Search Results (46)

Background and Clinical Significance: Choanal atresia is a rare congenital obstruction of the posterior nasal aperture, with an estimated incidence of one in 5000 to one in 8000 live births. Bilateral disease typically presents as a neonatal emergency, whereas unilateral disease is more frequent and may remain undiagnosed for years or decades, presenting in adolescence or adulthood with chronic unilateral nasal obstruction and ipsilateral mucopurulent rhinorrhoea. Optimal surgical management remains debated, particularly with regard to mucosal-flap reconstruction and the choice of postoperative stent. Case Presentation: A 22-year-old male was referred for chronic left-sided nasal obstruction, persistent ipsilateral mucopurulent rhinorrhoea and reduced ipsilateral olfaction. Nasal endoscopy and high-resolution computed tomography demonstrated an isolated, non-syndromic, mixed bony–membranous left choanal atresia. The patient underwent transnasal endoscopic choanoplasty with posterior septectomy and removal of the atretic plate and posterior vomer. An ipsilateral superiorly based septal mucoperichondrial flap was raised first and later transposed over the sphenoid rostrum; following drilling, the contralateral septal mucosa was approached and incised horizontally to generate a superior and an inferior leaflet, which were rotated to cover the corresponding portions of the residual posterior septal ridge. A bioabsorbable mometasone-furoate-eluting sinus implant (PROPEL^®, Medtronic) was deployed across the neo-choana. The follow-up endoscopy at two months demonstrated a widely patent, well-mucosalized neo-choana with complete resolution of symptoms. Conclusions: Transnasal endoscopic posterior septectomy combined with mucosal-flap reconstruction and a bioabsorbable steroid-eluting stent is a technically feasible and biologically rational approach to adult unilateral CA. To our knowledge, this is among the first reports describing the off-label intraoperative use of a PROPEL^® stent in a young adult with isolated unilateral choanal atresia. Full article

Background: The latissimus dorsi free flap is a workhorse for extensive lower-extremity soft tissue defects. Conventionally, the skin paddle is designed according to the anticipated defect and left in place on the muscle as a single composite unit. This report describes an alternative approach in which the skin paddle is secondarily mobilized through subcutaneous undermining and rotated as a separate propeller-type local extension flap on random-pattern vascularization, without a specifically identified perforator—a technique that has not been previously reported. Case Presentation: A 38-year-old male with a high-energy distal lower-extremity defect exposing bone, Achilles tendon, and hardware underwent free latissimus dorsi reconstruction with an empirically designed skin paddle over the constant perforator zone. The skin paddle was subsequently mobilized and rotated as a separate propeller-type extension flap to cover the Achilles region, with additional areas managed using split-thickness skin graft and a reverse soleus flap. Results: The latissimus dorsi flap and skin paddle remained viable, providing stable coverage of the defect. The additional reverse soleus flap achieved durable medial coverage, and the limb was ultimately preserved with satisfactory soft-tissue stability. Conclusion: A random-pattern latissimus dorsi skin paddle designed within the anatomically constant perforator zone can provide a feasible new option offering intraoperative flexibility in complex lower-extremity trauma when perforator mapping is impractical. Full article

Extremity soft tissue sarcoma resection often results in complex defects requiring reconstruction to preserve function and support multidisciplinary treatment. Propeller flaps have emerged as a local alternative to free flaps in selected cases, but their role in sarcoma reconstruction remains incompletely defined. This systematic review aimed to assess the current evidence on the indications, reconstructive outcomes, and oncologic reporting of propeller flaps in extremity sarcoma reconstruction. A systematic literature search was conducted in PubMed/MEDLINE, Scopus, and the Cochrane Library in accordance with PRISMA 2020. Studies reporting perforator-based propeller flaps after extremity soft tissue sarcoma resection were included. Data were synthesized descriptively because of the heterogeneity of study design, patient populations, and outcome reporting. Nineteen studies were included. Across the published literature, 656 patients were described overall, including 185 propeller flaps used after sarcoma resection. Most reconstructions involved the lower extremity, accounting for more than 95% of reported cases. Flap survival was generally high; among studies providing extractable numerical data, complete flap survival was 92.7% (115/124), total flap loss was 3.8% (2/52), and partial necrosis occurred in 9.6% (5/52) of flaps. Venous congestion was the most frequently reported complication. Oncologic outcomes were inconsistently reported, and comparative recurrence-related data were very limited. Available data suggest that propeller flaps can provide reliable coverage with acceptable complication rates in selected cases. Oncologic outcomes were sparsely and inconsistently reported, and the current literature does not show a clear signal of increased local recurrence; however, the available evidence is insufficient to draw firm conclusions regarding oncologic safety or equivalence compared with other reconstructive strategies. These findings support consideration of propeller flaps as a complementary reconstructive option in carefully selected patients, although higher-quality studies with standardized oncologic outcomes are needed. Full article

