliated Hospital of Zhejiang University","correspondingAuthor":false,"prefix":"","firstName":"Yueliang","middleName":"","lastName":"Zhu","suffix":""},{"id":521733374,"identity":"c28fad90-fff9-4666-9263-2335ab7099c2","order_by":1,"name":"Yongyue Su","email":"","orcid":"","institution":"920th Hospital of Joint Logistics Support Force 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1","display":"","copyAsset":false,"role":"figure","size":982102,"visible":true,"origin":"","legend":"\u003cp\u003eFlowchart for Evaluating Vascular Conditions and Management Strategies in the Lower Leg Recipient Area\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7233679/v1/caa0a85f5da68e2dadee7d4d.jpg"},{"id":96741759,"identity":"a6f12a5b-93ec-4760-b6bb-02bc5ae53ae5","added_by":"auto","created_at":"2025-11-25 15:08:59","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1485143,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7233679/v1/06c59867-d57e-4a79-9eba-09b4ff62e7ed.pdf"},{"id":92476231,"identity":"fc40f6b8-7237-49f7-9a21-b3de4d49aee3","added_by":"auto","created_at":"2025-09-30 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represents a complicated reconstructive challenge.[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Of various reconstructive interventions, flap transfer, especially free flap, remains a primary method for soft tissue defect reconstruction. Compared with pedicled flaps, free flaps can repair larger sizes of defects, restore well-vascularized soft tissue, and promote osteogenesis[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. However, a seriously injured lower leg is often complicated by concomitant injuries to the major neurovascular structures. The inherent anatomic variability of the vasculature can make the selection of appropriate recipient vessels exceptionally challenging in the surgery. Meanwhile, the donor site anatomy, including the perforator vessels and their vascular pedicles, can be highly variable, further increasing the technical complexity of these reconstructive procedures. Without sufficient information of the vessels related to free flap transfer (donor site and recipient site), the most experienced surgeons[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] struggle to complete free flap transfers efficiently, often resulting in prolonged, exhausting procedures.\u003c/p\u003e\u003cp\u003eThe application of Computed Tomographic Angiography (CTA) technology has been extensively adopted within the field of reconstructive flap surgery. However, its current utilization has been primarily focused on the precise localization and dimensional assessment of the vascular anatomy within a designated flap[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The significance of CTA in evaluating recipient vasculature appears to be underemphasized, reflected by its limited scholarly coverage. The preoperative data pertaining to the recipient site serves not only as a crucial component in the harvesting of free flaps but also as a fundamental element in the amalgamation of information concerning the donor and recipient sites for vascular assessment, correlation, and the formulation of optimal procedural strategies. Research elucidating the amalgamation of these facets for the purpose of flap strategy development is notably scant, suggesting that the integration of these variables may yield substantive value in the strategic planning of flap procedures. Since March 2013, we have applied this CTA-guided, precision flap reconstruction methodology in the clinical management of 57 cases. A retrospective analysis of these patients was conducted, evaluating clinical outcomes based on flap perfusion assessment and other relevant metrics.\u003c/p\u003e"},{"header":"PATIENTS AND METHODS","content":"\u003cp\u003e\u003cem\u003e2.1 Patient Demographics and Injury Characteristics\u003c/em\u003e\u003c/p\u003e\u003cp\u003eOver the 10-year period from March 2013 to October 2023, a total of 57 patients with complex lower extremity soft tissue defects underwent reconstruction using the CTA-guided precision technique. The cohort comprised 43 male and 14 female patients, with an age distribution ranging from 9 to 72 years and a mean age of 44.1 years. The etiologies of injury and the dimensions of the complex soft tissue defects of spanned a wide range (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). In all cases, the reconstructive procedures were performed as delayed, elective interventions following initial wound debridement.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003ePatient demographics (n\u0026thinsp;=\u0026thinsp;57)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNumber\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePatients Gender Distribution:\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e43\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFemale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e14\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eInjury Etiologies:\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMachine-related trauma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMotor vehicle accidents\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCrush injuries from heavy objects\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVarious infectious processes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSharp lacerations\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFalls from standing height\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHigh-energy falls\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eExplosions\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTumors\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBurns\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFlap necrosis following previous reconstructive surgery\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDefect Dimensions(cm*cm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4*8\u0026ndash;55*65\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cem\u003e2.2 Preoperative CTA-based Vascular Mapping Methodology\u003c/em\u003e\u003c/p\u003e\u003cp\u003ePatients were positioned supine with the lower extremities maintained in a neutral, extended alignment. Following intravenous administration of the iodinated contrast agent iohexol (35 g in 100 mL; Yangtze River Pharmaceutical Group, China), continuous CT angiographic imaging was performed from the abdomen to the feet using a 64-slice multidetector CT scanner (GE Healthcare, USA). The CT acquisition parameters were optimized at 120\u0026ndash;140 kV, 525 mA, and a thin slice thickness of 0.625 mm.