Biomedical Engineering ; instrumentation ; Clothing ; Equipment Design ; Equipment and Supplies ; Monitoring, Ambulatory ; instrumentation

Wear of polyethylene (PE) tibial inserts is a significant cause of implant failure of total knee arthroplasty (TKA). PE inserts wear measurement and evaluation is the key in TKA researches. There are many methods to measure insert wear. Qualitative methods such as observation are used to determine the wear and its type. Quantitative methods such as gravimetric analysis, coordinate measuring machines (CMM) and micro-computed tomography (micro-CT) are used to measure the mass, volume and geometry of wear. In this paper, the principle, characteristics and research progress of main insert wear evaluation method were introduced and the problems and disadvantages were analyzed.
Arthroplasty, Replacement, Knee ; Humans ; Knee Prosthesis ; Polyethylene ; Prosthesis Design ; Prosthesis Failure ; Tibia ; Tomography, X-Ray Computed ; X-Ray Microtomography

BACKGROUND:Acute toxicity in vivo experiments in previous studies has been confirmed that the median lethal dose of chitosan microcapsules is higher than 2 000 mg/kg, but the specific pathogenic mechanism is unclear.
OBJECTIVE:To explore the influence of nano chitosan on MC3T3-E1 cellgrowth as a bone substitute material, as wel as the physiological function of rats.
METHODS:MC3T3-E1 cells were respectively cultured in Dulbecco’s modified Eagle’s medium with different concentrations of chitosan nanoparticles (0, 10 mg/L, 100 mg/L, 1 g/L, 10 g/L). The absorbance values were determined. Changes in MC3T3-E1 cellmorphology were observed by scanning electron microscope after 24 hours culture. 10 g/L nano chitosan suspension was prepared using PBS. Two different doses of nano chitosan suspension (166.67 and 16.67 mg/kg body weight) with PBS were injected intraperitoneal y into Sprague-Dawley rats, three times a week, for 4 weeks. The control group was injected with equal volume of physiologic saline. Serum biochemical markers were detected to analyze the functions of liver and kidney of rats. Moreover, histopathology slices were observed to evaluate the morphological changes of tissue and inflammatory infiltration.
RESULTS AND CONCLUSION:10 mg/L, 100 mg/L, 1 g/L, 10 g/L nano chitosan suspensions were found growth inhibition in MC3T3-E1 cells as compared with the control group (P<0.05). The reunion of chitosan was observed in the cytoplasm of MC3T3-E1 cells by transmission electron microscopy. On the cellsurface, pseudopodia formed, wavy undulating membrane, nucleus degeneration, fragmentation and condensation were found. Compared with the control group, blood urea nitrogen, Na+levels were significantly increased in rats injected with nano chitosan suspension at two dosages, but the K+level in the high concentration group was decreased significantly (P<0.05). cellapoptosis was found in the liver and renal tissue in a dose-dependent manner. It suggests that apoptosis may be the possible mechanism of nano chitosan toxicity, and normal physiological function may be impacted over a certain dose.

Objective Clutching internal fixtor(CIF)loose and the fixed part weakly heal up are often found in orthopedic clinic.In the present paper,biomechanics methods were used to try to explain and analyze these issues,providing a helpful suggestion for the application of CIF in clinic.Method Commerical finite element models(FEM)Program ANSYS was applied to set up the finite element models of orthopedic CIF and bone tissue to analyze and evaluate the biomechanical performances of the NiTi shape memory alloy CIF.Results There is an interaction force between embracing force of CIF and resistant force of bone tissue during the orthopedic clinical treatment.The embracing force along two semi-circular arms of CIF is increasing from the open position and reached the maximum value at the open symmetry position where the deformation of the bone occurred.Conclusion It is the key to choose the force loading position during the practical treatment,as the concentration force is the main force when there is an interactive force between the bone and the CIF.

Objective To study the force and pressure transmission through normal wrist,and the effect of transverse carpal ligament release on the biomechanics of carpal tunnel.Methods A 3-D finite element model of the wrist based on CT scan images was established.The load transmission of carpus and the distribution of contact stress on radiocarpal joint under axial compressive force on metacarpals as well as the effect of transverse carpal ligament(TCL)release on the displacement of carpal bones were computed and analyzed.Results The computational results of force and pressure transmission through normal carpus matched well with previous studies.The release of TCL resulted in radial and palmar displacement of the scaphoid,flexion and radial rotation of radiocarpal joint as well as a further radial deviation of the whole carpal tunnel.Conclusion A 3-D finite element model of the wrist that includes the carpal tunnel,distal radius and ulna and proximal metacarpals is developed.This model may simulate the load transmission better and contact stress distribution of carpal tunnel and radiocarpal joint,as well as provide an operational plateform for further deeply studing on biomechanical behavior of carpal structure.The computed and analyzed results of the effect of TCL release on the displacements of carpal bones can be served as related theoratic base on carpal tunnel syndrome,carpal tunnel release surgery and recovery after operation.