Severe nasal vestibular stenosis in brachycephalic cats involves species-specific anatomical structures distinct from those in dogs, often leading to a high recurrence rate even after standard surgical correction. This case report introduces an innovative surgical strategy for a refractory Exotic Shorthair cat presenting with obligate open-mouth breathing and complete nasal obstruction despite three previous surgical interventions. To remove the recurrent scar tissue and maximize the nasal vestibular lumen, a combined surgical approach was performed, incorporating a ventral vertical resection, bilateral wedge resections, and bilateral single pedicle advancement flaps. To maintain the acquired airway and prevent restenosis, a steroid-eluting bioabsorbable implant (PROPEL Contour) was placed within the resected nasal vestibule, marking its first application in veterinary medicine. Postoperatively, open-mouth breathing resolved immediately. At the long-term 20-month follow-up, normal nasal breathing was maintained without restenosis or nasal discharge, with complete resolution of all preoperative clinical signs, and no implant-related adverse effects or infections were observed. The concurrent application of radical structural resection and a PROPEL Contour implant effectively suppresses tissue regrowth and maintains stable nasal patency, offering a highly promising therapeutic protocol for refractory feline nasal vestibular stenosis. Full article

Objective: To investigate the method and clinical outcomes of employing plantar propeller perforator flaps for the repair of defects in the plantar region. Methods: This was a retrospective case series of 40 patients (20 males, 20 females; age range 20–75 years) who underwent plantar defect reconstruction using the horn-shaped perforator flap technique between January 2020 and October 2025. Defect etiologies included malignant melanoma (n = 24), melanocytic nevus (n = 3), and refractory wounds (n = 13). Defect sizes ranged from 2 cm × 1.5 cm to 5 cm × 5 cm. The primary outcome was flap survival; secondary outcomes included functional recovery (American Orthopaedic Foot and Ankle Society AOFAS score), sensory recovery (Semmes–Weinstein monofilaments), and time to full weight-bearing. Results: Complete flap survival was achieved in 38/40 patients (95%). Two patients (5%) experienced minor distal wound dehiscence and necrosis, successfully managed with full-thickness skin grafting and dressing changes without compromising final outcomes. Mean follow-up was 14.2 ± 6.8 months (range 3–24 months). Mean AOFAS score was 91.3 ± 5.6, with 80% achieving excellent functional recovery. Protective sensation was present in 87.1% of the tested patients. Mean time to full weight-bearing was 6.4 ± 1.8 weeks. No local tumor recurrence occurred in melanoma patients during follow-up. Conclusions: The horn-shaped perforator flap provides a reliable source of homologous glabrous skin for reconstructing small-to-medium-sized plantar defects while avoiding skin grafting at the donor site. Its combined rotation–advancement mechanism, flexible triangular leading-edge strategies, and preservation of multiple perforators contribute to favorable functional and aesthetic outcomes. Prospective comparative studies with standardized plantar-specific outcome measures are warranted. Full article

As deep-sea exploration transitions from large-scale search to precision pinpoint operations, the inherent limitations of traditional “rigid-body and propeller” vehicles—specifically in low-speed maneuverability, environmental compliance, and acoustic stealth—are becoming increasingly apparent. Leveraging its unique integrated “gliding-flapping” locomotion and exceptional maneuverability, the manta ray serves as an ideal biological prototype for next-generation deep-sea operational platforms. From a systems engineering perspective, this paper provides a comprehensive review of the current research status and technical evolution of biomimetic manta ray submersibles. First, a technical pedigree centered on “operational depth” is established, illustrating how design paradigms transition from “mechanism replication” in shallow waters to “pressure adaptation” at full-ocean depths. Second, the mechanical challenges in structural design are explored, demonstrating that a “rigid-flexible” gradient distribution strategy is critical to resolving the conflict between pressure resistance and propulsive compliance. Regarding energy and propulsion, the synergistic effects of hybrid gliding-flapping drives and integrated structural batteries in enhancing long-range endurance and energy efficiency are analyzed. Finally, the evolution of motion control architectures—transitioning from spinal-cord-inspired Central Pattern Generator (CPG) rhythmic control to Deep Reinforcement Learning (DRL) featuring embodied intelligence—is outlined. Full article