\u003c/p\u003e\u003cp\u003eThe high-resolution CTA datasets were then reviewed on a picture archiving and communication system (PACS) workstation to meticulously visualize the contrast-enhanced vasculature and identify the most suitable recipient vessels for the planned reconstructive procedure. The precise localization of the vessels and associated perforating branches was determined in reference to reliable bony landmarks using the following techniques:\u003c/p\u003e\u003cp\u003eA:The longitudinal distance between the vessel/perforator and the bony landmark was calculated by measuring the difference in CT slice numbers between the two structures and multiplying by the isotropic slice thickness.\u003c/p\u003e\u003cp\u003eB:The transverse distance between the bony landmark and the vessel/perforator was quantified on the PACS system by positioning the cursor on the bony landmark, maintaining the cursor position, scrolling to the plane of the vessel/perforator, and directly measuring the distance between the cursor and the vascular structure.\u003c/p\u003e\u003cp\u003eThis comprehensive CTA-based vascular mapping approach allowed for meticulous preoperative planning and localization of the key vascular anatomy, thereby facilitating the precision of the subsequent reconstructive intervention.\u003c/p\u003e\u003cp\u003e\u003cem\u003e2.3 Recipient Vessel Selection\u003c/em\u003e\u003c/p\u003e\u003cp\u003eThe selection of appropriate recipient vessels is a critical step in preoperative planning for reconstructive procedures. The fundamental requirements for recipient vessel selection is the adequate visualization and opacification of the proximal recipient vessels on CTA. This ensures the patency and suitability of the vessels for microsurgical anastomosis. The sacrifice of the selected recipient vessels should not influence the distal perfusion of the affected limb. Maintaining adequate distal blood flow is paramount to prevent ischemic complications.\u003c/p\u003e\u003cp\u003eThe selected recipient vessels should be located outside of any zones of active inflammation or infection. The surrounding soft tissue and bony anatomy should be clearly delineated to facilitate the surgical dissection and anastomosis. When selecting the recipient vessels, the following priority factors should be considered:\u003c/p\u003e\u003cp\u003e1. Prioritizing the proximal end. We prioritize the proximal end for anastomosis by selecting the nearby artery and vein, as this facilitates the procedure and aligns blood flow with the recipient area. Although distal anastomosis is feasible, it would involve reversed flow in both the artery and vein.\u003cins cite=\"mailto:Microsoft%20Office%20User\" datetime=\"2025-05-16T09:34\"\u003e\u0026nbsp;\u003c/ins\u003e\u003c/p\u003e\n\u003cp\u003e2. Vessels located in close proximity to the wound. This would facilitate a tension-free anastomosis and minimize the length of the vascular pedicle.\u003c/p\u003e\n\u003cp\u003e3. Vessels with ease of exposure and accessibility. These vessels are readily identifiable and can be safely dissected to minimize surgical complexity and operative time.\u003c/p\u003e\n\u003cp\u003eThe specific recipient vessel selection should be tailored to the individual clinical scenario.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAfter selecting the recipient vessels, the surgeon should meticulously document the distance between the vessels and the wound site, as well as the spatial relationship between the recipient\u0026nbsp;\u003c/p\u003e\n\u003cp\u003evessels and the surrounding anatomical landmarks. This comprehensive preoperative vascular mapping is essential to ensure the precision and success of the reconstructive procedure.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e2.4 Donor Flap Selection\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eBased on the characteristics of the recipient vessels, as determined by computed tomographic angiography (CTA), the most commonly utilized donor flap options for lower extremity reconstruction is the anterolateral thigh perforator (ALTP) flap and the deep inferior epigastric perforator (DIEP) flap.\u0026nbsp;When both ALTP and DIEP flaps meet the requisite criteria simultaneously, ALTP is prioritized owing to its similar flap thickness and characteristics. In scenarios where bilateral ALTP flaps satisfy the criteria, preference is given to the contralateral side due to the benefits conferred by tourniquet application and enhanced surgical maneuverability.\u003c/p\u003e\n\u003cp\u003eThe primary considerations in donor flap selection are: the Presence of reliable perforator vessels to adequately vascularize the flap. Adequate length and caliber of the vascular pedicle to reach and appropriately perfuse the recipient vessels. In scenarios where there exists a surplus of donor sites meeting the fundamental prerequisites for the flap, the determination of the flap type and selection of the donor site are predicated upon an assessment of the wound\u0026apos;s depth and morphology. In instances of profound wound depth, conventional perforator flaps may prove inadequate for effective coverage, at this point, a muscle-containing myocutaneous flap can be selected to cover deeper soft tissue defects and obliterate dead space. For the broader or irregularly shaped wounds, wider single-perforator flaps may be preferable. Alternatively, the utilization of lobulated perforator flaps to construct a customized composite structure tailored for comprehensive wound coverage is warranted.