Based on force sensing resistor(FSR) sensor, we designed insoles for pressure measurement, which were stable and reliable with a simple structure, and easy to wear and to do outdoor experiments with. So the insoles could be used for gait detection system. The hardware includes plantar pressure sensor array, signal conditioning unit and main circuit unit. The software has the function of data acquisition, signal processing, feature extraction and classification function. We collected 27 groups of gait data of a healthy person based on this system to analyze the data and study pressure distribution under various gait features, i.e. walking on the flat ground, uphill, downhill, up the stairs, and down the stairs. These five gait patterns for pattern recognition and classification by K-nearest neighbors (KNN) recognition algorithm reached up to 90% accuracy. This preliminarily verified the usefulness of the system.
Objective To study the biomechanical differences of the first carpometacarpal joint stability by using different reconstruction methods so as to provide theoretical basis for the clinical choice of reconstruction method. Methods The upper limb specimens were selected from 12 fresh adult cadavers, which had no fracture, bone disease, dislocation of wrist joint, deformity, degeneration, or ligament injury on the anteroposterior and lateral X-ray films. The specimens were randomly divided into 5 groups: normal group, injury group, palmar carpometacarpal ligaments reconstruction group, dorsal carpometacarpal ligaments reconstruction group, and palmar and dorsal carpometacarpal ligaments reconstruction group. Three normal specimens were used as normal group, and then were made of the first carpometacarpal joint dislocation models (injury group); after the first carpometacarpal joint dislocation was established in the other 9 specimens; the volar ligament, dorsal ligament, and volar-dorsal ligaments were reconstructed with Eaton-Little method, Yin Weitian method, and the above two methods in 3 construction groups. The biomechanical test was done to obtain the load-displacement curve and to calculate the elastic modulus. Results During biomechanical test, ligament rupture and loosening of Kirschner wire occurred in 1 case of injury group and palmar carpometacarpal ligaments reconstruction group; no slipping was observed. The elastic modulus values were (11.61±0.20), (5.39±0.12), (6.33±0.10), (7.12±0.08), and (8.30±0.10) MPa in normal group, injury group, palmar carpometacarpal ligaments reconstruction group, dorsal carpometacarpal ligaments reconstruction group, and palmar and dorsal carpometacarpal ligaments reconstruction group respectively, showing significant differences among groups (P<0.05). Conclusion Volar ligament reconstruction, dorsal ligament reconstruction, and volar-dorsal ligament reconstruction all can greatly improve the stability of the first carpometacarpal joint. And the effect of volar-dorsal ligament reconstruction is the best, but the stability can not restore to normal.
In the study of oral orthodontics, the dental tissue models play an important role in finite element analysis results. Currently, the commonly used alveolar bone models mainly have two kinds: the uniform and the non-uniform models. The material of the uniform model was defined with the whole alveolar bone, and each mesh element has a uniform mechanical property. While the material of the elements in non-uniform model was differently determined by the Hounsfield unit (HU) value of computed tomography (CT) images where the element was located. To investigate the effects of different alveolar bone models on the biomechanical responses of periodontal ligament (PDL), a clinical patient was chosen as the research object, his mandibular canine, PDL and two kinds of alveolar bone models were constructed, and intrusive force of 1 N and moment of 2 Nmm were exerted on the canine along its root direction, respectively, which were used to analyze the hydrostatic stress and the maximal logarithmic principal strain of PDL under different loads. Research results indicated that the mechanical responses of PDL had been affected by alveolar bone models, no matter the canine translation or rotation. Compared to the uniform model, if the alveolar bone was defined as the non-uniform model, the maximal stress and strain of PDL were decreased by 13.13% and 35.57%, respectively, when the canine translation along its root direction; while the maximal stress and strain of PDL were decreased by 19.55% and 35.64%, respectively, when the canine rotation along its root direction. The uniform alveolar bone model will induce orthodontists to choose a smaller orthodontic force. The non-uniform alveolar bone model can better reflect the differences of bone characteristics in the real alveolar bone, and more conducive to obtain accurate analysis results.