Background: Perforator flaps improved the reconstruction paradigm in the lower extremity, increasing coverage possibilities. This study aims to quantify how added perforators could enhance standard geometrical patterns (compared to random flaps). Methods: A total of 29 cases of lower limb soft tissue reconstruction (STR)—52% trauma, 21% osteomyelitis with skin fistulas, 21% healing disorders with unstable scarring and 6% cancer-related surgery—were performed in our institution between 2012 to 2023 with geometric random (GR) local flaps (34%), geometric perforator-enhanced (GP) flaps (32%) or pure propeller perforator (PP) flaps (34%), were retrospectively analysed. Patients with proximal thigh defects, a follow up of less than 3 months and those who received an axial, muscle or free flap were excluded. Geometric patterns (as length:width ratio (L:W)) were compared among groups, analysing healing outcomes and complications. Results: Leg defects were categorized into 62% distal, 14% middle, 14% proximal third and 10% distal thigh. No significant difference in defect size was detected among groups. Mean flap size was significantly larger for GP (70.5 cm², (p < 0.05)) and PP (74.4 cm², (p < 0.01)) than GR (53.7 cm²). The L:W ratio was significantly higher in GP (L:W 2.2:1, (p < 0.05)) and PP (L:W 2.8:1, (p < 0.01)) than in GR (1.5:1), but no significant difference was found between GP and PP. A reduced complications rate (partial flap loss, infection, healing, revision surgery, etc.) was observed in the GP group, when compared to GR. Conclusions: Flap geometric design can be significantly improved by the inclusion of perforators, maintaining spatial advantages with larger ductility and improved vascular solidity. Full article

Biomimetic pectoral fin propulsion offers a low-noise, highly maneuverable alternative to conventional propellers for next-generation underwater robotic systems. This study develops a manta ray-inspired dual-servo pectoral fin module with a CPG-based controller and employs it as a single-fin test article in a recirculating water tunnel to quantify its hydrodynamic performance. Controlled experiments demonstrate that the fin generates stable thrust over a range of flapping amplitudes, with mean thrust increasing markedly as the amplitude rises, while also revealing an optimal frequency band in which thrust and thrust work are maximized and beyond which efficiency saturates. To interpret these trends, a quasi-steady CFD analysis using the k–ω SST turbulence model is conducted for a series of static angles of attack representative of the instantaneous effective angles experienced during flapping. The simulations show a transition from attached flow with favorable lift-to-drag ratios at moderate angles of attack to massive separation, deep stall, and high drag at extreme angles, corresponding to high-amplitude fin motion. By linking the experimentally observed thrust saturation to the onset of deep stall in the numerical flow fields, this work establishes a unified experimental–numerical framework that clarifies the hydrodynamic limits of pectoral fin propulsion and provides guidance for the design and operation of low-noise, highly maneuverable biomimetic underwater robots. Full article

The tailless flapping-wing micro aerial vehicle (FW-MAV) exhibits capabilities for hovering and agile six-degree-of-freedom flight, demonstrating potential for missions in complex environments such as forests and indoor spaces. However, limited payload and endurance restrict their practical application. This study presents a novel tailless FW-MAV named X-fly, incorporating a lightweight crank-rocker mechanism with high thrust-to-weight ratio. The optimized flapping-wing mechanism achieves a maximum single-side lift of 28.7 gf, with a lift-to-power ratio of 6.67 gf/W, outperforming conventional direct-drive propellers using the same motor. The X-fly employs servo-controlled stroke planes for tailless attitude stabilization and rapid disturbance recovery. It features a 36 cm wingspan and a net weight of 18.9 g (without battery). Using a commercially available 1100 mAh battery weighing 21.6 g, it demonstrates a peak lift-to-weight ratio of 1.42 at 3.8 V and achieves a maximum flight endurance of 33.2 min. When equipped with a 250 mAh battery weighing 5.5 g, it can carry an additional payload equal to its own net weight. The X-fly attains a maximum speed of 6 m/s and demonstrates high agility during forest flight. Furthermore, it successfully performs a simulated reconnaissance mission with an onboard camera, confirming its potential for practical applications. Full article

