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Abstract:Ear and upper airway are portal organs of human body. Because of their fine and narrow structure, the non-invasive research and the effect of clinical diagnosis and treatment in traditional medicine are always unsatisfactory. With the development of computer technology, numerical simulation has become an effective means of auxiliary research. Numerical simulation can reproduce or evaluate the diagnosis and treatment of ear and upper airway diseases, and it is a powerful means to promote the development of basic medicine and technology of clinical diagnosis and treatment. The application of numerical simulation in relationship between the structure and function of ear and upper airway, the influence of diseases on function, the evaluation of clinical diagnosis and treatment technology， as well as the design of related medical devices were reviewed. The clinical application of numerical research in ear and upper airway was prospected, so as to provide references for the future clinical diagnosis and treatment of ear and upper airway.

Abstract:Objective To study the relationship between pulsatile tinnitus and temporal bone pneumatization grade. Methods Through the in vitro experiment, the generation and transmission pathways of the venous sound were simulated. The sound signals at the position of eardrum were recorded and analyzed. Results In case of cortical plate dehiscence, the high pressure and pulse-synchronous venous sounds were received at eardrum. The highest sound pressure occurred in the normal pneumatization case. In case of cortical plate intactness, the non-pulsatile venous sounds with pressure close to the background control sound were received at eardrum. Temporal bone air cells (TBAC) with different pneumatization grades would transmit venous sound in different frequency ranges. Conclusions Normal pneumatization TBAC exhibited the highest amplification on venous sound, while hypopneumatization TBAC exhibited the lowest amplification on venous sound. The pneumatization grade of TBAC is neither the sufficient nor essential condition of pathogenic venous sound, while the cortical plate dehiscence is the sufficient or necessary condition of pathogenic venous sound.

Abstract:Objective To study the influence of middle ear malformation on the performance of round window stimulation, so as to provide references for optimization of the round window stimulation middle ear implant. Methods The finite element model of human ear including an asymmetrical two-cavity non-helical cochlea was constructed and compared with experimental data to verify reliability of the model. Based on this model, the effects of three kinds of middle ear malformation, i.e., ossicular chain fixation, ossicular chain fusion and ossicular defect on round window stimulation were simulated by changing material properties of the corresponding tissues. Results The middle ear malformation mainly affected the low-frequency performance of round window stimulation. The ossicular chain fixation and the ossicular chain fusion had a deteriorating effect on round window stimulation. The stapes fixation had the greatest effect on the performance of round window stimulation, with the reduction as high as 47.93 dB. Ossicles defects could improve the performance of round window stimulation, with the maximum increment of 6.24 dB. Conclusions The middle ear malformation had an effect on the low frequency performance of round window stimulation. It is necessary to specifically increase output of the actuator when implanting the round window stimulation middle ear implant.

Abstract:Objective To explore the effects of different skull-brain interfaces and mesh density of the cerebrospinal fluid (CSF) on dynamic responses of the brain. Methods The impact kinematics on cadaver head under rotation and translation impacts were reconstructed based on the 50th percentile adult head finite element model. The interfaces between skull and CSF, CSF and brain were modeled with different types of interfaces, which were set as sharing nodes, tied, frictionless sliding, so as to investigate the effect of different interface types on dynamic responses of the brain. Then, the interfaces between CSF, skull and brain were set as sharing nodes, while CSF was divided into single-layer and tri-layer of hexahedral element with the constant thickness of CSF, to study influences of CSF with different mesh density layers on dynamic responses of the brain. Results The intracranial pressure was highly sensitive to the interface types, while the brain response seemed to be relatively insensitive to the variation in CSF layers. Conclusions The research findings provide theoretical references for the construction of CSF and the selection of skull-brain contact interface of the head finite element model.