摘要:目的:研究生物降解聚DL乳酸(PDLLA)自锁式捆绑带固定骨折的生物力学性能。方法:80只新西兰大白兔随机分为两组,建立股骨干非负重骨折动物模型,应用生物降解自锁式捆绑带固定骨折为实验组,钢丝固定骨折为对照组,分别于术后1、4、8、12周行生物力学检查进行比较。结果:捆绑带组在术后4、8、12周均比钢丝组的弯曲强度高,但4周、12周时Pgt;005,无统计学差异,8周时Plt;005,提示有统计学差异。离体同种固定物不同时间段抗拉强度自身比较:钢丝固定术后4阶段抗拉强度比较Pgt;005,任何两两比较都没有统计学差异,抗拉强度未随术后时间延长发生明显下降。捆绑带固定术后4周与术后1周比较Pgt;005,抗拉强度无明显降低,但术后8周和术后12周时Plt;005,抗拉强度明显下降。结论:生物降解自锁式捆绑带在非负重骨折治疗中可发挥良好的固定作用。生物降解自锁式捆绑带降解时,应力传导促进了骨折的愈合。Abstract: Objective: To study the biomechanics function of selflocking cerclage band made of biodegradable material polyDLlactic acid (PDLLA) in the fixation of fractures. Methods: Eighty rabbits were divided into two groups. Femur fracture models were made. Fractures were fixed using biodegradable selflocking cerclage band in experimental group and metal fixation material in control group. The biomechanics was analyzed and compared after 1, 4, 8 and 12 weeks respectively． Results: The bending strength of experimental group is more ber than that of control group after 4, 8 and 12 weeks, but it was not statistically significant at 4 and 12 weeks (Pgt;005). It was statistically significant at 8 weeks (Plt;005). The tensile strength of the same cerclage instrument was compared at different stage in vitro, and the result of the control group was not statistically significant at the four stage (〖WTBX〗P〖WTBZ〗gt;005). Regarding the changes of tensile strength of the cerclage instrument at different stage, the result of the experimental group was not statistically significant after 1 and 4 weeks (Pgt;005). However, the decrease of tensile strength was statistically significant after 8 and 12 weeks (Plt;005). Conculsion: Biodegradable selflocking cerclage band could be used in thetreatment of nonweightbearing fractures. The stress force conducting promotes healing of fracture when the selflocking biodegradable cerclage band degrades.
Objective The biomechanical characteristics of three internal fixation modes for femoral subtrochanteric spiral fracture in osteoporotic patients were compared and analyzed by finite element technology, so as to provide the basis for the optimization of fixation methods for femoral subtrochanteric spiral fracture. MethodsTen female patients with osteoporosis and femoral subtrochanteric spiral fractures caused by trauma, aged 65-75 years old, with a height of 160-170 cm and a body weight mass of 60-70 kg, were selected as the study subjects. The femur was scanned by spiral CT and a three-dimensional model of the femur was established by digital technology. The computer aided design models of proximal intramedullary nail (PFN), proximal femoral locking plate (PFLP), and the combination of the two (PFLP+PFN) were constructed under the condition of subtrochanteric fracture. Then the same load of 500 N was applied to the femoral head, and the stress distribution of the internal fixators, the stress distribution of the femur, and the displacement of femur after fracture fixation were compared and analyzed under the three finite element internal fixation modes, so as to evaluate the fixation effect. ResultsIn the PFLP fixation mode, the stress of the plate was mainly concentrated in the main screw channel, the stresses of the different part of the plate were not equal, and gradually decreased from the head to the tail. In the PFN fixation mode, the stress was concentrated in the upper part of the lateral middle segment. In the PFLP+PFN fixation mode, the maximum stress appeared between the first and the second screws in the lower segment, and the maximum stress appeared in the lateral part of the middle segment of the PFN. The maximum stress of PFLP+PFN fixation mode was significantly higher than that of PFLP fixation mode, but significantly lower than that of PFN fixation mode (P<0.05). In PFLP and PFN fixation modes, the maximum stress of femur appeared in the medial and lateral cortical bone of the middle femur and the lower side of the lowest screw. In PFLP+PFN fixation mode, the stress of femur concentrated in the medial and lateral of the middle femur. There was no significant difference in the maximum stress of femur among the three finite element fixation modes (P>0.05). The maximum displacement occurred at the femoral head after three finite element fixation modes were used to fix subtrochanteric femoral fractures. The maximum displacement of femur in PFLP fixation mode was the largest, followed by PFN, and PFLP+PFN was the minimum, with significant differences (P<0.05). ConclusionUnder static loading conditions, the PFLP+PFN fixation mode produces the smallest maximum displacement when compared with the single PFN and PFLP fixation modes, but its maximum plate stress is greater than the single PFN and PFLP fixation mode, suggesting that the combination mode has higher stability, but the plate load is greater, and the possibility of fixation failure is higher.
Based on the application of finite element analysis in spine biomechanics, the research progress of finite element method applied in lumbar spine mechanics is reviewed and the prospect is forecasted. The related works, including lumbar ontology modeling, clinical application research, and occupational injury and protection, are summarized. The main research areas of finite element method are as follows: new accurate modeling process, the optimized simulation method, diversified clinical effect evaluation, and the clinical application of artificial lumbar disc. According to the recent research progress, the application prospects of finite element method, such as automation and individuation of modeling process, evaluation and analysis of new operation methods and simulation of mechanical damage and dynamic response, are discussed. The purpose of this paper is to provide the theoretical reference and practical guidance for the clinical lumbar problems by reviewing the application of finite element method in the field of the lumbar spine biomechanics.
