Diagnostical accuracy of hyperspectral imaging after free flap surgery.

Microsurgical free-tissue transfer has been a safe option for tissue reconstruction. This study aimed to analyze the diagnostic accuracy of hyperspectral imaging (HSI) after free-tissue transfer surgery. From January 2017 to October 2019, 42 consecutive free-flap surgeries were performed, and their outcomes were analyzed via HSI. Clinical examination of free-flap perfusion was initially performed. Clinical examination findings were subsequently compared with those of HSI. Potential venous congestion with subsequent necrosis was defined as a tissue hemoglobin index of ≥53%. Student's t-test was used to compare the results of the analysis. The evaluation of sensitivity and specificity for flap failure detection was time dependent using the Fisher's exact test. A p-value of ≤0.05 was considered statistically significant. Microsurgical tissue transfer success rate was 84%. Seven patients presented with venous congestion that caused total flap necrosis. Overall, 124 assessments were made. HSI accurately identified 12 out of 19 pathological images: four as false positive and seven as false negative. The sensitivity and specificity of HSI were 57 and 94%, respectively, compared to those of clinical examination that were 28 and 100%, respectively, within 24 h following tissue transfer. The sensitivity and specificity of HSI were 63 and 96%, respectively, compared to those of clinical examination that were 63 and 100%, respectively, within the first 72 h. A tissue hemoglobin index of ≥53% could predict venous congestion after free-flap surgery. HSI demonstrated higher sensitivity than clinical examination within the first 24 h; however, it was not superior compared to clinical findings within 72 h.

Tolerable degree of muscle sacrifice when harvesting a vastus lateralis or myocutaneous anterolateral thigh flap.

The myocutaneous anterolateral thigh (ALT) and vastus lateralis (VL) flaps include a large muscle mass and a sufficient vascular pedicle, and they have been used for decades to reconstruct traumatic and acquired defects of the head and neck and extremities. In spite of these benefits, musculoskeletal dysfunction was reported in nearly 1 out of 20 patients at follow-up. It is unclear whether the recently proposed muscle-sparing flap-raising approach could preserve VL muscle function and whether patients at increased risk could benefit from such an approach. Therefore, we performed a predictive dynamic gait simulation based on a biological motion model with gradual weakening of the VL during a self-selected and fast walking speed to determine the compensable degree of VL muscle reduction. Muscle force, joint angle, and joint moment were measured. Our study showed that VL muscle reduction could be compensated up to a certain degree, which could explain the observed incidence of musculoskeletal dysfunction. In elderly or fragile patients, the VL muscle should not be reduced by 50% or more, which could be achieved by muscle-sparing flap-raising of the superficial partition only. In young or athletic patients, a VL muscle reduction of 10%, which corresponds to a muscle cuff, has no relevant effect. Yet, a reduction of more than 30% leads to relevant weakening of the quadriceps. Therefore, in this patient population with the need for a large portion of muscle, alternative flaps should be considered. This study can serve as the first basis for further investigations of human locomotion after flap-raising.

Smoking and microvascular free flap perfusion in head and neck reconstruction: radial free forearm flaps and anterolateral thigh flaps.

Head and neck reconstruction with microvascular free flaps is frequently performed in smokers. Smoking causes various alterations in the cardiovascular system. The aim of this study was to investigate the effects of smoking on flap perfusion as a critical factor for flap survival. A total of 370 patients reconstructed with a radial free forearm flap (RFFF) or anterolateral thigh flap (ALTF) in the head and neck region between 2011 and 2020 were retrospectively analyzed. Flap perfusion measurements with the O2C tissue oxygen analysis system were compared between nonsmokers, light smokers (< 20 pack-years), and heavy smokers (≥ 20 pack-years). The blood flow was intraoperatively equal in RFFFs (84.5 AU vs. 84.5 AU; p = 0.900) and increased in ALTFs (80.5 AU vs. 56.5 AU; p = 0.001) and postoperatively increased in RFFFs (114.0 AU vs. 86.0 AU; p = 0.035) and similar in ALTFs (70.5 AU vs. 71.0 AU; p = 0.856) in heavy smokers compared to nonsmokers. The flap survival rate was similar in nonsmokers, light smokers, and heavy smokers (97.3%, 98.4%, and 100.0%). Smoking partially increases rather than decreases microvascular free flap perfusion, which may contribute to similar flap survival rates in smokers and nonsmokers.