Objective:To investigate the effects on the new bone formation by different distraction rate during mandibular distraction osteogenesis in goats.Methods: The right side mandibles of twelve goats were distracted after corticortomy,and all the animals were divided into 3 groups randomly, the first group were distracted with 0.8 mm/day, the second group were distracted with 1.6 mm/day, the third group were distracted with 2.0 mm/day, and the left side mandible of 4 goats from above groups were selected randomly as the control group.Then the new generation bone after distraction with different rate were studied by bone density examination and three point bending test.Results: The bone density value of the 0.8 mm/day group were higher than the other two experimental groups; the results of three point bending test showed that the biomechanical strength of the new generation bone in 0.8 mm/day group was higher than the other two experimental groups.Conclusion:0.8 mm/day may be the best distraction rate in mandibular distraction osteogenesis.

Objective:To explore a scientific,complicated sampling method and corresponding formulas for sensitive question survey.Methods:Cochran W.G.'s classic sampling theories,two randomized response technique(RRT) models,total probability formulas,and properties of mean and variance were used in this study.Results:Formulas for the estimation of the population proportion and its variance for dichotomous sensitive questions on Greenberg model in cluster sampling and stratified cluster sampling were deduced.Formulas for the estimation of the population mean and its variance for quantitative sensitive question on the additive constant model in cluster sampling and stratified cluster sampling were deduced.Our survey methods and formulas were successfully applied in surveying the pre-marriage sex and cheating in examination in Soochow University.Conclusion:Our survey methods and formulas on two RRT models for sensitive question survey in cluster sampling and stratified cluster sampling have high reliablility.

By using three-dimensional finite element analysis method, the necessity of tail joints in the establishment of finite model specifically for the widely used tail-suspended rat experiments in weightlessness simulation was explored. A weightlessness tail-suspended three-dimensional finite element rat model was established using CT scan and Abaqus software, and the computation and analysis were conducted using the same model. The stress distribution and displacement in tail, lumbar spine, pelvis and femur of a tail-suspended rat both with and without cartilage were simulated and calculated.The results showed that stress distribution and displacement of tail-suspended rat were quite different between rats with cartilage and without cartilage, which affected the calculation precision of the model. Accordingly the consideration of articular cartilage in establishing the tail-suspended three-dimension finite element rat model is quite necessary,In addition, the asymmetry of pelvis stress distribution of tail-suspended rat suggests that the degree of balance of tail-suspended rat will affect the stress distribution in rats.

This paper is to report our study in which the differences between prosthetic restoration and surgical reconstruction using traditional clasp retention technology were analyzed based on three-dimensional finite element methods in our laboratory. Firstly, the maxillary unilateral defect model was developed using medical image processing software MIMICS. Secondly, the prosthesis was generated by mirroring technology. The clasp was designed according to the methods raised by Aramany. Then, the stress distribution of maxilla was calculated by simulating occlusion. According to the results, after osseointegration of surgical reconstruction, stresses of unaffected abutments were reduced significantly, and less stress of junction occurred near zygoma of affected side, which were all less than stresses of prosthesis restoration. Thus, removing the clasp of surgical reconstruction increased the stresses of unaffected abutments. The stress trends of maxillary components were different between prosthetic restoration and surgical reconstruction. Surgical reconstruction is better than prosthesis restoration in protection of the abutments. Clasp can alleviate the occlusal burden of maxilla. Varieties of retentive technologies can be considered in prosthesis restoration. The surgical reconstruction is more conducive to rehabilitate unilateral maxilla biomechanically in clinic.
Biomechanical Phenomena ; Finite Element Analysis ; Humans ; Image Processing, Computer-Assisted ; Mandibular Reconstruction ; methods ; Maxilla ; surgery ; Maxillofacial Prosthesis ; Osseointegration ; Zygoma

This paper proposed a mobile vital-signs monitoring system based on ZigBee localization and wireless transmission technology for the elderly in nursing home. The system can monitor the vital-signs (pulse, ECG and blood oxygen), localize human body and warn in emergency. The validity and accuracy of this system were testified by the experiments of mobile acquisition and storage of pulse. In these experiments, the measurement of pulse ranged from 50 to 170 time a minute, the mean error of which was less than 3%. The mean error of localizing was less than 4 m. And the data transmission rate was 250 kbps. The system, which effectively conducts the real-time monitoring of the health and safety situation for the elderly, has a great significance for protecting the elderly's life safety.
Aged ; Equipment Design ; Homes for the Aged ; Humans ; Monitoring, Physiologic ; instrumentation ; Nursing Homes