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFor cross-leg flap reconstruction, given that the anastomosis site must be in the subcutaneous plane and the distance between the two crossed legs, the preferred option is to select a flap with an adequately long vascular pedicle. If the pedicle length of the chosen flap is insufficient, it becomes necessary to microsurgically harvest and transpose the posterior tibial artery and vein up to the recipient site for the microvascular anastomosis. In the region surrounding the exposed vascular pedicle of the cross-leg flap, the defect can be appropriately resurfaced utilizing thick split-thickness skin grafting [7].\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e2.5 Surgical Planning and Execution\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eAt the donor site, the locations of the perforating vessels are plotted using a Cartesian coordinate system, delineating their positions along the horizontal and vertical axes. Based on the documented course of the vascular pedicle and the surrounding anatomical structures, a schematic diagram is meticulously created to illustrate the perforator locations and the detailed pedicle anatomy, with clear markings of important landmark structures. An analogous approach is employed to precisely map the positions of the recipient vessels.\u003c/p\u003e\n\u003cp\u003eGuided by the principles of CTA-guided free flap design, the free flap harvest is typically performed in an antegrade fashion, as the perforator locations, pedicle length, and the intricate spatial relationships with the surrounding tissues have been thoroughly evaluated and accurately marked during the preoperative planning stage. This technique effectively mitigates the technical complexity of the dissection and facilitates a reduction in the overall operative duration, as it circumvents the need for time-consuming retrograde perforator identification. The DIEP flaps were meticulously crafted in polyfoliate configurations to optimize aesthetic outcomes, with the option of employing micro-thinning techniques when deemed necessary.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e2.6\u0026nbsp;\u003c/em\u003e\u003cem\u003ePostoperative Care and Monitoring\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eIn the postoperative period, the patient is managed in accordance with the standard protocols established for microsurgical reconstructive procedures. Measures are implemented to maintain normothermia and regulate the ambient temperature, while routine antimicrobial prophylaxis is administered to mitigate the risk of infectious complications. During the initial 72-hour postoperative period, the vascular status of the transferred flap is meticulously evaluated at 2-hourly intervals; this frequency is subsequently reduced to every 6 hours for the ensuing 72-hour period.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn the event of any compromise in the vascular perfusion of the flap, prompt surgical exploration and timely intervention are undertaken to address the underlying etiology. The affected extremity is immobilized (usually by external fixation) for a period of 1-2 weeks in the postoperative phase to prevent traction on the vascular pedicle and to mitigate the risk of spasm.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e2.7 Evaluation Criteria for Flap Blood Perfusion\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe assessment criteria for flap blood perfusion are delineated based on the guidelines for assessing finger replantation function as established by the Hand Surgery Division of the Chinese Medical Association. These standards gauge the vascular status of the flap through considerations encompassing skin coloration, temperature, and cold intolerance. Excellent: Manifesting normal skin color and temperature, devoid of the necessity for specialized protective measures; Good: Exhibiting a marginal deviation in skin coloration, coupled with a slightly diminished temperature and sensitivity to cold stimuli; Fair: Presenting with pallor or cyanosis in skin hue, along with a notable decline in temperature and heightened susceptibility to cold conditions; Poor: Featuring a dusky or cyanotic skin appearance, with a marked aversion to exposure in chilly environments.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003eIn this series, flap sizes ranged from 5cm \u0026times; 10 cm to 55 cm \u0026times; 70 cm, with 52 cases of free anterolateral thigh perforator (ALTP) flaps and 5 cases of free deep inferior epigastric perforator (DIEP) flaps (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Complete flap survival was achieved in 54 cases, with 1 case demonstrating partial flap necrosis that required a repeat flap procedure resulting in successful salvage, and 2 cases of total flap loss (3.5%).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eBasic Clinical Data of Flap Design in Patients (n\u0026thinsp;=\u0026thinsp;57)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNumber\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFlap Sizes (cm*cm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5*10\u0026ndash;55*70\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFlap Types\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAnterolateral thigh perforator (ALTP) flaps\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e52\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTypical free flap\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e35\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSeptocutaneous flaps\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFlow-through flaps\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMusculocutaneous flaps\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eChimeric flaps\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCross-leg flaps\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDeep inferior epigastric perforator (DIEP) flaps\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFlap Survival:\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e57\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eComplete survival\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e54\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePartial necrosis requiring repeat procedure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal flap loss\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe microsurgical harvest of all flaps was accomplished in a meticulous and precise manner. Regarding donor site management, the preoperative CTA assessment of the recipient vascular origins, course direction, overall length, anastomosis sites, and vascular endpoints was found to be in complete agreement with the intraoperative anatomical findings, yielding a concordance rate of 100%. Primary closure was performed in 52 cases, while partial closure with subsequent skin grafting was undertaken in 4 cases, and secondary skin grafting after partial donor site necrosis in 1 case.\u003c/p\u003e\u003cp\u003eAccording to the assessment of the recipient vessels in the leg of our results, the recipient vessels in the lower leg can exhibit 3 different types of presentation on CTA imaging due to factors such as trauma, anatomical variations, and the impact of internal/external fixation (Figure 1):\u003c/p\u003e\u003cp\u003eA: The two main arterial trunks in the affected lower leg are continuous and take one arterial system as the recipient vessels would not compromise the distal perfusion.\u003c/p\u003e\u003cp\u003eB: One of the main arterial trunks in the affected lower leg is continuous, while the other is unreliable. Taking this continuous vessel may potentially impair the distal perfusion of the leg. Consequently, the unreliable vessel stump may be selected as the recipient site (Type B1). If the stump is severely damaged and deemed unsuitable as a recipient site, the healthy posterior tibial artery of the contralateral side can be chosen instead (Type B2). In the absence of a healthy posterior tibial artery, an artery with a longer healthy vascular pedicle (medial or lateral sural artery) should be selected as the recipient site (Type B3). When considering the medial and lateral sural arteries as recipient vessels, it is essential to have a sufficiently long vascular pedicle of the flap for the cross-leg anastomosis; thus, the length of the donor area vessels must be carefully assessed prior to making a definitive decision.\u003c/p\u003e\u003cp\u003eC: Both arterial trunks in the affected lower leg are unreliable and taking either one as recipient vessels may affect the distal perfusion. In this case, we would use flow-through flap technique.\u003c/p\u003e\u003cp\u003eTypes B and C are commonly observed in cases of comminuted tibial-fibular fractures, where internal/external fixation can lead to compression, distortion, or discontinuity of the main arterial trunks as observed on the CTA cross-sections. This comprehensive CTA-based assessment of the leg vascular anatomy is crucial for preoperative planning to ensure adequate distal perfusion is maintained during and after the reconstructive procedure. The typical cases of type A, B and C are illustrated in cases 1, \u003cspan refid=\"FPar3\" class=\"InternalRef\"\u003e2\u003c/span\u003e, \u003cspan refid=\"FPar4\" class=\"InternalRef\"\u003e3\u003c/span\u003e, and \u003cspan refid=\"FPar5\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eTypical cases:\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eCase1\u003c/strong\u003e\u003cp\u003eA: A 52-year-old male patient with an open fracture of the right lower leg, the wound size was 18cm\u0026times;8cm, the internal fixation of plates and screws had been performed at the fracture site; B: Preoperative CTA outcomes (from anterior view); C: CTA imaging clearly delineates the anatomical course of the anterior tibial artery (ATA), posterior tibial artery (PTA), and fibular artery (FA) at the recipient site (right lower extremity), marked by black arrows, along with the morphology of the vascular stumps, indicated by red arrows. Digital reconstruction of the recipient site revealed continuity of only one group of main blood vessels, while the remnants of another vessel group were deemed viable, indicative of Type B1 collateral availability; D: Preoperative assessment via CTA identified several potential donor sites, with the left thigh meeting the necessary criteria for identifying a perforator and designing a flap; E: The left anterior lateral thigh flap was harvested precisely according to the preoperative plan; F: An anastomosis was established with the posterior tibial artery in the recipient area. The fractures were fixed with external fixation; G: One week postoperatively, the flap exhibited favorable shape and coloration.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eCase 2\u003c/strong\u003e\u003cp\u003eA: A 53-year-old male patient with an open fracture of the left lower leg, the wound size was 7cm\u0026times;7cm and the fractures were fixed with external fixation; B: Preoperative CTA outcomes (from posterior view); C: CTA imaging revealed the remnants of another vessel group (the anterior tibial vessels) were nonviable. However, the contralateral leg has an intact posterior tibial artery. Digital reconstruction assessment of the recipient site revealed continuity of only one group of main blood vessels(the posterior tibial vessels), the situation is consistent with Type B2 where the contralateral posterior tibial artery is present; D: Preoperative CTA-guided identification of a perforator in the donor site showed that the perforator pedicle of the right anterior lateral thigh flap was long enough for the design of a crossover flap; E: The intraoperative findings during flap harvesting revealed that the course and length of the vascular pedicle were completely consistent with the preoperative CTA examination; F: Vessels anastomosis was performed with the contralateral posterior tibial artery, the exposed vessel pedicle of the flap between the legs were skin-grafted; G: At one-month post-surgery, pedicle division was carried out, and the flap demonstrated successful survival.