Introduction: Bilateral congenital choanal atresia (CCA) is a rare, life-threatening condition in neonates. This is the first reported case of PROPEL steroid-eluting stent use in a seven-day-old bilateral CCA neonate, with a customised technique developed to overcome limitations of the standard applicator. Case Presentation: A full-term male neonate presented with severe respiratory distress and was diagnosed with bilateral CCA. Endoscopic repair with mucoperiosteal flaps and drilling of the atretic plate was performed, followed by placement of a tailored PROPEL stent using a modified insertion with a Nelaton tube system. Outcomes: Recovery was uneventful. At 30 days, the stent remained well-positioned; at two, three, and six months, the neochoana was patent with no restenosis or synechiae. Conclusions: The PROPEL stent, combined with a customised insertion method, may offer a promising alternative for neonatal CCA repair. Further studies are needed to assess long-term outcomes and safety. Full article

Flapping-Wing Aerial Vehicles (FWAVs), which take inspiration from the flight of birds and insects, have gained increasing attention over the past decades due to advantages such as low noise, biomimicry and safety, enabled by the absence of propellers. These features make them particularly suitable for applications in natural environments and operations near humans. However, their complexity introduces significant challenges, including difficulties in take-off and landing as well as limited endurance. Perching represents a promising solution to address these limitations. By equipping these drones with a perching mechanism, they could land on branches to save energy and later exploit the altitude to resume flight without requiring human intervention. Specifically, this review focuses on perching mechanisms based on grasping. It presents designs developed for flapping-wing platforms and complements them with systems originally intended for other types of aerial robots, evaluating their applicability to FWAV applications. The purpose of this work is to provide a structured overview of the existing strategies to support the development of new, effective solutions that could enhance the use of FWAVs in real-world applications. Full article

Introduction: Perforator-based fasciocutaneous flaps are particularly suitable for soft tissue reconstruction of the lower extremities. The most commonly used flap is the microvascular Anterior Lateral Thigh Flap (ALT). Pedicled propeller-type flaps are less frequently utilized due to higher complication rates. The aim of this study was to compare postoperative perfusion patterns of these fundamentally different flaps to increase their basic understanding. Methods: A retrospective data analysis was performed (2017–2022), including patients who underwent flap reconstruction of the lower extremity either with a perforator-based pedicled Propeller flap or free tissue transfer with an ALT flap. Only patients with documented postoperative perfusion monitoring of the flap using the laser Doppler spectrophotometry system (LDSP) were included. Demographic data, comorbidities and perioperative data as well as perfusion profiles given by the LDSP were analyzed. Results: Seven patients who received a propeller flap and 18 who received a free ALT were identified. Defects were most often due to trauma (Propeller flap n = 5; 71.1%; ALT n = 7; 38.9%) and chronic wounds (Propeller flap n = 1; 14.3%; ALT n = 5; 27.8%). The most common complication was prolonged wound healing (Propeller flap n = 3; 42.9%; ALT n = 8; 44.4%). In cases with postoperative surgical complications, a distinctly delayed recovery in perfusion of propeller flaps was seen during the first 72 h after surgery. Conclusions: Propeller and ALT flaps exhibit distinct perfusion patterns, with Propeller flaps showing a congestion-prone profile (elevated rHB, delayed hyperperfusion) and ALT flaps an inflow-dependent, ischemia-driven profile (lower rHB and SO₂). Full article

