Estudo de retalhos venosos arterializados no modelo experimental de rato wistar e no cadáver humano

RESUMO:Introdução: Os retalhos de perfusão não convencionais (UPFs) são opções reconstrutivas caracterizadas por serem perfundidas exclusivamente por veias. Nos UPFs, pelo menos uma das veias aferentes do retalho é anastomosada a um vaso de alimentação. Normalmente, este vaso de alimentação é uma artéria, e o UPF é chamado de retalho venoso arterializado (AVF). Se o vaso de alimentação for uma veia, o UPF é chamado de retalho venoso (VF). O fluxo de sangue é assegurado na maioria dos casos pela continuidade de uma ou mais veias do UPF com veias vizinhas. Embora os UPFs apresentem várias vantagens potenciais em relação aos retalhos de perfusão convencionais (CFs), raramente são mencionados na literatura, devido às altas taxas de necrose relatadas, particularmente na presença de infeção, e devido a uma má compreensão de seus mecanismos fisiológicos subjacentes. Métodos: Realizámos revisões sistemáticas e metanálises sobre o uso clínico e experimental dos UPFs. Seguidamente, estudamos detalhadamente a anatomia vascular do aspecto ventrolateral do abdômen do rato. Com esse conhecimento, melhoramos o modelo de um retalho convencional colhido na região epigástrica. Posteriormente, desenvolvemos um modelo otimizado de AVF no abdómen do rato. Avaliamos o efeito de transfectar este modelo otimizado com genes de beta defensina humana (BD-2 e BD-3) para aumentar a sobrevivência do retalho na presença de infecção por Pseudomonas aeruginosa e de um corpo estranho. Além disso, comparamos a eficácia dos retalhos neurovenosos arterializados (ANVFs) com outros condutos nervosos com o intuito de reconstruir um hiato de 10 mm no nervo mediano do rato num ambiente de isquémia local. Seguidamente, realizamos estudos cadavéricos para avaliar os aspetos pertinentes da anatomia e histologia das regiões anatômicas comumente usadas para colher UPFs. Finalmente, usamos algumas das informações coletadas para tratar um adolescente com um defeito do pedículo vásculo-nervoso ulnar ao nível do antebraço. Resultados: Estimámos uma taxa de sobrevivência global de UPFs de 89,5% no contexto clínico e de 90,8% em condições experimentais. Clinicamente, houve uma correlação positiva entre a taxa de infeção pós-operatória e a necessidade de um novo retalho (coeficiente de Pearson 0,405; p = 0,001). O fornecimento de sangue ao tegumento abdominal do rato era sobretudo dependente dos vasos axiais, contrastando com o que acontece no Homem. Válvulas venosas foram claramente observadas nesta região. O retalho convencional epigástrico livre e o AVF otimizada homólogo apresentaram taxas de sobrevivência de quase 100% e 76,86 ± 13,67%, respectivamente. Transfectando-se o modelo de AVF com BD-2 e BD-3, observou-se aumento da sobrevivência do retalho e diminuição da formação de biofilmes. Os ANVFs produziram uma recuperação mais completa e mais rápida do que os enxertos nervosos, para a maioria dos parâmetros utilizados para avaliar a regeneração nervosa. Estudos anatómicos e histológicos revelaram que as veias subcutâneas de maiores dimensões encontravam-se envolvidas por desdobramentos da fáscia superficial. Além disso, as veias encontravam-se em profundidades diferentes, estando as maiores colocadas profundamente e as mais pequenas localizadas mais superficialmente. Finalmente, observou-se que os nervos cutâneos superficiais, rotineiramente utilizados como enxertos de nervos autólogos, estavam mais próximos das veias superficiais do que das artérias e respetivas veias comitantes com calibre significativo. Os UPFs podem ser adaptados a defeitos específicos, incluindo pele, tecido celular subcutâneo, tendões, nervos, fáscia muscular e / ou osso em combinações variáveis. O uso de um ANVF no referido adolescente permitiu a reconstrução dos defeitos arterial e nervoso com sucesso. Conclusão: Apesar de muitas questões continuarem por responder em relação à fisiologia, otimização e indicações dos UPFs, parece haver evidência suficiente para apoiar seu uso no âmbito da reconstrução tegumentar e nervosa.ABSTRACT: Introduction: Unconventional perfusion flaps (UPFs) are reconstructive options characterized by being perfused exclusively by veins. In UPFs at least one of the afferent veins of the flap is anastomosed to a feeding vessel. Usually, this feeding vessel is an artery, and the UPF is called an arterialized venous flap (AVF). If the feeding vessel is a vein, the UPF is called a venous flap (VF). The efflux of blood is ensured in most cases by the continuity of one or more of the UPF’s veins with neighboring veins. Although UPFs present several potential advantages relatively to conventional perfusion flaps, they have rarely been mentioned in the clinical literature, due to reported high necrosis rates, particularly in the presence of infection, and due to a poor understanding of their underlying physiologic mechanisms. Methods: We performed systematic reviews and meta-analyses on the clinical and experimental used of UPFs. Followingly, we studied in detail the vascular anatomy of the ventrolateral aspect of the rat’s abdomen. Using this knowledge, we improved a model of a conventional flap (CF) harvested from the epigastric region of the fat. Subsequently, we developed an optimized a model of AVF in the abdomen of the rat. We, then, evaluated the effect of transfecting the optimized model with human beta defensin genes (BD-2 and BD-3) to increase flap survival in the presence of Pseudomonas aeruginosa infection and of a foreign body. Moreover, we compared the efficacy of arterialized neurovenous flaps (ANVFs) with other nerve conduits to reconstruct a 10-mm-long median nerve gap in an ischemic environment in a rat model. Followingly, we performed cadaveric studies to assess pertinent aspects of the anatomy and histology of anatomical regions commonly used to harvest UPFs. Finally, we used some of the information gathered to treat a teenager with an ulnar artery and nerve composite defect at the forearm level. Results: We estimated an overall survival rate of UPFs of 