Infections in Burn Patients: A Retrospective View over Seven Years.

Backgroundand objectives: Burn patients represent a challenging cohort because the injuries entail a vulnerability to colonisation by microorganisms. The ensuing infections can lead to serious complications and, in many cases, to the death of the burn patient. Surgical intervention and wound dressings, as well as antibiotic treatment, are crucial for optimising the treatment of the patient. Materialand Methods: In this retrospective analysis, we analysed the treatment course, antibiotic therapy, and general complications of 252 burn patients with second- or third-degree burns over a time span of 7 years. Results: Patients who developed infections tended to have, on average, a higher total body surface area (TBSA), higher abbreviated burn severity index (ABSI) scores, and longer hospital stays. Patients who were admitted to the burn unit after 2006 had significantly shorter stays in the burn unit. TBSA and ABSI scores were lower in the patient cohort admitted after 2006. Patients exhibiting a TBSA greater than 30% had significantly longer hospital stays and antibiotic treatment periods. TBSA and ABSI scores were significantly higher in patients who died. The results of binary logistic regression indicate that a higher ABSI score increases the odds ratio of developing an infection. Bacteria number had no significant effect on the odds of patient death but positively influenced the odds ratio of developing an infection. TBSA was negatively associated with the risk of developing an infection and was an insignificant predictor of mortality. Conclusions: To gauge the optimal treatment for a burn patient, it is crucial for practitioners to correctly select, dose, and time antibiotics for the patient. Monitoring bacterial colonisation is vital to nip rising infection in the bud and ensure the correct antibiotic selection. This will help prevent the development of multi-resistant bacteria.

Automated PD-L1 Scoring Using Artificial Intelligence in Head and Neck Squamous Cell Carcinoma.

Immune checkpoint inhibitors (ICI) represent a new therapeutic approach in recurrent and metastatic head and neck squamous cell carcinoma (HNSCC). The patient selection for the PD-1/PD-L1 inhibitor therapy is based on the degree of PD-L1 expression in immunohistochemistry reflected by manually determined PD-L1 scores. However, manual scoring shows variability between different investigators and is influenced by cognitive and visual traps and could therefore negatively influence treatment decisions. Automated PD-L1 scoring could facilitate reliable and reproducible results. Our novel approach uses three neural networks sequentially applied for fully automated PD-L1 scoring of all three established PD-L1 scores: tumor proportion score (TPS), combined positive score (CPS) and tumor-infiltrating immune cell score (ICS). Our approach was validated using WSIs of HNSCC cases and compared with manual PD-L1 scoring by human investigators. The inter-rater correlation (ICC) between human and machine was very similar to the human-human correlation. The ICC was slightly higher between human-machine compared to human-human for the CPS and ICS, but a slightly lower for the TPS. Our study provides deeper insights into automated PD-L1 scoring by neural networks and its limitations. This may serve as a basis to improve ICI patient selection in the future.

Ultrasound Analysis of Lateral Ankle Ligaments in Functional Ankle Instability.

The anterior talofibular ligament and the calcaneofibular ligament were sonographically investigated in 16 patients with functional ankle instability (FAI) and 16 controls under neutral and standardized stress conditions of 15 kp with a TELOS device. Clinical investigation revealed a significantly higher rate of a positive anterior drawer and talar tilt (p <0.001, respectively), significantly increased supination (p = 0.047) of the right ankle joint and increased plantarflexion (p = 0.009) of the left ankle joint in the FAI group compared with controls. Significantly higher rates of inhomogeneity and hypo-echogenicity were sonographically observed in both ligaments in the FAI group (p < 0.05, respectively). The anterior talofibular ligament was significantly longer under stress conditions, and the calcaneofibular ligament was significantly longer under both neutral and stress conditions in the FAI group (p < 0.05, respectively). Peritendinous edema of the peroneal tendons was found in 22% of the FAI group and 6% of controls.