Background: Propeller perforator flaps (PPFs) have gained increasing popularity in lower limb reconstruction. While their use in elective settings is well described, their role in acute post-traumatic reconstruction remains less defined. Methods: A systematic review was conducted following PRISMA 2020 guidelines. PubMed, Scopus, and Cochrane Library were searched on 2 June 2025, for studies reporting on the use of propeller flaps in lower limb reconstruction after trauma. Only studies rated as “good” quality using the NIH quality assessment tool were included. Data on anatomical location, flap survival, complications, reinterventions, and functional and patient-reported outcomes were extracted and analyzed descriptively. Results: Twenty-eight studies published between 2008 and 2024 were included, accounting for 619 propeller flaps in a population of 838 patients. The majority of flaps were fasciocutaneous, with the posterior tibial artery being the most commonly used source vessel. Among the flaps included, 422 (68.2%) achieved complete survival without necrosis, 84 (13.6%) developed partial necrosis, and 23 (3.7%) failed completely. Considering all flaps that remained viable after any required revisions or conservative management, the overall survival rate was 97%. Venous congestion was the leading cause of flap compromise. The overall complication rate was 21.8%, increasing to 35.1% in acute trauma cases. A statistically significant correlation was found between wide rotation angles (≥150°) and higher complication rates (p = 0.015). The mean follow-up duration was 12.5 months. Functional and aesthetic outcomes were poorly reported, but when available, they were generally favorable. Conclusions: PPFs represent a valuable option for lower limb reconstruction, providing reliable coverage while preserving major vascular axes. Their application in acute trauma settings appears promising, although current evidence is limited by small verified cohorts and predominantly retrospective study designs. Despite higher complication rates in acute cases, flap survival remains consistently high, supporting their use in carefully selected patients. Further prospective studies with standardized outcome reporting are needed to clarify long-term functional results and refine selection strategies. Full article

Background and Objectives: Lower limb defects often present significant reconstructive challenges due to limited soft tissue availability and exposure of critical structures. Perforator-based flaps offer reliable solutions, with minimal donor site morbidity. This study aimed to evaluate the efficacy of infrared thermography (IRT) in preoperative planning and postoperative monitoring of perforator-based flaps, assessing its accuracy in identifying perforators, predicting complications, and optimizing outcomes. Materials and Methods: A prospective observational study was conducted on 76 patients undergoing lower limb reconstruction with fascio-cutaneous perforator flaps between 2022 and 2024. Perforator mapping was performed concurrently with IRT and Doppler ultrasonography (D-US), with intraoperative confirmation. Flap design variables and systemic parameters were recorded. Postoperative monitoring employed thermal imaging on days 1 and 7. Outcomes were correlated with thermal, anatomical, and systemic factors using statistical analyses, including t-tests and Pearson correlation. Results: IRT showed high sensitivity (97.4%) and positive predictive value (96.8%) for perforator detection. A total of nine minor complications occurred, predominantly in patients with diabetes mellitus and/or elevated glycemia (p = 0.05). Larger flap-to-defect ratios (A/C and B/C) correlated with increased complications in propeller flaps, while smaller ratios posed risks for V-Y and Keystone flaps. Thermal analysis indicated significantly lower flap temperatures and greater temperature gradients in flaps with complications by postoperative day 7 (p < 0.05). CRP levels correlated with glycemia and white blood cell counts, highlighting systemic inflammation’s impact on outcomes. Conclusions: IRT proves to be a reliable, non-invasive method for perforator localization and flap monitoring, enhancing surgical planning and early complication detection. Combined with D-US, it improves perforator selection and perfusion assessment. Thermographic parameters, systemic factors, and flap design metrics collectively predict flap viability. Integration of IRT into surgical workflows offers a cost-effective tool for optimizing reconstructive outcomes in lower limb surgery. Full article

This paper establishes an analytical model for component mass, takeoff weight, and performance constraints of distributed electric propulsion (DEP) propeller-driven short takeoff and landing (STOL) unmanned aerial vehicles (UAV), and develops a conceptual design method considering propulsive/aerodynamic coupling effects. The proposed approach was applied to design a 350 kilogram-class DEP UAV with STOL capability, verifying the feasibility and effectiveness of the design method. To investigate the layout design and propulsive/aerodynamic coupling characteristics of DEP UAV, three UAV configurations with different DEP arrangements are formulated and studied, and the results indicate that the flap deflection significantly increases the lift coefficient of the UAV during takeoff, and under the same total thrust and power conditions, the lift-enhancement using DEP arrangement is more significant. In addition, it is necessary to fully consider the propulsive/aerodynamic coupling effects in the conceptual design process, and this is of great significance for the future development of DEP STOL UAV. Full article