Computational models of bone fracture healing and applications: a review.

Fracture healing is a very complex physiological process involving multiple events at different temporal and spatial scales, such as cell migration and tissue differentiation, in which mechanical stimuli and biochemical factors assume key roles. With the continuous improvement of computer technology in recent years, computer models have provided excellent solutions for studying the complex process of bone healing. These models not only provide profound insights into the mechanisms of fracture healing, but also have important implications for clinical treatment strategies.

mResU-Net: multi-scale residual U-Net-based brain tumor segmentation from multimodal MRI.

Brain tumor segmentation is an important direction in medical image processing, and its main goal is to accurately mark the tumor part in brain MRI. This study proposes a brand new end-to-end model for brain tumor segmentation, which is a multi-scale deep residual convolutional neural network called mResU-Net. The semantic gap between the encoder and decoder is bridged by using skip connections in the U-Net structure.

Improved adaptive tessellation rendering algorithm.

Background: The human body model in the virtual surgery system is generally nested by multiple complex models and each model has quite complex tangent and curvature change. In actual rendering, if all details of the human body model are rendered with high performance, it may cause the stutter due to insufficient hardware performance. If the human body model is roughly rendered, the details of the model cannot be well represented.

An Automatic Segmentation Method for Lung Tumor Based on Improved Region Growing Algorithm.

In medical image processing, accurate segmentation of lung tumors is very important. Computer-aided accurate segmentation can effectively assist doctors in surgery planning and treatment decisions. Although the accurate segmentation results of lung tumors can provide a reliable basis for clinical treatment, the key to obtaining accurate segmentation results is how to improve the segmentation performance of the algorithm.

A novel virtual cutting method for deformable objects using high-order elements combined with mesh optimisation.

Background: Virtual cutting of deformable objects plays an important role in many applications, especially in digital medicine, such as soft tissue cutting in virtual surgery training system.

Methods: We developed a novel virtual cutting algorithm, combined with mesh optimisation. A new local mesh processing method is used to control the number and quality of the elements created during the cutting process.

Multiscale modeling of skeletal muscle to explore its passive mechanical properties and experiments verification.

The research of the mechanical properties of skeletal muscle has never stopped, whether in experimental tests or simulations of passive mechanical properties. To investigate the effect of biomechanical properties of micro-components and geometric structure of muscle fibers on macroscopic mechanical behavior, in this manuscript, we establish a multiscale model where constitutive models are proposed for fibers and the extracellular matrix, respectively. Besides, based on the assumption that the fiber cross-section can be expressed by Voronoi polygons, we optimize the Voronoi polygons as curved-edge Voronoi polygons to compare the effects of the two cross-sections on macroscopic mechanical properties.

An efficient method to improve the quality of tetrahedron mesh with MFRC.

In this paper, we proposed a novel operation to reconstruction tetrahedrons within a certain region, which we call MFRC (Multi-face reconstruction). During the existing tetrahedral mesh improvement methods, the flip operation is one of the very important components. However, due to the limited area affected by the flip, the improvement of the mesh quality by the flip operation is also very limited.

Modeling and simulation of excitation- contraction coupling of fast-twitch skeletal muscle fibers.

Background: The current excitation-contraction coupling model of fast-twitch skeletal muscle fibers cannot completely simulate the excitation-contraction process.

Objective: To solve this problem, this study proposes an excitation-contraction model of fast-twitch skeletal muscle fibers based on the physiological structure and contractile properties of half-sarcomeres.

Methods: The model includes the action potential model of fast-twitch fiber membranes and transverse tubule membranes, the cycle model of 𝐶𝑎2+ in myofibril, the cross-bridge cycle model, and the fatigue model of metabolism.

A review of computer-assisted orthopaedic surgery systems.

Background: Computer-assisted orthopaedic surgery systems have great potential, but no review has focused on computer-assisted surgery systems for the spine, hip, and knee.

Methods: A systematic search was performed in Web of Science and PubMed. We searched the literature on computer-assisted orthopaedic surgery systems from 2008 to the present and focused on three aspects of systems: training, planning, and intraoperative navigation.

Label fusion method combining pixel greyscale probability for brain MR segmentation.

Multi-atlas-based segmentation (MAS) methods have demonstrated superior performance in the field of automatic image segmentation, and label fusion is an important part of MAS methods. In this paper, we propose a label fusion method that incorporates pixel greyscale probability information. The proposed method combines the advantages of label fusion methods based on sparse representation (SRLF) and weighted voting methods using patch similarity weights (PSWV) and introduces pixel greyscale probability information to improve the segmentation accuracy.

Mechanical Respond and Failure Mode of Large Size Honeycomb Sandwiched Composites under In-Plane Shear Load.

The present work focuses on the in-plane shear respond and failure mode of large size honeycomb sandwich composites which consist of plain weave carbon fabric laminate skins and aramid paper core. A special size specimen based on a typical element of aircraft fuselage was designed and manufactured. A modified in-plane shear test method and the corresponding fixture was developed.

Multi-atlas active contour segmentation method using template optimization algorithm.

Background: Brain image segmentation is the basis and key to brain disease diagnosis, treatment planning and tissue 3D reconstruction. The accuracy of segmentation directly affects the therapeutic effect. Manual segmentation of these images is time-consuming and subjective.

A review of virtual cutting methods and technology in deformable objects.