[Hyperspectral imaging for postoperative flap monitoring of pedicled flaps]. / Hyperspektralimaging zum postoperativen Lappenmonitoring von lokoregionären Lappenplastiken.

BACKGROUND: Since pedicle flaps were first described by the Indian physician Sushruta Samhita in the 6th century B. C., they have become an integral part of reconstructive surgery. As more and more research has been conducted into the underlying physical principles, flap monitoring has developed steadily in the last few decades. Hyperspectral Imaging (HSI) is a new quantitative measuring method for assessing the perfusion of the underlying tissue. OBJECTIVE: This study aims to evaluate HSI as a monitoring method for pedicle flaps. PATIENTS AND METHODS: In 16 patients who had undergone reconstructive surgery, oxygen saturation, haemoglobin and water concentration of the locoregional flap, necrotic flap areas as well as intact skin were measured on postoperative days 1 to 7. Subsequently, the data were statistically described and graphically illustrated. RESULTS: HSI revealed increased haemoglobin concentration and decreased oxygen and water concentration in necrotic flap areas compared with the monitor island and healthy skin. The distribution of the values collected from the vital skin areas and the monitor island was almost identical. CONCLUSION: HSI allows for safe, immediate, non-contact measurement of tissue perfusion of transferred tissue areas in patients after pedicle flap surgery. The use of HSI may improve postoperative flap monitoring.

Registration of digital dental models and cone-beam computed tomography images using 3-dimensional planning software: Comparison of the accuracy according to scanning methods and software.

INTRODUCTION: The registration of cone-beam computed tomography (CBCT) images and digital dental models is required for the design and manufacturing of dental devices such as implant guides and surgical wafers. This study aims to register intraoral scan (IS) models and cast scan (CS) models onto CBCT images using 3-dimensional (3D) planning software and evaluate the registration accuracy according to scanning methods and 3D planning software. METHODS: The CBCT image of an artificial skull model with reference markers was taken. The CS model and the IS model were obtained from the same skull model, registered onto the CBCT image using 3D planning software packages providing manual registration (MR) function and point-based registration (PR) functions, and set as the experimental groups. After registration, shell to shell deviations and positional differences between the reference model and the experimental models were evaluated. RESULTS: The shell to shell deviations ranged from 0.03 to 0.18 mm. Deviations in both the maxilla and mandible were significantly different according to scanning methods and software packages. In the anteroposterior direction, the IS-MR and CS-MR groups showed significantly different positions. In the superoinferior direction, the MR and PR groups showed significantly different positions. CONCLUSIONS: The registration using the PR function of the 3D planning software packages was significantly more accurate than the registration using the MR function. There was no significant difference between the registrations using the IS model and the CS model when using the PR functions.

Structural topography of the interosseous membrane of the human forearm.

The aim of this study was to evaluate the morphology of the six different parts of the interosseous membrane (IOM) in 11 human cadaver forearms, including the distal oblique bundle (DOB), the distal accessory band (DAB), the central band (CB), the proximal accessory band (PAB), the dorsal oblique accessory cord (DOAC), and the proximal oblique cord (POC). Hematoxylin-eosin and Elastica van Gieson stained slices were used to investigate the tissue morphology. The DOB and DOAC were absent in one IOM and the POB in two IOMs, respectively. The CB and DAB were longer than all other structures except for each other. The DOAC was longer than the DOB. The DAB, CB, and PAB, were broader than the DOB, DOAC, and POC. No significant differences were observed regarding structure thickness. All structures were found to consist of densely packed parallel collagen fiber arrangement. The DOB and POC had a higher amount of elastic fibers in the fascicular collagen tissue than the other structures. Elastic fibers were more often equally distributed throughout the structures than condensed epifascicular or at the insertion into bone. The tight parallel collagen composition within the different structures reflects the central stabilizing role of the IOM in the forearm. The higher amount of elastic fibers within the DOB and POC can be attributed to their location close to the distal and proximal radioulnar joints, respectively. Here elastic fibers allow adaption to forearm rotation, whereas the structures of the central part of IOM have less elasticity reflecting the predominant stabilizing function.