This study aims to establish a multi-segment foot model which can be applied in dynamic gait simulation. The effectiveness and practicability of this model were verified afterwards by comparing simulation results with those of previous researches. Based on a novel hybrid dynamic gait simulator, bone models were imported into automatic dynamic analysis of mechanical systems (ADAMS). Then, they were combined with ligaments, fascia, muscle and plantar soft tissue that were developed in ADMAS. Multi-segment foot model was consisted of these parts. Experimental data of human gait along with muscle forces and tendon forces from literature were used to drive the model and perform gait simulation. Ground reaction forces and joints revolution angles obtained after simulation were compared with those of previous researches to validate this model. It showed that the model developed in this paper could be used in the dynamic gait simulation and would be able to be applied in the further research.
The stress distribution and different abduction angles have a close relation to the hip joint. The purpose of this study is to provide biomechanical evidence for the treatment or precaution of hip joint injuries. A three-dimensional model of the hip was established through a series of processing based on the normal human hip joint computed tomograph (CT) image data which were applied to reverse engineering software Mimics14.0 in this study. Firstly, a three-dimensional finite element model was generated with meshing and assigned material and then it was imported into the finite element analysis software Ansys13.0. At last the stress at the femoral neck was solved, computed and analyzed in the positive orthostatic position with 7 hip abduction angles of the hip joint: 0°, 5°, 10°, 15°, 20°, 25°, and 30°, respectively. The results showed that the stresses of femoral neck and outer region were obviously higher than those of front and rear area of the neck of femur in the upright position or abduction of a different angle. With the increase of abduction angle, femoral neck in front of the regional stress value basically unchanged and rear area decreased, but the more obvious changes occurred in the outer region although the stress of inner and outer area also increased gradually. The hip abduction may cause changes in stress distribution because of the femoral neck stress mostly concentrated in the inner and outer cortex, and therefore it has an important role in guiding for hip surgery injury patients to choose the most reasonable solutions and prevention initiatives.
This study aimed to evaluate the effect of sanguinarine on biomechanical properties of rat airway smooth muscle cells (rASMCs) including stiffness, traction force and cytoskeletal stress fiber organization. To do so, rASMCs cultured in vitro were treated with sanguinarine solution at different concentrations (0.005~5 μmol/L) for 12 h, 24 h, 36 h, and 48 h, respectively. Subsequently, the cells were tested for their viability, stiffness, traction force, migration and microfilament distribution by using methylthiazolyldiphenyl-tetrazolium bromide assay, optical magnetic twisting cytometry, Fourier transform traction microscopy, scratch wound healing method, and immunofluorescence microscopy, respectively. The results showed that at concentration below 0.5 μmol/L sanguinarine had no effect on cell viability, but caused dose and time dependent effect on cell biomechanics. Specifically, rASMCs treated with sanguinarine at 0.05 μmol/L and 0.5 μmol/L for 12 and 24 h exhibited significant reduction in stiffness, traction force and migration speed, together with disorganization of the cytoskeletal stress fibers. Considering the essential role of airway smooth muscle cells (ASMCs) biomechanics in the airway hyperresponsiveness (AHR) of asthma, these findings suggest that sanguinarine may ameliorate AHR via alteration of ASMCs biomechanical properties, thus providing a novel approach for asthma drug development.
The anterior cruciate ligament (ACL) reconstruction mostly relies on the experience of surgeons. To improve the effectiveness and adaptability of the tension after ACL reconstruction in knee joint rehabilitation, this paper establishes a lateral force measurement model with relaxation characteristics and designs an on-line stiffness measurement system of ACL. In this paper, we selected 20 sheep knee joints as experimental material for the knee joint stability test before the ACL reconstruction operation, which were divided into two groups for a comparative test of single-bundle ACL reconstruction through the anterolateral approach. The first group of surgeons carried out intraoperative detection with routine procedures. The second group used ACL on-line stiffness measurement system for intraoperative detection. After that, the above two groups were tested for postoperative stability. The study results show that the tension accuracy is (− 2.3 ± 0.04)%, and the displacement error is (1.5 ± 1.8)%. The forward stability, internal rotation stability, and external rotation stability of the two groups were better than those before operation (P < 0.05). But the data of the group using the system were closer to the preoperative knee joint measurement index, and there was no significant difference between them (P > 0.05). The system established in this paper is expected to help clinicians judge the ACL reconstruction tension in the operation process and effectively improve the surgical effect.