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eCase 3\u003c/strong\u003e\u003cp\u003eA: A 45-year-old female with open fracture of the left lower leg, the wound size was 40cm\u0026times;15cm and the fractures were fixed with external fixation; B: Preoperative CTA outcomes (from posterior view); C: CTA assessment of the recipient site revealed continuity of only one group of main blood vessels(the anterior tibial artery)in the left lower leg, with the remnants of another vessel group being unreliable for anastomosis. Meanwhile, the contralateral posterior tibial artery was absent, only had anterior tibial artery and peroneal artery (Type B3), which means the vessels of the contralateral leg were not suitable for anastomosis to the flap vessel pedicle; D: Preoperative CTA identified left ALTP flap had a long vessel pedicle of the intermuscular septal perforators, which matched the need of recipient site vessels\u0026rsquo; anastomosi. Therefore, the left thigh was chosen as the donor site for the ALTP flap. E: The intraoperative findings were completely consistent with the preoperative CTA assessment. The flap had a long vessel pedicle; F: Anastomosis was performed with the medial sural artery; G: At a 5-month postoperative follow-up, the flap demonstrated successful survival.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eCase 4\u003c/strong\u003e\u003cp\u003eA: A 53-year-old female sustained an open fracture of the right leg, the wound size was 20cm\u0026times;15cm; B: Preoperative CTA outcomes (from anterior view); C: Preoperative CTA assessment of the recipient site indicated that neither group of blood vessels on the affected leg was continuous, consistent with Type C classification (red arrow); D : A flow-through ALTP flap was used to finish the wound coverage and restore the distal circulation, the fractures were fixed with external fixation; E: At one week postoperatively, the flap showed good survival.\u003c/p\u003e\u003c/p\u003e\u003cp\u003eA follow-up period of 3 to 50 months was conducted for the cohort of 57 patients, during which the color, contour, and tissue quality of the transferred flaps were evaluated and deemed satisfactory. Clinical outcomes were categorized as follows: excellent in 35 cases (61.4%), vascular compromise in 5 cases (8.8%), flap bulkiness in 11 cases (19.3%), callosities and scarring in 2 cases (3.5%), local infection in 1 case (1.8%), and wound dehiscence in 1 case (1.8%). Notably, 2 cases (3.5%) developed complete flap necrosis. Among the anterolateral thigh perforator (ALTP) flaps, there were 4 septocutaneous flaps, 5 flow-through flaps, 1 musculocutaneous flap, 3 chimeric flaps, and 4 cross-leg flaps. All wounded legs exhibited robust dorsalis pedis artery pulsations and optimal blood perfusion to the toes following flap coverage. Patients receiving cross-leg flaps demonstrated optimal distal vascular perfusion in the contralateral lower extremity. One month post-surgery, these flaps showed no apparent signs of ischemia after pedicle division.\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eComputed Tomography Angiography (CTA) has been extensively employed in the field of flap surgery, serving a purpose akin to handheld Doppler ultrasound, color Doppler, and Magnetic Resonance Angiography (MRA)[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Its primary utility lies in the precise localization and measurement of vascular structures pertaining to a specific flap. In this series, beyond its utility in perforator mapping for flap design, we have discovered that CTA can also be leveraged to precisely evaluate the recipient site. For lower extremity reconstruction, a single CTA examination can comprehensively depict the major arteries below the abdomen and their associated perforating branches. This allows for a thorough assessment of both the recipient and donor site conditions of both lower extremities, enabling the formulation of an optimized reconstructive plan tailored to the specific characteristics of each complex lower leg defect. Typically, we select the descending branch perforator flap of the lateral femoral circumflex artery from both thighs as the donor site and the anterior and posterior tibial arteries of both calves as the recipient vessels for anastomosis. When bilateral anterolateral thigh flaps are unsuitable, we opt for the perforator flap of the inferior epigastric artery as the donor site. Capitalizing on this CTA-derived, high-fidelity anatomic information, our research team has gradually developed a CTA-based, precision reconstruction approach for managing complex lower extremity wounds (Fig.\u0026nbsp;1). The core principle involves the comprehensive evaluation of the vascular conditions of potential donor sites and recipient sites using CTA data. This helps the selection and design of the most appropriate soft tissue flap for the specific defect. CTA's utility in this context remains unparalleled by other imaging modalities in the realm of flap surgery. Meanwhile, the distinguishing feature of CTA vascular imaging is the enhanced contrast opacification of larger caliber and higher-quality blood vessels, which enables the precise localization of perforator vessels and accurate delineation of their intricate course within the muscular and soft tissue planes[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. This advantageous characteristic of CTA is highly beneficial for the targeted selection of reliable perforator vessels to supply the reconstructive flap[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Utilizing the detailed CTA-derived vascular mapping, we are able to readily identify and select suitable perforator vessels to serve as the principal vascular pedicle[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] In the context of complex lower extremity wounds and fractures, the ability to reliably identify and incorporate dependable recipient site vessels is instrumental in ensuring ease of anastomoses and not to compromise more of the distal perfusion of the leg.