Molecular Mechanisms of Hair Growth and Regeneration: Current Understanding and Novel Paradigms.

Hair is a defining feature of mammals and has critical functions, including protection, production of sebum, apocrine sweat and pheromones, social and sexual interactions, thermoregulation, and provision of stem cells for skin homeostasis, regeneration, and repair. The hair follicle (HF) is considered a "mini-organ," consisting of intricate and well-organized structures which originate from HF stem and progenitor cells. Dermal papilla cells are the main components of the mesenchymal compartments in the hair bulb and are instrumental in generating signals to regulate the behavior of neighboring epithelial cells during the hair cycle. Mesenchymal-epithelial interactions within the dermal papilla niche drive HF embryonic development as well as the postnatal hair growth and regeneration cycle. This review summarizes the current understanding of HF development, repair, and regeneration, with special focus on cell signaling pathways governing these processes. In particular, we discuss emerging paradigms of molecular signaling governing the dermal papilla-epithelial cellular interactions during hair growth and maintenance and the recent progress made towards tissue engineering of human hair follicles.

[Elevation of Myostatin as a Potential Marker for Compartment Syndrome in Electrical Injuries]. / Myostatin als potenzieller Marker für das Kompartmentsyndrom bei elektrischen Verletzungen.

INTRODUCTION: Electrical accidents and particularly subsequent compartment syndromes are challenging injuries for clinical treatment. Creatinine kinase (CK) and myoglobin are known lab parameters to detect a compartment syndrome. METHODS: We followed up patients with electrical injuries between the years 2006 and 2016 at our burn unit. We aimed to analyse the role of myostatin as marker for compartment syndrome through serum measurements within 48 hours after injury. RESULTS: We collected data from 24 patients hospitalised with high-voltage electrical injury. All patients were male. We measured myostatin in 14 of these patients. While CK-MB (creatinine kinase muscle-brain type [MB]) showed no significant correlation to compartment syndrome, CK and myostatin gave highly significant increases. Interestingly, myostatin was significantly increased in electrical injuries but not burn injuries, while CK did not show a significant difference. CONCLUSION: Thus, besides CK, myostatin can serve as reliable early marker for compartment syndrome in electrical injuries.

[Microsurgical soft tissue reconstruction in lower extremity osteitis]. / Mikrochirurgische Weichteilrekonstruktion bei Osteitis der unteren Extremität.

BACKGROUND: The aim of this study was to analyse retrospectively the pre- and intraoperative factors influencing flap loss after free flap coverage of septic skin defects caused by osteitis of the lower extremity with an anterolateral thigh flap (ALT) or latissimus dorsi (LD) flap. MATERIAL AND METHODS: Twenty-seven patients were surgically treated with LD flap coverage and 45 patients with ALT flap coverage between 2004 and 2013. Their anthropometric, pre- and intraoperative parameters were investigated retrospectively. RESULTS: Flap survival was 81.5 % for LD flaps and 82.2 % for ALT flaps. Major complications led to a significantly higher flap loss both in LD (p = 0.01) and ALT flaps (p < 0.0001). Furthermore, there was a significant increase in flap loss with pre-existing diabetes mellitus in the LD group (p = 0.001) and with acute osteomyelitis being the underlying cause of the soft tissue defect in the ALT group (p = 0.034). Regardless of the flap's postoperative success, LD flaps were used for significantly larger soft tissue defects to be reconstructed (p = 0.001), with the duration of surgery (p < 0.0001) and cold ischaemia time (p = 0.001) being significantly longer compared with ALT flaps. CONCLUSIONS: The success of microsurgical flap reconstruction in lower extremities after osteitis was influenced by a low number of cases with preexisting diabetes mellitus, causative acute osteomyelitis, and major complications. Therefore, optimal management of both parameters and precise microsurgical anastomosis are prerequisites for successful plastic reconstruction of soft tissue defects.

Five Years Experience With Meek Grafting in the Management of Extensive Burns in an Adult Burn Center.

