Musculoskeletal models based on multibody dynamics have been widely applied in human biomechanics research; however, conventional one-dimensional (1D) muscle models are limited in their ability to represent realistic muscle geometry and fiber architecture, resulting in restricted biomechanical predictions. Although three-dimensional (3D) finite element (FE) muscle models can provide more detailed mechanical information, high computational cost limits their application at the whole lower-limb scale. To address these limitations, this study develops a unilateral lower-limb musculoskeletal model with hybrid muscles based on the TLEM2.0 database, in which the soleus-gastrocnemius muscle group was represented using 3D FE models, while the remaining muscles were modeled using 1D Hill-type formulations. By coupling FE analysis with muscle recruitment optimization, muscle activation patterns of the right lower limb during the stance phase of level walking were obtained. Model predictions were validated against in vivo knee joint reaction forces and surface electromyography (sEMG) data. The results demonstrated good agreement between the predicted and experimentally measured knee joint reaction forces, and the predicted force patterns of the medial and lateral gastrocnemius muscles corresponded well with sEMG trends. In addition, the model enabled detailed observation of muscle deformation as well as internal tensile stress and strain distributions in the 3D muscles during gait. This hybrid musculoskeletal modeling framework achieves a balance between computational efficiency and biomechanical fidelity, providing an effective platform for investigating lower-limb muscle biomechanics.
Optical coherence tomography angiography (OCTA) is an emerging non-invasive ophthalmic imaging modality. The morphology and contour of the foveal avascular zone (FAZ) are critical biomarkers for the diagnosis of various ophthalmic and systemic diseases; therefore, achieving its accurate segmentation is of substantial clinical significance. To address challenges such as low contrast, indistinct boundaries, and structural confusion with the surrounding retinal vasculature in OCTA images, this paper proposes a multi-scale dilated convolution and dual attention network (MSAD-Net). By integrating a multi-scale dilated convolution module (MSDM) to capture extensive multi-scale contextual information and employing a dual attention module (DAM) to integrate complementary channel and spatial features, thereby synergistically boosting the feature representation of key regions. Experimental results demonstrated that the model achieved superior performance and robust generalization across multiple evaluation metrics, including the Dice similarity coefficient, Jaccard index, precision, and recall-on two public datasets. These findings confirm the robustness of MSAD-Net in the fine segmentation of the FAZ, providing high-precision technical support for the clinical quantitative analysis of ophthalmic diseases.
Articular surface conformity is a critical factor influencing the biomechanics of knee prostheses, yet its impact on the biomechanics of rotation-hinged knee (RHK) prostheses and their tibial fixation remains unclear. In this study, a rotational platform tibial insert model of RHK prostheses with varying coronal and sagittal conformities is established. Finite element analysis was performed under ISO boundary conditions to investigate the effects of articular surface conformity on the biomechanics of the RHK prosthesis and tibial fixation. The study revealed that when the coronal conformity decreased from 0.83 to 0.33, the maximum Mises stress in the tibia and the maximum contact pressure in the insert increased by 10.78% and 52.62%, respectively, while the maximum shear stress in the bone cement decreased by 10.17%. When sagittal conformity decreased from 0.88 to 0.47, the maximum Mises stress in the tibia and maximum contact pressure in the insert increased by 5.62% and 14.31%, respectively, while Mises stress at the hinge-rotation axis and bone cement shear stress decreased by 62.53% and 29.46%, respectively. A reduction in conformity decreased the contact area. Sagittal conformity has a lesser impact on insert contact pressure compared to coronal conformity, but a more significant impact on bone cement shear stress, and reducing sagittal conformity could effectively reduce the Mises stress at the hinge-rotation axis. The coronal conformity of the RHK prosthesis on the rotational platform more effectively regulates contact mechanics, reducing sagittal conformity facilitates lowering hinge-rotation axis Mises stress and bone cement shear stress without significantly increasing contact pressure, thereby mitigating risks of prosthesis failure such as dislocation, fracture, and loosening.
Peritoneal dialysis serves as a critical treatment modality for end-stage renal disease. Extensive clinical practice has demonstrated that long-term exposure to high-glucose non-physiological peritoneal dialysis solutions can induce peritoneal injury, which is directly associated with a decline in ultrafiltration function and solute clearance capacity. This represents a significant cause of technical failure in dialysis and adverse clinical outcomes, such as peritonitis. Mesothelial cells and the glycocalyx on their surface, acting as the direct barrier between the peritoneum and the dialysis solution, play essential roles in regulating multiple pathophysiological processes, including fibrosis and inflammation, and are crucial for maintaining peritoneal function. This review provides a brief introduction to mesothelial cells and the glycocalyx, with a focus on elucidating the injury to the mesothelium and glycocalyx caused by high-glucose non-physiological peritoneal dialysis solutions, the associated injury mechanisms, and potential protective strategies. The aim is to offer insights for developing novel therapeutic approaches to preserve the structural and functional integrity of the peritoneum and extend the survival of patients undergoing peritoneal dialysis.
In minimally invasive surgery, surgical instruments must enter the human body through channels with diameters of only a few millimeters to perform collaborative operations in narrow, unstructured spaces with uncertain morphologies. This presents challenges for real-time safe collaborative control due to the high risk of collisions and the high redundancy of the system. To address these challenges, a cooperative motion control method based on hybrid multi-stage optimization for ultra-minimally invasive dual-arm continuum surgical robots is proposed. First, the continuum manipulators and the environment were geometrically characterized by parametric spatial curves and voxel grid downsampling, respectively, to establish a collision detection model. Second, the Hybrid Multi-Stage Optimization with Dynamic Weight Adaptation (HMSO-DWA) algorithm was proposed. A dynamic weight objective function, based on minimum distance, was designed with a view to achieving an adaptive balance between the priorities of obstacle avoidance and task tracking. Additionally, an active safety intervention mechanism was introduced to execute strong avoidance while retaining weak target guidance under extreme risks. Simulation results showed that the collaborative task success rate reached 98.7% under dynamic obstacle interference, and the minimum inter-arm distance was maintained above 3.28 mm. Prototype experiments indicated that the tracking errors of the two arms were (0.444 ± 0.326) mm and (0.418 ± 0.273) mm, respectively. The proposed method effectively achieves safe collaborative control and trajectory tracking in constrained environments.
