Assessing the behavior of a hybrid model of the knee with contact surrogate under parameter uncertainties.

Modeling the knee is an important factor in increasing the quality of life of both healthy individuals and patients. Nevertheless, the intricate nature of the knee makes this problem complicated. In this study, an extension to an established planar knee joint model with Hertzian contact pairs is proposed with contact mechanics based on polynomial chaos expansion surrogate. Firstly, the finite element (FE) model is made representing a contact pair of sphere-to-plane type with two layers on both bodies, corresponding to the cartilage and the bone. Five variables corresponding to both geometry and material parameters are used to parametrize this model. Then, 128 distinct variants of the FE model are created based on a quasi-Monte Carlo sequence. This dataset is used to train and validate the surrogate. The trained surrogate is proven to have predictive capabilities with an average nRMSE of 0.2% in randomized test/train splits. When included in a model of the knee and tested under parameter uncertainties in Monte Carlo simulations, it results in nRMSE of 58% for angular coordinate compared to the original model with Hertzian pair. This signifies the high influence of contact formulation on the model output and the need for more physically based models in knee contact modeling.

Immunogenetic Aspects of Sarcopenic Obesity.

Sarcopenic obesity (SO) is a combination of obesity and sarcopenia, with diagnostic criteria defined as impaired skeletal muscle function and altered body composition (e.g., increased fat mass and reduced muscle mass). The mechanism of SO is not yet perfectly understood; however, the pathogenesis includes aging and its complications, chronic inflammation, insulin resistance (IR), and hormonal changes. Genetic background is apparent in the pathogenesis of isolated obesity, which is most often polygenic and is characterized by the additive effect of various genetic factors. The genetic etiology has not been strictly established in SO. Still, many data confirm the existence of pathogenic gene variants, e.g., Fat Mass and Obesity Associated Gene (FTO), beta-2-adrenergic receptor (ADRB2) gene, melanocortin-4 receptor (MC4R) and others with obesity. The literature on the role of these genes is scarce, and their role has not yet been thoroughly established. On the other hand, the involvement of systemic inflammation due to increased adipose tissue in SO plays a significant role in its pathophysiology through the synthesis of various cytokines such as monocyte chemoattractant protein-1 (MCP-1), IL-1Ra, IL-15, adiponectin or CRP. The lack of anti-inflammatory cytokine (e.g., IL-15) can increase SO risk, but further studies are needed to evaluate the exact mechanisms of implications of various cytokines in SO individuals. This manuscript analyses various immunogenetic and non-genetic factors and summarizes the recent findings on immunogenetics potentially impacting SO development.

Impact of Cardiac Magnetic Resonance on the Diagnosis of Left Ventricular Noncompaction-A 15-Year Experience.

The aim of this study was to assess the impact of cardiac magnetic resonance (CMR) on the diagnosis in patients with known or suspected left ventricular noncompaction (LVNC). We retrospectively reviewed the medical charts of 12,811 consecutive patients who had CMR studies between 2008 and 2022 in a large tertiary center. We included patients referred for CMR because of known or suspected LVNC. The study sample consisted of 333 patients, 193 (58.0%) male, median age 39.0 (26.8-51.0) years. Among 74 patients fulfilling the echocardiographic LVNC criteria, the diagnosis was confirmed in 54 (73.0%) cases. In 259 patients with ultrasound-based suspicion of LVNC, CMR led to an LVNC diagnosis in 82 (31.7%) patients. In both groups, CMR led to a new diagnosis in 89 cases (10 (13.5%) and 79 (30.5%)). A quantity of 38 (5.4%) patients were diagnosed with dilated cardiomyopathy, 11 (1.4%) patients were diagnosed with hypertrophic cardiomyopathy, and 21 (4.1%) patients were diagnosed with unclassified cardiomyopathy. In four patients with suspected LVNC, a myocardial trabeculation was a secondary result of dilatation due to coronary heart disease. In five cases, valvular heart disease was found. Four patients were diagnosed with athlete's heart. Other diagnoses (arrhythmogenic right ventricular cardiomyopathy, peripartum cardiomyopathy, hypokinetic non-dilated cardiomyopathy, sarcoidosis, amyloidosis, and ventricular septum defect) were found in six patients. CMR is a valuable tool in the evaluation of cardiac muscle and in differentiating LVNC and other cardiac diseases.

Breast Implant-Associated Anaplastic Large Cell Lymphoma: Where Hematology and Plastic Surgery Meet.

Breast implant insertion for breast reconstruction or breast augmentation is a developing procedure, with high demand worldwide-being the second most common plastic surgery in the US as of 2022. Breast-implant-associated anaplastic large cell lymphoma (BIA-ALCL) is T-cell, non-Hodgkin lymphoma, typically CD30+, ALK-, presenting with fluid collection in the inner aspect of the peri-implant capsule in most patients, with the onset exceeding 1-year after implantation. The mean time between breast implant insertion and BIA-ALCL development is 7-10 years. The main risk factor is the use of textured implants because of their susceptibility to triggering local inflammation and immune stimulation finally leading to lymphoproliferation. Genetic predispositions to hereditary breast cancer increase the risk of disease development as well. BIA-ALCL seems to be underestimated in many countries and the initial symptom-seroma might be overlooked and misdiagnosed. Despite its rarity, the awareness of the disease should be improved among patients and medical professionals. This paper summarizes epidemiology, etiopathogenesis, differential diagnosis, and treatment-both surgical and hematological approaches.

Identification of muscle movements and activity by experimental methods for selected cases - stage#1.

PURPOSE: The aim of this study was to determine the position where the most activated and isolated individual muscles were. In the next steps, the selected limb positions will be used to determine the maximum values of isometric forces of the individual muscle heads based on the Hill model. METHODS: In order to determine the sought muscle activation, an electromyograph was used. Isometric contraction measurements were carried out for seven series of tests. Isometric contraction was performed as 100% MVC. RESULTS: For the long head of the biceps muscle, in the case of bending in the shoulder joint, angle of 75° was selected and for abduction in the shoulder joint - 90°. Internal rotation in the shoulder joint was omitted because of lower activation values. For the short head of the biceps muscle, the angle characterized by the greatest activity of the head was the angle of 115° in flexion at the elbow joint. The selected angle was 30° for shoulder extension and 110° for shoulder adduction. For the lateral head of the triceps brachial muscle, measurements showed that the angle at which the lateral head was most activated is 115°. CONCLUSIONS: The aim of this study was to determine the positions of the arm muscles that activate and isolate individual heads the most. The research presented and achieved results concern one specific person for whom a personalized numerical model was developed to represent the flexion-extension movement at the elbow joint. The performed tests can also be a preliminary assessment of the upper limb positions, for which wider conclusions could be drawn in the case of measurements on a larger number of participants.