89.5% in the clinical context and of 90.8% in the experimetal setting. Clinically, there was a positive correlation between the rate of postoperative infection and the need of a new flap (Pearson coefficient 0.405; p=0.001). Blood supply to the abdominal integument of the rat was more dependent on axial vessels, comparatively to humans. Venous valves were clearly observed in this region. The free epigastric CF and the homologous optimized AVF presented survival rates of nearly 100%, and 76.86 ± 13.67%, respectively. Transfecting the AVF model with BD-2 and BD-3 increased flap survival, and decreased biofilm formation. ANVFs produced more complete and faster recovery than nerve grafts, for most of the parameters used to assess nerve regeneration. Anatomical and histological studies revealed that large subcutaneous veins were surrounded by doublings of the superficial fascia. Moreover, veins were placed at different depths, with the largest ones being deeply placed and the smallest more superficially placed. Finally, it was noted that superficial cutaneous nerves, routinely used as autologous nerve grafts, were closer to sizeable superficial veins than to arteries and respective comitante veins of significant caliber. UPFs could be tailored to specific defects by including either skin, subcutaneous tissue, tendons, nerves, muscle fascia and/or bone in variable combinations. The used of an ANVF in a teenager allowed the successful reconstruction of both the arterial and nerve defects. Conclusion: Although many question remain to be answered relatively to UPFs physiology, optimization, and indications, there seems to be enough evidence to support their use in the realm of integumentary and nerve reconstruction.RÉSUMÉ: Introduction: Les lambeaux de perfusion non conventionnels (UPF) sont des options de reconstructives caractérisées par une perfusion exclusive pour le veines. Dans les UPF, il ya au moins une des veines afférentes du Lambeau qui est anastomosée à un vase d'alimentation. Habituellement, ce vaisseau d'alimentation est une artère, et l'UPF s'appelle un lambeau veineux arterialisé (AVF). Si le vaisseau est une veine, l'UPF s'appelle un lambeau veineux (VF). L'effusion de sang est assurée dans la plupart des cas par la continuité d'une ou plusieurs veines de l'UPF avec des veines voisines. Bien que les UPF présentent plusieurs avantages potentiels par rapport aux lambeaux de perfusion conventionnels, ils ont rarement été mentionnés dans la littérature clinique, en raison des taux élevés de nécrose reportés, en particulier en présence d'une infection, et en raison d'une mauvaise compréhension de leurs mécanismes physiologiques. Méthodes: Nous avons procédé à deux analyses systématiques et méta-analyses sur l'utilisation clinique et expérimentale des UPFs. Nous avons étudié en détail l'anatomie vasculaire de l'aspect ventral de l'abdomen du rat. À l'aide de cette connaissance, nous avons amélioré un modèle de lambeau conventionnel (CF) récolté dans la région épigastrique de l’abdomen. Par la suite, nous avons développé un modèle optimisé d'AVF dans l'abdomen du rat. Nous avons ensuite évalué l'effet de la transfection du modèle optimisé avec les gènes de la beta-defensine humaine (BD-2 et BD-3) pour augmenter la survie des lambeaux en présence d'une infection pour Pseudomonas aeruginosa et d'un corps étranger. Nous avons aussi comparé l'efficacité des lambeaux neurovenous arterialisés (ANVF) avec d'autres conduits nerveux pour reconstruire un hiatus nerveux de le nerf médian de 10 mm de longueur dans un environnement ischémique dans le modèle de le rat Wistar. Par la suite, nous avons effectué des études cadavériques pour évaluer les aspects pertinents de l'anatomie et de l'histologie des régions anatomiques couramment utilisées pour récolter des UPFs. Enfin, nous avons utilisé une partie des informations recueillies pour traiter un adolescent souffrant d'un défaut composite de l’artère ulnaire e de le nerf ulnaire au niveau de l'avant-bras. Résultats: Nous avons estimé un taux global de survie des UPF de 89,5% dans le contexte clinique et de 90,8% dans le contexte expérimental. Cliniquement, il y avait une corrélation positive entre le taux d'infection postopératoire et la besoin d'un nouveau lambeau (coefficient de Pearson 0,405; p = 0,001). L'approvisionnement en sang du tégument abdominal du rat dépendait davantage des vaisseaux axiaux, comparativement aux humains. Les valves veineuses ont été clairement observées dans cette région. Le lambeau épigastrique conventionnel livre et l'AVF homologue optimisée ont présenté des taux de survie de près de 100% et 76,86 ± 13,67%, respectivement. Transféction de le modèle AVF optimisée avec BD-2 et BD-3 augmenté la survie du lambeau et la formation de biofilm a été diminuée. Les ANVF ont produit une récupération plus complète et plus rapide que les greffes nerveuses, pour la plupart des paramètres utilisés pour évaluer la régénération nerveuse. Des études anatomiques et histologiques ont révélé que les grandes veines sous-cutanées étaient entourées de doublures du fascia superficiel. De plus, les veines ont été placées à différentes profondeurs, les plus grandes étant profondément placées et les plus petites placées plus superficiellement. Enfin, il a été noté que les nerfs cutanés superficiels, habituellement utilisés comme greffes autologues, étaient plus proches des veines superficielles importantes que des artères et des veines comitantes respectives de calibre significatif. Les UPF pourraient être adaptés à des défauts spécifiques en incluant la peau, le tissu sous-cutané, les tendons, les nerfs, le fascia musculaire et / ou l'os dans des combinaisons variables. L'utilisation d'un ANVF chez un adolescent a permis la reconstruction réussie des défauts artériels et nerveux. Conclusion: Bien que beaucoup de questions restent à répondre par rapport à la physiologie, à l'optimisation et aux indications de l'UPF, il semble y avoir suffisamment des preuves scientifiques pour favoriser leur utilisation dans le domaine de la reconstruction de l’integument et des les nerfs