\u003c/p\u003e\u003cp\u003eThe existing medical literature has documented a plethora of flap reconstruction techniques employed in the management of complex lower extremity wounds. However, a paucity of reliable research data and published evidence currently precludes the determination of the most optimal flap modality[\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. The primary underlying reason for this knowledge gap can be attributed to the four fundamental challenges inherent to the reconstruction of complex lower leg defects. Firstly, the unique anatomical characteristics of the lower leg region, coupled with the frequently extensive nature of the attendant tissue trauma, often result in wound dimensions, configurations, and depths that exhibit marked heterogeneity, potentially involving concomitant muscle, nerve, and skeletal system involvement[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Secondly, the compromised condition of the major lower limb vasculature, stemming from either direct vascular injury or prolonged ischemia secondary to contaminated wound environments, poses formidable obstacles to the successful re-establishment of adequate distal perfusion[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Thirdly, the lower extremity is renowned for the extensive anatomical variability encountered in the popliteal artery and its terminal branches, with common developmental abnormalities of the anterior and posterior tibial arteries. These branching pattern variations are not simply complete absence, as described in the Kim classification system, but rather a gradual distal tapering and replacement by the peroneal artery to form the dorsal pedal or plantar arteries. Crucially, all of these popliteal artery branch variations manifest in the distal one-third of the lower leg, necessitating heightened intraoperative awareness during flap procedures in this region [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e][\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Fourthly, a substantial body of literature has documented the frequent anatomical variations encountered in the vascular pedicles of various flap donor sites[\u003cspan additionalcitationids=\"CR20\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] These challenges preclude the existence of a universal reconstructive technique capable of comprehensively addressing all complex lower leg defects, and concomitantly render it exceedingly difficult to reliably compare the outcomes of different flap modalities. The case series presented herein substantiates the ubiquitous presence of these formidable challenges, which are challenging to overcome based on clinical experience and intuition alone. Our proposed CTA-guided comprehensive assessment and personalized reconstruction strategy represents a systematic, evidence-based approach to selecting the optimal flap solution tailored to the specific wound characteristics and vascular anatomy of each individual patient.\u003c/p\u003e\u003cp\u003eIn this study, flap selection primarily involved ALTP and DIEP flaps. When both are suitable, the ALTP flap is preferred due to its comparable thickness to the lower leg recipient site. If both anterolateral thigh flaps are viable, the contralateral side is favored to facilitate tourniquet use and surgical access. Perforator flaps are used for shallow wounds, while musculocutaneous flaps are selected for deeper defects to fill dead space. Wide or irregular wounds are addressed with a single wide perforator flap, a chimeric musculocutaneous flap (with potential donor site skin grafting), or multi-perforator lobed flaps to convert width into length. For crossing flaps requiring subcutaneous anastomosis, flaps with long vascular pedicles are preferred. If pedicle length is insufficient, the posterior tibial vessels may be freed for anastomosis. In some cases, a thin split-thickness skin graft can protect the vascular pedicle (case \u003cspan refid=\"FPar3\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eTraditional flap surgery reflects an empirical approach. The surgeon selects the donor site and recipient site mainly based on the characteristics of the wound, then undertakes flap design and harvest. This approach exhibits a notable degree of subjectivity and inherent uncertainty. In contrast, our reconstructive solutions embody a scientific mindset, which is more objective and evidence-based. And as mentioned before, this is more reliable than other preoperative assessment methods like doppler ultrasound etc. The surgeon selects the optimal flap to reconstruct the recipient site based on the objective imaging findings and utilizes quantitative data to guide the flap design and harvesting process. By enabling precise preoperative mapping of recipient vessels, this approach decreases intraoperative patient repositioning, limits unnecessary surgical exploration, and streamlines real-time decision-making, thereby reducing intraoperative delays caused by surgeon uncertainty.\u003c/p\u003e\u003cp\u003eHowever, this cohort represents a single-center experience, with a limited sample size, which may introduce bias in the results. CTA is not a flawless imaging modality. Its visualization of smaller-caliber perforator vessels (particularly those with diameters\u0026thinsp;\u0026lt;\u0026thinsp;0.5 mm) remains suboptimal, as these vessels often evade detection due to current technical limitations[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Nevertheless, advancements in imaging protocols and contrast agents are expected to enhance the precise delineation of fine vascular anatomy, including the course and morphology of minute perforators. In addition, CTA involves ionizing radiation, which could pose potential risks for pediatric patients and women of childbearing age. The treatment algorithm is based on our circumscribed clinical experience, and its broader applicability may require further validation and refinement.