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Graph transformer has achieved remarkable success in graph‐based segmentation tasks. Inspired by this success, we propose a novel method named MeshFormer for applying the graph transformer to the semantic segmentation of high‐resolution meshes. The main challenges are the large data size, the massive model size, and the insufficient extraction of high‐resolution semantic meanings. The large data or model size necessitates unacceptably extensive computational resources, and the insufficient semantic meanings lead to inaccurate segmentation results. MeshFormer addresses these three challenges with three components. First, a boundary‐preserving simplification is introduced to reduce the data size while maintaining the critical high‐resolution information in segmentation boundaries. Second, a Ricci flow‐based clustering algorithm is presented for constructing hierarchical structures of meshes, replacing many convolutions layers for global support with only a few convolutions in hierarchy structures. In this way, the model size can be reduced to an acceptable range. Third, we design a graph transformer with cross‐resolution convolutions, which extracts richer high‐resolution semantic meanings and improves segmentation results over previous methods. Experiments show that MeshFormer achieves gains from 1.0% to 5.8% on artificial and real‐world datasets. [ABSTRACT FROM AUTHOR]

Accurate and reliable segmentation of colorectal tumors and surrounding colorectal tissues on 3D magnetic resonance images has critical importance in preoperative prediction, staging, and radiotherapy. Previous works simply combine multilevel features without aggregating representative semantic information and without compensating for the loss of spatial information caused by down-sampling. Therefore, they are vulnerable to noise from complex backgrounds and suffer from misclassification and target incompleteness-related failures. In this paper, we address these limitations with a novel adaptive lesion-aware attention network (ALA-Net) which explicitly integrates useful contextual information with spatial details and captures richer feature dependencies based on 3D attention mechanisms. The model comprises two parallel encoding paths. One of these is designed to explore global contextual features and enlarge the receptive field using a recurrent strategy. The other captures sharper object boundaries and the details of small objects that are lost in repeated down-sampling layers. Our lesion-aware attention module adaptively captures long-range semantic dependencies and highlights the most discriminative features, improving semantic consistency and completeness. Furthermore, we introduce a prediction aggregation module to combine multiscale feature maps and to further filter out irrelevant information for precise voxel-wise prediction. Experimental results show that ALA-Net outperforms state-of-the-art methods and inherently generalizes well to other 3D medical images segmentation tasks, providing multiple benefits in terms of target completeness, reduction of false positives, and accurate detection of ambiguous lesion regions. [ABSTRACT FROM AUTHOR]

Aim To study the character of blood circulation in the bone stump at tight and loose closure of the medullary cavity. Methods Two series of experiments on 39 rabbits with mid-third femoral amputation and muscular plasty were carried out. In the 1st (experimental) series, the bone scapula was closed by thin cortical autograft taken from the epimetaphyseal area, and then the muscles were sutured, and in the 2nd -- the scapula was closed by myoplasty only. Follow-up periods: 1st series -- 7, 14, 21 days and 1, 3, 6 months, 2nd series -- 1, 3, 6 months. Histological methods with infusion of vessels with ink-gelatin mixture and morphometry was used. Results In the 1st series there was a rapid restoration of the disturbed macro- and microcirculation due to the reserve sources of blood circulation and the development of extravascular ways of microcirculation. In the 2nd series, blood circulation recovery was significantly slower and occurred mainly due to the development of extravascular microcirculatory pathways. Conclusion The study established undeniable usefulness of tight closure of the bone marrow cavity during amputation. [ABSTRACT FROM AUTHOR]

Aim To investigate rehabilitation outcomes of patients with malformed tibial stumps. Methods Observations included 421 patients with residual limb diseases and malformations (extensive inactive scars adhered to the bone, excessively long or short stumps, bone filing, osteomyelitis of the stump, muscle attachment to the skin scar, excessive mobility and deviations of the fibula, improper filing). Four hundred and thirty-six (436) reconstructive surgeries were performed. A follow-up period was from 6 months to 15 years. Radiological, ultrasonic, tensometrical, and histological methods were used. Results Due to the frequent combination of several malformations and diseases in the same patient, non-free skin grafting with displaced dermal-subcutaneous flaps, which cover rather large defects, was widely used. The surgeries were performed simultaneously and allowed for reconstruction without shortening the bone lever stump. Complications in the form of marginal necrosis were obtained in three (0.71%) patients. The improved technique of muscle grafting with the fixation of muscles to the bone provided an elastic stump covering the bone filing. The authors have developed original methods of surgery to create a bone block of the tibia, which make it possible to obtain painless, highly functional stumps using partial support and ensure long-term use of modern prosthesis designs in 100% of cases. Conclusion Non-free dermal plasty with cutaneous-subcutaneous flap is the method of choice for closing skin defects on the residual limb. Muscle-bone fixation permits to eliminate some residual limb defects and to form an elastic muscular residual limb with closed bone filaments. Synostosis formation in different ways considerably improves functional quality of the residual limb. [ABSTRACT FROM AUTHOR]

Aim To investigate the effect of direct epineural electrical stimulation of the nerve on the nature of reparative processes in the bone stump. Methods Three series of experiments were carried out with amputation of the thigh in the middle third and muscle plasty. In the 1st and 2nd experimental series a perineural catheter was brought to the stump of the sciatic nerve, through which mechanical irritation of the nerve was performed for 20 days daily for 20 minutes. In the 2nd series, an electrode was added to the nerve and epineural electrical stimulation was performed daily for 20 days. Animals of the 3rd series served as control. The observation periods were 1, 3, 6 months. Histological research method with filling vessels with ink-gelatin mixture was applied. Results In the 1st series, there was a sharp distortion of the reparative process, which consisted of a violation of microcirculation, changes in shape, resorption of the cortical diaphyseal plate, fractures, deformations. In most experiments of the 2nd series, organotypic stumps were formed with normalization of microcirculation. In the 3rd series, results of the formation of the stump were better than in the 1st, but worse than in the 2nd series. Conclusions Painful nerve irritation after amputation leads to a significant disturbance of microcirculation and reparative regeneration at the end of the bone stump with the development of pathological restructuring of bone tissue. Electrostimulation of the nerve improves microcirculation and reparative regeneration of the bone tissue., (Copyright© by the Medical Assotiation of Zenica-Doboj Canton.)

Objective: The aim: To study the influence of biomechanical factors on the character of morphological disorders in the process of reparative regeneration at the end of the residual limb after amputation., Patients and Methods: Materials and methods: 10 series of experiments on 144 rabbits were conducted. We used myodesis with normal, insufficient and excessive muscle tension, their electrical stimulation, tight and leaky closure of the bone marrow canal. Terms of observation 1, 3, 6 months. The method of research - histological with the filling of vessels with inkgelatin mixture., Results: Results: Dense closure of the meduallary cavity and uniform muscle tension during plasty in the first three series of experiments allow to obtain a cylindrical residual limb with preservation of the cortical diaphyseal plate, formation of the bone closing plate, normalization of intraosseous microcirculation, completion of the reparative process. In the majority of observations of the IV-X series there was a reparative regeneration disorder connected with the incorrect tension of muscles and the absence of normalization of intraosseous circulation, the reparative process was not observed to be complete, which led to the pathological reorganization of bone tissue with the formation of stumps of various shapes., Conclusion: Conclusions: Uneven muscle tension and lack of closure of the intramedually canal except for microcirculation disorders leads to increased periosteum bone formation, formation of periosteum cartilage exostases, clavate stumps, resorption and fractures of the cortical diaphyseal plate with curvature and stump axis disorders, formation of a conical stump.