Images in rheumatology. A variant of the distal ulna in a patient with ulnar impaction syndrome

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Sciatic Nerve High Division: Two Different Anatomical Variants

Introduction: Sciatic nerve variations are relatively common. These variations are often very significant in several fields of Medicine. The purpose of this paper is to present two such variants and discuss their clinical implications. Material and Methods: Three Caucasian cadavers with no prior history of lower limb trauma or surgery were dissected and found to present anatomical variants of the sciatic nerve. Results: In all cases the sciatic nerve divided above the popliteal fossa. In two cases (cadavers 1 and 2) it divided on both sides in the inferior portion of the gluteal region in its two terminal branches: the common fibular and the tibial nerves. In another case (cadaver 3) the sciatic nerve was found to divide inside the pelvis just before coursing the greater sciatic notch. The common fibular nerve exited the pelvis above the pyriformis muscle and then passed along its posterior aspect, while the tibial nerve coursed deep to the pyriformis muscle. Discussion: According to the literature, the anatomical variant described in cadaver 3 is considered relatively rare. This variant can predispose to nerve entrapment and thus to the pyriformis syndrome, sciatica and coccygodynia. The high division of the sciatic nerve, as presented in cadavers 1 and 2, can make popliteal nerve blocks partially ineffective. Conclusion: The anatomical variants associated with a high division of the sciatic nerve, must always be born in mind, as they are relatively prevalent, and have important clinical implications, namely in Anesthesiology, Neurology, Sports Medicine and Surgery.publishersversionpublishe