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eThe integration of computed tomographic angiography (CTA) into preoperative planning enables a comprehensive evaluation of both wound characteristics and recipient vascular anatomy, thereby facilitating optimal donor site selection. This imaging-guided approach allows for the development of individualized, anatomically precise reconstructive strategies, particularly suited to the complex demands of lower extremity defects. By shifting from traditional empirical methods to a scientifically informed, evidence-based paradigm, CTA represents a significant advancement in microsurgical planning. Its application holds considerable promise for improving outcomes in complex lower limb reconstruction, particularly in cases involving extensive soft tissue loss, compromised vascularity, or high-risk patient profiles.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u0026nbsp;\u003c/strong\u003eThe study was conducted in accordance with the Declaration of Helsinki, and approved by the Ethics Committee of 920th Hospital of Joint Logistics Support Force of PLA (protocol code 920IEC/AF/61/2013-03.1)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication:\u0026nbsp;\u003c/strong\u003eInformed consent was obtained from all subjects involved in the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e: Data are available upon request due to restrictions.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of Interest\u003c/strong\u003e: The authors declare no conflicts of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u0026nbsp;\u003c/strong\u003eThis work was financially supported by the National Natural Science Foundation of China (82372381）\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e: Conceptualization, Yueliang Zhu; Methodology, Zhen Shi; Validation, Yongyue Su; Formal Analysis, Sunwen Pan; Investigation, Xi Yang; Resources, Yujian Xu; Data Curation, Sunwen Pan; Writing\u0026mdash;original draft preparation, Zhen Shi and Zehui Zhao; Writing\u0026mdash;Review and editing, Zhen Shi; Visualization, Sunwen Pan; Supervision, Yueliang Zhu; Project administration, Xiaoqing He; Funding acquisition, Yueliang Zhu. All authors have read and agreed to the published version of the manuscript. Yueliang Zhu and Yongyue Su contributed equally to the research.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments:\u003c/strong\u003e The authors are grateful to the staff of the Department of Surgery, 920th Hospital of Joint Logistics Support Force of PLA\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGupta S, Gupta P, Khichar P, Mohammad A, Escandon JM, Kalra S: Perforator propeller flaps for lower extremity soft-tissue defect reconstruction: Shortening the learning curve. \u003cem\u003eJ Clin Orthop Trauma\u003c/em\u003e 2022, 27:101831.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi Y, Chen Y, Gan T, Qin B, Liu X, Zhang H: An alternative therapeutic strategy for infected large bone defect and massive soft-tissue loss of leg-is free flap reconstruction inevitable? \u003cem\u003eINT ORTHOP\u003c/em\u003e 2021, 45(12):3033\u0026ndash;3043.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBibbo C, Nelson J, Fischer JP, Wu LC, Low DW, Mehta S, Kovach SJ, Levin LS: Lower Extremity Limb Salvage After Trauma: Versatility of the Anterolateral Thigh Free Flap. \u003cem\u003eJ ORTHOP TRAUMA\u003c/em\u003e 2015, 29(12):563\u0026ndash;568.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKozusko SD, Liu X, Riccio CA, Chang J, Boyd LC, Kokkalis Z, Konofaos P: Selecting a free flap for soft tissue coverage in lower extremity reconstruction. \u003cem\u003eINJURY\u003c/em\u003e 2019, 50 Suppl 5:S32-S39.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLiu H, Liu J, Wu Y, Ma Y, Zhou M, Xue Y, Rui Y: Analysis of the Risk Factors for Free Flap Necrosis in Soft Tissue Reconstruction of the Lower Limbs. \u003cem\u003eORTHOP SURG\u003c/em\u003e 2023, 15(6):1534\u0026ndash;1540.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLange CJ, Thimmappa ND, Boddu SR, Dutruel SP, Pei M, Farooq Z, Heshmatzadeh BA, Wang Y, Zabih R, Prince MR: Automating Perforator Flap MRA and CTA Reporting. \u003cem\u003eJ DIGIT IMAGING\u003c/em\u003e 2017, 30(3):350\u0026ndash;357.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhang GL, Zhen P, Chen KM, Zhao LX, Yang JL, Zhou JH, Xue QY: [Application of cross-leg soleus muscle flap transplantation to treat the soft-tissue defect in contralateral leg]. \u003cem\u003eZhongguo Gu Shang\u003c/em\u003e 2015, 28(11):1052\u0026ndash;1055.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRosson GD, Holton LH, Silverman RP, Singh NK, Nahabedian MY: Internal mammary perforators: a cadaver study. \u003cem\u003eJ RECONSTR MICROSURG\u003c/em\u003e 2005, 21(4):239\u0026ndash;242.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChen SY, Lin WC, Deng SC, Chang SC, Fu JP, Dai NT, Chen SL, Chen TM, Chen SG: Assessment of the perforators of anterolateral thigh flaps using 64-section multidetector computed tomographic angiography in head and neck cancer reconstruction. \u003cem\u003eEur J Surg Oncol\u003c/em\u003e 2010, 36(10):1004\u0026ndash;1011.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePeng W, Lu C, Zhou B, Song D, Li Z: [Application and prospect of preoperative computed tomographic angiography in deep inferior epigastric artery perforator flap for breast reconstruction]. \u003cem\u003eZhongguo Xiu Fu Chong Jian Wai Ke Za Zhi\u003c/em\u003e 2020, 34(7):927\u0026ndash;931.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLee ZH, Daar DA, Stranix JT, Anzai L, Levine JP, Saadeh PB, Thanik VD: Free-Flap Reconstruction for Diabetic Lower Extremity Limb Salvage. \u003cem\u003eJ SURG RES\u003c/em\u003e 2020, 248:165\u0026ndash;170.