Background: Virtual cutting of deformable objects has been a research topic for more than a decade and has been used in many areas, especially in surgery simulation.

Methods: We refer to the relevant literature and briefly describe the related research. The virtual cutting method is introduced, and we discuss the benefits and limitations of these methods and explore possible research directions.

Three-dimensional computational model simulating the fracture healing process with both biphasic poroelastic finite element analysis and fuzzy logic control.

A dynamic model regulated by both biphasic poroelastic finite element analysis and fuzzy logic control was established. Fuzzy logic control was an easy and comprehensive way to simulate the tissue differentiation process, and it is convenient for researchers and medical experts to communicate with one another to change the fuzzy logic rules and improve the simulation of the tissue differentiation process. In this study, a three-dimensional fracture healing model with two different interfragmentary movements (case A: 0.

Development and application of computer assisted optimal method for treatment of femoral neck fracture.

Background: To help doctors decide their treatment from the aspect of mechanical analysis, the work built a computer assisted optimal system for treatment of femoral neck fracture oriented to clinical application.

Objective: The whole system encompassed the following three parts: Preprocessing module, finite element mechanical analysis module, post processing module.

Methods: Preprocessing module included parametric modeling of bone, parametric modeling of fracture face, parametric modeling of fixed screw and fixed position and input and transmission of model parameters.

High-quality mesh generation for human hip based on ideal element size: methods and evaluation.

The objective of this work was to obtain high-quality mesh generation results for the human hip. This study adopted an edge-collapse algorithm based on quadric error metrics to simplify the hip model. The adjacent triangular areas and a cost function that considered the mean value of error were introduced to avoid error accumulation and ensure invariant geometric features.

A review of computational models of bone fracture healing.

In the process of fracture healing, there are many cellular and molecular events that are regulated by mechanical stimuli and biochemical signals. To explore the unknown mechanisms underlying bone fracture healing, optimal fixation configurations, and the design of new treatment strategies, computational healing models provide a good solution. With the simulation of mechanoregulatory healing models, bioregulatory healing models and coupled mechanobioregulatory healing models, healing outcomes can be predicted.

A review of bioregulatory and coupled mechanobioregulatory mathematical models for secondary fracture healing.

Fracture healing is a complex biological process involving many cellular and molecular events. During fracture healing, biochemical signals play a regulatory role in promoting the healing process. Although many experiments have been conducted to study fracture healing, not all of the mechanisms are clearly understood.

A novel modelling and simulation method of hip joint surface contact stress.

Understanding the hip joint surface contact stress distribution characteristics is helpful to determine hip joint biomechanical features and abnormal pathological behavior. Firstly, a 3-dimensional static hip joint biomechanical model is built using analytical method of model in order to study biomechanical properties including bearing area, stress distribution and the peak value of the contact stress of the femoral head, which reveals the relationship between the biomechanical properties and its geometric parameters. Secondly, based on the finite element analysis of the hip joint model, the contact stress distribution on the surface of femoral head is acquired under the condition of the different joint force and the acetabulum coverage rate.

BMP7 enhances the effect of BMSCs on extracellular matrix remodeling in a rabbit model of intervertebral disc degeneration.

Intervertebral discs (IVDs) provide stability and flexibility to the spinal column; however, IVDs, and in particular the nucleus pulposus (NP), undergo a degenerative process characterized by changes in the disc extracellular matrix (ECM), decreased cell viability, and reduced synthesis of proteoglycan and type II collagen. Here, we investigated the efficacy and feasibility of stem cell therapy using bone marrow mesenchymal stem cells (BMSCs) over-expressing bone morphogenetic protein 7 (BMP7) to promote ECM remodeling of degenerated IVDs. Lentivirus-mediated BMP7 over-expression induced differentiation of BMSCs into an NP phenotype, as indicated by expression of the NP markers collagen type II, aggrecan, SOX9 and keratins 8 and 19, increased the content of glycosaminoglycan, and up-regulated β-1,3-glucuronosyl transferase 1, a regulator of chondroitin sulfate synthesis in NP cells.

Anatomically Based Geometric Modelling Using Medical Image Data: Methods and Programs.

The human organs geometric modeling software which can achieve two-dimensional medical image browsing, pretreatment and three dimensional (3D) reconstruction in this paper is designed. This software implements medical image segmentation using the method combining the region growing and the interactive segmentation. Also, the MC surface reconstruction algorithm is utilized to achieve the three-dimensional reconstruction.

A novel finite element method based biomechanical model for HIT-robot assisted orthopedic surgery system.

To build a biomechanical human model can make much sense for surgical training and surgical rehearse. Especially, it will be more meaningful to develop a biomechanical model to guide the control strategy for the medical robots in HIT-Robot Assisted Orthopedic Surgery System (HIT-RAOS). In this paper, based the successful work of others, a novel reliable finite element method based biomechanical model for HIT-RAOS was developed to simulate the force needed in reposition procedure.

A novel finite element method based biomechanical model for HIT-Robot Assisted Orthopedic Surgery System.

To build a biomechanical human model can make much sense for surgical training and surgical rehearse. Especially, it will be more meaningful to develop a biomechanical model to guide the control strategy for the medical robots in HIT-Robot Assisted Orthopedic Surgery System (HIT-RAOS). In this paper, based the successful work of others, a novel reliable finite element method based biomechanical model for HIT-RAOS was developed to simulate the force needed in reposition procedure.