P6 CFD Modelling of Arterialized Venous Flap

The knowledge about the required quantity of blood to irrigate an angiosome is important on ischemia (disruption on blood perfusion) prediction, diagnosis and treatment. An angiosome (or flap) is an anatomic unity (or flap) of tissue, it is constituted by skin, subcutaneous tissue and muscle, it is irrigated by an artery and drain by specific veins [1]. Since 70’s, flaps have been used on clinical practice for reconstruction of complex anatomical structures. Different model configurations have been created, to find a flap’s model that allows a better flap perfusion. In previous work [2] the four models with an average flap survival area of 76.86% ± 13.67% were tested in 53 male rats: I - conventional model of flap’s blood supply formed by femoral and epigastric arteries; II – Arterialized Venous Flap (AVF) produced by femoral side-to-side anastomosis; III - AVF produced by femoral side-to-side anastomosis and proximal ligation of the femoral vein; IV - AVF produced by terminal lateral anastomosis of the epigastric vein to the femoral artery). The experimental results have shown that the AVFs in group IV represent an optimized model of unconventional perfusion flap. In the present work the Computational Fluid Dynamics (CFD) methods, an ANSYS®-Fluent code, were used for simulating a blood flow and flap perfusion in AVFs of group IV in order to find an optimum geometry for lateral anastomosis of the epigastric vein to the femoral artery with an angle variation from 90,0º to 45,0º. We find that the optimum angle is 86,5º. Three other models, conventional and unconventional, was also tested by CFD, finding that unconventional AVF of group III provides a greater blood flow through the epigastric vein, allowing a better perfusion of the flap.publishersversionpublishe

A case report

INTRODUCTION: Calcaneal osteomyelitis poses a tough challenge for any reconstructive surgeon. The eradication of the infection and the reconstruction of the defect are the main goals of treatment. PRESENTATION OF CASE: We present the case of a 53-year-old male with chronic calcaneal osteomyelitis. The patient was submitted to several bone and soft tissue debridements and twice the application of gentamicin/sulfate implants at the wound bed with no success. He was then submitted to a partial calcanectomy followed by obliteration of the bone defect (4.5 × 2 × 1.5 cm) with a free vascularized fibula-flexor hallucis longus osteomuscular flap (bone dimension:4.5 × 1.5 × 1.2 cm; muscle size: 4 × 1.5 × 0.5 cm). The flap remained viable, and the post-operative period was uneventful. Bone incorporation was evident nine months after the surgery with no signs of recurrent infection or avascular necrosis. Final follow up, at one year, showed an excellent functional result. The patient was able to ambulate without assistance and referred occasional minimal foot pain. Donor site morbidity was minimal. CONCLUSION: The authors believe that this osteomuscular flap may be a valuable option to reconstruct calcaneal defects after chronic osteomyelitis.publishersversionpublishe

Evaluation of different analytical approaches using total reflection X-ray fluorescence systems for multielemental analysis of human tissues with different adipose content

Publisher Copyright: © 2022 The AuthorsElemental content plays an important role in biological processes, and so, the multielemental analysis of human tissue samples is required in biomedical research. Still, the small amount of available biological samples and the adipose content of the samples can be major setbacks for the accurate determination of elemental content. In this study, we explored the potential of several analytical approaches combined with total reflection X-ray fluorescence spectrometry (TXRF) for multielemental analysis of human tissues with different adipose content (colon, heart, liver, lung, muscle, intestine, skin, stomach, uterus, bladder and aorta). The capabilities and limitations of different sample treatment procedures (suspension and acidic digestion) and two TXRF systems with different anode configurations (Mo and W X-ray tubes) have been evaluated for such purpose. Results showed that for tissues with a higher fat content (e.g., skin, and intestine) the best strategy was the acidic digestion of the sample before TXRF analysis. However, for other tissues, acceptable results were obtained by suspending 20 mg of powdered material in 1 mL of 2 M nitric acid. A further enhancement of the limits of detection and accuracy of the results was achieved if using Mo-TXRF systems, especially for the determination of low Z elements (e.g., K, and Ca) and of elements present at low concentrations (e.g., Cu) in the human tissues. Finally, results by TXRF analysis were compared with those obtained with μ-EDXRF and ICP-OES, and a good agreement was obtained.publishersversionpublishe