Kinematics of hip,knee,ankle of the young and elderly Chinese people during kneeling activity

Objective:The purpose of this study was to measure the kinematics of the lower limbs of Chinese people during normal kneeling activity,as such data could be valuable in designing joint prosthesis and arthroplasty that meet the needs of Chinese citizens' daily activities.Methods:Thirty young and twenty elderly Chinese participants with no personal history of joint diseases were recruited,and matched by age(average age:23.8 years for the young group,60.8 years for the elderly group).Each participant performed six trials during which three-dimensional(3D) kinematics data were collected and the means of the 3D angles of the ankle,knee,and hip joints of two groups were calculated.Results:There were no obvious differences between the two groups in the knee and ankle joints.The mean range of knee flexion was 139.6° for the young group and 140.9° for the elderly group.The mean range of ankle flexion was 35.7° for the young group and 37.6° for the elderly group.The maximal eccentric flexion at the hip joint was 67.5° for the young group compared to 100.5° for the elderly group.Conclusions:The elderly uses more hip flexion angles than the young when assuming the kneeling posture.The ranges of motion obtained during kneeling activity are greater than the reported mean ranges of motion achieved following joint arthroplasty.The data could be valuable in establishing criteria for lower limb prosthetics and rehabilitation protocol for the Chinese population.

Motion performance and impingement risk of total hip arthroplasty with a simulation module

The present study introduced a new motion analysis method for total hip arthroplasty (THA). A motion simulation module of THA was designed and developed, which can simulate the THA’s implantation condition and motion and detect the theoretic range of motion (ROM) before the prosthetic component impingement happens.

Mechanical Behaviors of the Foot After Individual Releases of Plantar Fascia and Ligaments During the Balanced Standing

To quantify mechanical effects of plantar fascia and ligaments on the arch structure,a 3D finite element model of the foot was created to simulate the balanced standing posture. Four cases after individual releases of plantar fascia,spring ligament,long and short plantar ligaments were simulated respectively to compare their consequences to the predictions of the intact structure. It was founded that the foot arch didn't collapse obviously after any individual release of these structures. As plantar fascia was released,tensions of plantar ligaments were largely increased. Long and short plantar ligaments performed mutual compensation functions.

Research on Damage in Trabecular Bone of the Healthy Human Acetabulum at Small Strains Using Nonlinear Micro-finite Element Analysis

The mechanical properties of the pelvic trabecular bone have been studied at the continuum level. However, nothing is known about the tissue-level damage in the trabecular bone of the healthy human acetabulum at apparent small strains characteristic of habitual. By a DAWING 4000 A supercomputer, nonlinear micro-finite element (μFE) analysis was performed to quantify tissue-level damage accumulation in trabecular bone at small strains. The data indicate that damage in trabecular bone commence at 0.2% apparent strain. The findings imply that tissue yielding can initiate at very low strains in the trabecular bone of the healthy acetabulum and that this local failure has negative consequences on the apparent mechanical properties of trabecular bone.

Real-Time Deformation Simulation of Kidney Surgery Based on Virtual Reality

Virtual reality-based surgery simulation is becoming popular with the development of minimally invasive abdominal surgery,where deformable soft tissue is modelled and simulated.The mass-spring model(MSM)and finite element method(FEM)are common methods used in the simulation of soft tissue deformation.However,MSM has an issue concerning accuracy,while FEM has a problem with efficiency.To achieve higher accuracy and efficiency at the same time,we applied a co-rotational FEM in the simulation of a kidney with a tumour inside,achieving a real-time and accurate deformation simulation.In addition,we set a multi-model representation for mechanical simulation and visual rendering.The implicit Euler method and conjugate gradient method were adopted for setting and solving the linear system.For a realistic simulation of surgery,constraints outside the kidney and between the kidney and tumour were set with two series of mechanical properties for the two models.Experiments were conducted to validate the accuracy and real-time performance.