Abstract:Objective By developing an automatic procedure for optimization of femoro-tibial contact area for knee prosthesis, to summarize the influence pattern of design parameters on contact area, and discover the relationship between the maximum contact stress and contact area. Methods A parametric finite element (FE) model was developed in the Isight software, which included three components: automatic parameter changes for the geometric model, automatic modeling in the FE software, and automatic FE calculation. The automatic workflow was realized, and then contact areas were statistically analyzed. Results The FE model was validated by using Tekscan pressure distribution system. When the femoral sagittal radius was gradually close to the tibial sagittal radius, the contact area gradually reached to the maximum 295 mm2. The femoral sagittal radius had a positive effect on contact area, while the tibial sagittal radius had a negative effect. The maximum contact stress had a linear relationship with contact area approximately. Conclusions This study analyzed the influence of femoro-tibial sagittal radius on contact stress and contact area, and the research findings would provide references for the design on reducing wear of tibial insert in clinic.

Abstract:Objective To compare differences in mechanical stability of intramedullary fibular allograft with cannulated screw (modified method) and cannulated screw alone (conventional method) for fixing young and middle-aged Pauwels Ⅰ, Ⅱ, Ⅲ femoral neck fractures. Methods Models of Pauwels Ⅰ, Ⅱ, Ⅲ femoral neck fracture fixed by conventional method and modified method were constructed. Stress distributions on weight-bearing area of the femoral cortical bone shell and the end of femoral neck fracture, as well as shear stress distributions on cortical bone shell of the femoral head and femoral neck fracture surface were analyzed, the maximum principal strain cloud maps of the femur in coronal position were drawn according to the predicted data, and the displacements of femoral neck fracture end between two groups were compared. Results The shear stress distributions on cortical bone shell of the femoral head in two directions (S12, S13) showed that femoral neck fractures fixed by modified method was superior or close to that by conventional method. Besides, the shear stress distributions on fracture surface of the femoral neck in two directions (S12, S23) showed that modified internal fixation was superior to conventional internal fixation. The displacements of femoral neck fracture end in Pauwels Ⅱ and Ⅲ fracture fixed by conventional method were greater than those by modified method and the displacements of Pauwels Ⅱ fracture fixed by conventional method were obviously larger than those of Pauwels Ⅱ fracture fixed by modified method. But Pauwels Ⅰ fracture fixed by modified method showed a larger displacement than that fixed by conventional method. Conclusions Modified method is more suitable for fixing femoral neck fracture with large angles (Pauwels Ⅱ and Ⅲ fracture), and conventional method is more suitable for fixing neck fracture with small angles (Pauwels Ⅰ fracture).

Abstract:Objective To establish a personalized musculoskeletal multi-body dynamics model of total knee replacement (TKR) by two software nmsBuilder and OpenSim, and verify this established model by using bouncy and medthrust gait patterns. Methods Based on skeletal data from a patient, the body, skeletal landmark clouds and muscular landmark clouds were established for automatically generating reference systems and muscles. The musculoskeletal model generated by nmsBuilder was introduced into OpenSim, and inverse kinematics, static optimization and knee joint force analysis were performed successively. Finally, the model was driven by bouncy gait and medthrust gait respectively, and the results were compared with experimental measurements. Results Except for the lateral joint contact forces, the predicted magnitude and trend of knee joint contact forces by the model had a good agreement with the experimental data, and the constructed skeletal muscle multi-body dynamics model could be used for knee joint research. Conclusions The established musculoskeletal multi-body dynamics model could predict the medial, lateral and total tibiofemoral joint contact forces simultaneously by inputting the marker positions and the ground reaction forces. The research ideas of this study can provide references for designing personalized knee prostheses for TKR patient.