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003evon Glinski M, Wallner C, Wagner JM, Dadras M, Sogorski A, Drysch M, Reinkemeier F, Voigt M, Lehnhardt M, Behr B: Free-flap reconstruction of the lower limb in octogenarians - A comparative analysis of indications, management, and outcomes. \u003cem\u003eJ Plast Reconstr Aesthet Surg\u003c/em\u003e 2023, 76:230\u0026ndash;237.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYim GH, Pikturnaite J, Harry L, Clement R, Pope-Jones S, Emam A, Marsden N: Enhanced recovery for acute open lower limb fracture 'fix and flap'. \u003cem\u003eINJURY\u003c/em\u003e 2024, 55(2):111234.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLee ZH, Daar DA, Stranix JT, Anzai L, Levine JP, Saadeh PB, Thanik VD: Free-Flap Reconstruction for Diabetic Lower Extremity Limb Salvage. \u003cem\u003eJ SURG RES\u003c/em\u003e 2020, 248:165\u0026ndash;170.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHiggins TF, Klatt JB, Beals TC: Lower Extremity Assessment Project (LEAP)--the best available evidence on limb-threatening lower extremity trauma. \u003cem\u003eOrthop Clin North Am\u003c/em\u003e 2010, 41(2):233\u0026ndash;239.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYu L, Deng L, Zhu S, Deng K, Yu G, Zhu C, Qi B, Pan Z: Limb-Salvage Outcomes of Arterial Repair Beyond Time Limit at Different Lower-Extremity Injury Sites. \u003cem\u003eMed Sci Monit\u003c/em\u003e 2021, 27:e927652.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSlaba S, Abi KS, Younan T, Nassar-Slaba J, Khoury S, Kheir C: [Unusual variation of popliteal arterial branches: 4 axes by early division of the peroneal artery]. \u003cem\u003eJ Mal Vasc\u003c/em\u003e 2007, 32(4\u0026ndash;5):212\u0026ndash;215.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSaadeh FA, El-Karagy SA, Haikal FA: Anterior tibial artery: variation in origin and branching. \u003cem\u003eSURG RADIOL ANAT\u003c/em\u003e 1995, 17(1):83\u0026ndash;84.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eValdatta L, Tuinder S, Buoro M, Thione A, Faga A, Putz R: Lateral circumflex femoral arterial system and perforators of the anterolateral thigh flap: an anatomic study. \u003cem\u003eAnn Plast Surg\u003c/em\u003e 2002, 49(2):145\u0026ndash;150.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLakhiani C, Lee MR, Saint-Cyr M: Vascular anatomy of the anterolateral thigh flap: a systematic review. \u003cem\u003ePLAST RECONSTR SURG\u003c/em\u003e 2012, 130(6):1254\u0026ndash;1268.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAngrigiani C, Rancati A, Varela I, Rancati A, Nahabedian MY, Neligan P: The Deltopectoral/Internal Mammary Artery Perforator Flap Revisited: Design Variations Based on Cadaveric and Clinical Investigation. \u003cem\u003eAnn Plast Surg\u003c/em\u003e 2022, 88(1):88\u0026ndash;92.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Cases","content":"\u003cp\u003eCases 1 to 4 are available in the Supplementary Files section\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Computed Tomographic Angiography, Perforator Flaps, Lower Extremity Reconstruction, Lower Leg Wounds","lastPublishedDoi":"10.21203/rs.3.rs-7233679/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7233679/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eReconstruction of complex lower leg wounds presents significant challenges due to extensive soft tissue damage, vascular variations, and potential neurovascular injuries. While flap transfer, particularly free flaps, remains the preferred method for reconstruction, the lack of precise preoperative vascular information often complicates surgical planning. This study introduces a Computed Tomographic Angiography (CTA)-guided approach for precision reconstruction to address these challenges.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eFrom March 2013 to October 2023, 57 patients with complex lower leg defects underwent reconstruction using CTA-guided flap surgery. Patient demographics, injury characteristics, and surgical outcomes were retrospectively analyzed. Preoperative CTA was employed to map donor and recipient vascular anatomy, evaluate perforator vessels, and guide flap selection and design. Flap options included anterolateral thigh perforator (ALTP) and deep inferior epigastric perforator (DIEP) flaps, with selection tailored to wound dimensions, depth, and vascular conditions.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eFlap sizes ranged from 5\u0026times;10 cm to 55\u0026times;70 cm, 54 flaps survived completely (94.7%), one partial necrosis requiring revision (1.8%), and two total flap losses (3.5%). CTA demonstrated 100% concordance with intraoperative vascular findings, enabling precise recipient vessel localization and enhanced surgical efficiency. Postoperative complications included vascular compromise (8.8%), flap bulkiness (19.3%), and minimal wound dehiscence (1.8%). Functional and aesthetic outcomes were rated as excellent in 61.4% of cases.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eThe CTA-guided reconstruction approach enables comprehensive preoperative vascular assessment, optimizing donor flap selection and recipient vessel anastomosis. This evidence-based method significantly improves surgical precision and outcomes, representing an advancement over traditional empirical techniques in managing complex lower leg wounds.\u003c/p\u003e","manuscriptTitle":"Computed Tomographic Angiography (CTA)-Guided Precision Reconstruction in Complex Lower Leg Wounds","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-30 07:20:16","doi":"10.21203/rs.3.rs-7233679/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9df4f1ed-a616-437e-b9a0-c6ab17d36fb5","owner":[],"postedDate":"September 30th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-25T15:08:49+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-30 07:20:16","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7233679","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7233679","identity":"rs-7233679","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}