An automatic optimization method for minimizing supporting structures in additive manufacturing

The amount of supporting structure usage has been a major research topic in layer-based additive manufacturing(AM)over the past years as it leads to increased fabrication time and decreased surface quality.Previous studies focused on deformation and topology optimization to eliminate the number of support structures.However,during the actual fabrication process,the properties of shape and topology are essential.Therefore,they should not be modified casually.In this study,we present an optimizer that reduces the number of supporting structures by identifying the prime printing direction.Without rotation,models are projected in each direction in space,and the basis units involved in the generation of support structures are separated.Furthermore,the area of the supporting structures is calculated.Eventually,the prime printing direction with minimal supporting area is obtained through pattern-searching method.The results of the experiment demonstrated that the printing area was reduced by up to 60%for some cases,and the surface quality was also improved correspondingly.Furthermore,both the material consumption and fabrication time were decreased in most cases.In future work,additional factors will be considered,such as the height of the supporting S Xiao-Jun Chen xiaojunchen@sjtu.edu.cn 1 Institute of Biomedical Manufacturing and Life Quality Engineering,State Key Laboratory of Mechanical System and Vibration,School of Mechanical Engineering,Shanghai Jiao Tong University,Shanghai 200240,P.R.China 2 OMFS-IMPATH Research Group,Department of Imaging and Pathology,Faculty of Medicine,Katholieke Universiteit Leuven,Leuven,Belgium 3 Department of Oral and Maxillofacial Surgery,University Hospitals Leuven,Leuven,Belgium structures and the adhesion locations to improve the efficiency of this optimizer.

Automatic Segmentation Method for Cone-Beam Computed Tomography Image of the Bone Graft Region within Maxillary Sinus Based on the Atrous Spatial Pyramid Convolution Network

Sinus floor elevation with a lateral window approach requires bone graft(BG)to ensure sufficient bone mass,and it is necessary to measure and analyse the BG region for follow-up of postoperative patients.However,the BG region from cone-beam computed tomography(CBCT)images is connected to the margin of the maxillary sinus,and its boundary is blurred.Common segmentation methods are usually performed manually by experienced doctors,and are complicated by challenges such as low efficiency and low precision.In this study,an auto-segmentation approach was applied to the BG region within the maxillary sinus based on an atrous spatial pyramid convolution(ASPC)network.The ASPC module was adopted using residual connections to compose multiple atrous convolutions,which could extract more features on multiple scales.Subsequently,a segmentation network of the BG region with multiple ASPC modules was established,which effectively improved the segmentation performance.Although the training data were insufficient,our networks still achieved good auto-segmentation results,with a dice coefficient(Dice)of 87.13%,an Intersection over Union(Iou)of 78.01%,and a sensitivity of 95.02%.Compared with other methods,our method achieved a better segmentation effect,and effectively reduced the misjudgement of segmentation.Our method can thus be used to implement automatic segmentation of the BG region and improve doctors’work efficiency,which is of great importance for developing preliminary studies on the measurement of postoperative BG within the maxillary sinus.

人工肛门括约肌临床应用所面临的挑战（英文）

本文对目前临床使用的人工括约肌的安全性与有效性进行分析与讨论,对国内外目前正在开发的新装置和新方法进行比较,归纳出人工肛门括约肌在临床应用中遇到的关键问题是维持植入体与周围生物组织的远期力学相容性,该问题有望通过智能材料的利用得到解决。

A Novel Active Contour Model for Medical Image Segmentation

A novel segmentation method for medical image with intensity inhomogeneity is introduced.In the proposed active contour model,both region and gradient information are taken into consideration.The former,i.e.,region-based fitting energy,draws upon the region information and guarantees the accurate extraction of inhomogeneous image's local information.The latter,i.e.,an edge indicator,weights the length penalizing term to consider the gradient constrain.Moreover,signed distance penalizing term is also added to ensure accurate computation and avoid the time-consuming re-initialization of evolving level set function.Experiments for synthetic and real images demonstrate the feasibility and superiority of the proposed model.