Abstract:Objective To investigate the biomechanical behavior of porous scaffold with different materials (Ti, Ta, PEEK, HA) for repairing rabbit femur defects under immediate loading by three-dimensional finite element analysis (FEA), so as to explore the best porous scaffold material from the perspective of biomechanics. Methods The CBCT combined with software such as Mimics, SolidWorks, Geomagic Studio, ANSYS were used to establish an immediate loading model for the repair of rabbit femur defects with porous scaffolds at different stages of bone healing. The stress and strain distributions on the scaffolds and the surrounding tissues were calculated. Results The maximum equivalent stress of porous scaffold decreased along with the bone healing. In the granulation tissue and fibrous tissue model, the ratio of the maximum equivalent stress to the yield strength of porous scaffold was: HA＞Ta＞PEEK＞Ti. The maximum equivalent stress of the HA porous scaffold was greater than its yield strength. The number of suitable strain elements in tissues around the porous scaffolds was: PEEK＞Ta＞Ti＞HA. The number of potential fracture strain elements in tissues around the porous scaffolds was: HA＞Ta＞PEEK＞Ti. Conclusions The HA porous scaffold could not bear the immediate load and guide bone healing well under immediate loading. The elastic modulus of PEEK porous scaffold was similar to that of bone tissues, which could preferably guide bone healing. PEEK was an ideal porous scaffold material under immediate loading. The research findings provide

Abstract:Objective To construct a two-dimensional (2D) composite membrane and a three-dimensional (3D) biomimetic scaffold by silk fibroin (SF), type I collagen (Col-I) and hydroxyapatite (HA) blends in vitro, so as to study its physicochemical properties, as well as biocompatibility and explore the feasibility of its application in tissue engineering scaffold materials. Methods 2D composite membranes and 3D scaffolds were prepared by blending SF/Col-I/HA at the bottom of cell culture chamber and low temperature 3D printing combined with vacuum freeze drying. The biocompatibility was evaluated by mechanical property testing, scanning electron microscope and Micro-CT to examine the physicochemical properties of the material, and cell proliferation was detected to evaluate its biocompatibility. Results Stable 2D composite membrane and 3D porous structural scaffolds were obtained by blending and low temperature 3D printing. The mechanical properties were consistent. The pore size, water absorption, porosity and elastic modulus were all in accordance with the requirements of constructing tissue engineering bone. The scaffold was a grid-like white cube with good internal pore connectivity; HA was evenly distributed in the composite membrane, and the cells were attached to the composite membrane in a flat shape; the cells were distributed around pore walls of the scaffold. The shape of the shuttle was fusiform, and the growth and proliferation were good. Conclusions The composite membrane and 3D scaffold prepared by SF/Col-I/HA blending system had better pore connectivity and pore structure, which was beneficial to cell and tissue growth and nutrient transport. Its physicochemical properties and biocompatibility could meet the requirements of bone tissue engineering biomaterials.

Abstract:Objective To develop a novel electric stapler, so as to improve the automation, convenience and precision of minimally invasive surgery. Methods The clamping, firing and turning mechanism of the new electric stapler was innovatively designed to realize the electric drive of minimally invasive surgical anastomosis on the basis of traditional mechanical stapler. The motion process of electric clamping, firing and double-screw turning mechanism was analyzed in detail, and the equations for motion function of three mechanisms were solved, providing a theoretical basis for the intelligent control algorithm of electric stapler. Results The electric clamping and firing process was simulated using ADAMS software to verify the equation of motion. The prototype of the new electric stapler was made, and the anastomosis experiment and blasting pressure experiment of the in vitro small intestine tissues were carried out. The range of anastomotic blasting pressure was between 3.7 kPa and 11.67 kPa, meeting the basic requirements in clinic. Conclusions The structure of the new electric stapler can meet the requirements of electric pressing and firing in minimally invasive surgery, contributing to achieve tissue anastomosis more conveniently, quickly and effectively.

Abstract:Objective To improve the clinical application of using rehabilitation robot for hand rehabilitation and solve the current shortcomings of rigid hand rehabilitation robot, such as complex structure, heavy weight, potential safety hazard, a new soft and wearable robotic glove was proposed. Methods The robotic glove was driven by McKibben pneumatic artificial muscles (PAMs). The tendon drive system was designed based on simulation of human hand anatomy and physiology structure, which could transmit forces and torques through the user’s own skeleton and joints. The normal hand movement could be simulated and this design pattern highly reduced the weight of the robotic glove. Meanwhile a surface electromyogrphy (sEMG) collecting circuit was developed to acquire sEMG signals from the forearm. User intent could be detected by measuring the sEMG of flexor digitorum superficialis and extensor digitorum communis on the forearm. Results The results of the experiment investigation on characteristics of the soft robotic glove showed that the robotic glove could effectively assist people completing daily activities and grasping daily necessities. The feasibility and scientificity of the robotic glove was validated. Conclusions The soft and wearable robotic glove has an advantage of light weight, easy operation and high comfortableness, and it can provide references for the study and design of similar hand rehabilitation devices.