BACKGROUND: In extensive burn injuries with lack of donor sites for skin grafting, the Meek technique of skin expansion can be an efficient and effective method in covering extensive wounds. The aim of this retrospective study was to present our experience with the Meek technique of grafting. METHODS: We performed a retrospective analysis of patients from our burn center who underwent Meek grafting between 2012 and 2016. Demographics, burn details, clinical course, operative management, and outcomes were collected and analyzed from patient records and operative notes. Outcome measures, including graft take rate, complications and need for further surgery, were recorded. RESULTS: Twelve patients had Meek grafting. The average age was 38 years (range: 15-66). The average percent total body surface area burned was 54.3% (range: 31%-77%). Eighty-three percent of grafted areas healed well, and no regrafting was necessary. In the remaining 17%, infection and hematoma were the leading cause of graft failure. CONCLUSIONS: Meek grafting constitutes a rapid and efficient surgical approach for the skin coverage of extensive full-thickness burn injuries with limited autograft donor sites.

HISTORIQUE: En cas de brûlures étendues et en l'absence de siège de donneur pour procéder aux greffes cutanées, la technique Meek d'expansion cutanée peut être une méthode efficace et efficiente pour recouvrir des plaies étendues. Cette étude rétrospective vise à présenter l'expérience des auteurs relativement à la technique de greffe Meek. MÉTHODOLOGIE: Les auteurs ont procédé à l'analyse rétrospective de patients du centre pour grands brûlés qui ont subi la technique de greffe Meek entre 2012 et 2016. Ils ont recueilli les données démographiques, les détails des brûlures, l'évolution clinique, la prise en charge opératoire et les résultats cliniques et ont analysé le dossier du patient et les notes de l'opération. Ils ont colligé les mesures des résultats cliniques, y compris le taux de prise de la greffe, les complications et la nécessité d'une nouvelle opération. RÉSULTATS: Douze patients d'un âge moyen de 38 ans (plage de 15 à 66 ans) ont subi la technique de greffe Meek. Le pourcentage moyen de la surface corporelle totale brûlée était de 54,3 % (plage de 31 % à 77 %). Ainsi, 83 % des zones greffées ont bien guéri et n'ont nécessité aucune nouvelle greffe. Dans les 17 % de zones restantes, l'infection et l'hématome étaient les principales causes d'échec de la greffe. CONCLUSIONS: La technique de greffe Meek est une approche opératoire rapide et efficace pour couvrir de peau des brûlures pleine épaisseur étendues lorsque les sièges d'autogreffe sont limités.

Carbon monoxide intoxication: What we know.

Carbon monoxide (CO) is a toxic, color-, taste- and odorless gas with fatal consequences if undetected. Intoxication caused by CO is frequent possibly leading to a high morbidity and mortality. The disease involves multiple organ systems without a typical clinical presentation. The clinical picture is furthermore unrelated to levels of carboxyhemoglobin - the routine biomarker. Therefore the diagnosis and treatment can be very demanding. This article in detail reviews epidemiology, symptoms, diagnosis and the therapy of this multidisciplinary challenge.

Role of Wnt signaling during inflammation and sepsis: A review of the literature.

Despite the development of modern intensive care and new antimicrobial agents, the mortality of patients with severe sepsis and septic shock remains high. Systemic inflammation is a consequence of activation of the innate immune system. It is characterized by the intravascular release of proinflammatory cytokines and other vasoactive mediators, with concurrent activation of innate immune cells. The Wnt signaling pathway plays a critical role in the development of multicellular organisms. Abnormal Wnt signaling has been associated with many human diseases, ranging from inflammation and degenerative diseases to cancer. This article reviews the accumulating evidence that the Wnt signaling pathway plays a distinct role in inflammation and sepsis.

[Management of severe sepsis using a Cytokin-adsorber]. / Management einer schweren Sepsis unter Einsatz eines Zytokin-Adsorbers.

Based on a representative case, which was treated in our center for severe burn injuries, the severity of the Waterhouse-Friderichsen syndrome and the complexity of the prolonged course of treatment are illustrated. Special attention is focused on the new treatment paradigm using the CytoSorb® adsorber.