Abstract:Objective To establish a human activity recognition （HAR）model based on human activity signals obtained by built-in sensors of the mobile phone, so as to support daily physical state assessment, special population monitoring and other biomedical researches. Methods The mobile signal was collected using the mobile phone built-in sensor, and the public data set UCI HAR and WISDM were used as experimental data. The HAR model was established by using the feature extraction method combined with convolutional neural network and autoregressive model. Results The models all achieved more than 90% recognition accuracy in the self-collected dataset, UCI HAR and WISDM. Conclusions The introduction of autoregressive model can avoid the manual design eigenvalues and effectively reduce the computational complexity of large-scale stacked convolutional layers. The research findings prove that the method based on feature fusion can effectively recognize human activity.

Abstract:Objective To explore the changes in patellofemoral joint stress of lower limbs during curve running at a slower running speed, so as to analyze the possibility of increasing patellofemoral pain due to long curve running. Methods Newtest portable speed measurement system, Motion infrared high speed motion capture system, Kistler three-dimensional force plate were used to collect the kinematic parameters and ground reaction force from a total of 13 male college students without sports specialty at straight track and curve track (with inner diameter of 36 m) at the speed of (4.0±0.2) m/s. Results Compared with linear running, the patellofemoral joint stress at lateral side of the leg significantly increased during curve running. There were no significant differences in knee flexion angles and knee extensor moments when patellofemoral joint stress increased during curve running. Conclusions Long curve running is a contributing factor with respect to the development of patellofemoral pain in lateral leg and aggravating patellofemoral pain. It is suggested that running enthusiasts and patients with patellofemoral pain should avoid repeating long curve running.

Abstract:Extreme lateral interbody fusion (XLIF) can be used to treat various lumbar diseases, such as lumbar facet joints intervertebral disc herniation, spondylolisthesis, stenosis. Compared with other approaches, XLIF establishes the surgical channel behind the peritoneum through lateral abdomen, with the advantages of less blooding in the surgery, smaller invasion, lower complications rate and shorter rehabilitation period. Meanwhile，this technique can not only reduce the risk of vascular injury, but also avoid the damage of back structures，such as muscles and facet joints. Therefore, XLIF has been attracting more and more attention and application. However, there is no conclusive evidence to prove that XLIF is better than other surgical approaches in terms of clinical results and complications rates. This paper reviewed the effects of XLIF for reconstructing spinal stability, as well as its biomechanical properties compared with other classical surgeries.

Abstract:The importance of follower loads in maintaining spine biomechanics was described, and the various methods and means of follower load simulations of human spine specimens in vitro in recent years were summarized. By comparison with the real data of range of motion (ROM) and intervertebral disc pressure of human vertebral body, the feasibility of various simulation methods was analyzed from the perspectives of mechanics, and the optimal loading load and torque of human cervical, thoracic and lumbar vertebrae biomechanical experiments were summarized. The effects of conventional spinal internal fixation on biomechanical properties of the spine were also discussed.

Abstract:Extracellular matrix is the main element to provide mechanical clues for cells. The response of stem cells to mechanical signals is mainly achieved through the cytoskeleton. After mechanical signal is transmitted, cytoskeleton can form contractile microfilaments that actively generate tension through reorganization induced by microenvironment changes. The mechanical signals can regulate gene expression through either coupling with the nuclear skeleton directly or being transformed by the second message. Recent studies have proven that cytoskeleton tension has a series of impact on lineage specification, proliferation, differentiation and apoptosis of bone mesenchymal stem cells (BMSCs). BMSCs are of great significance in bone reconstruction and clinical treatment. The possible mechanisms about mechanotransduction and its effects of cytoskeleton tension on osteogenesis of BMSCs after micro-environmental changes were summarized.

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