ABSTRACT
Three-dimensional finite element model of elbow was established to study the effect of medial collateral ligament (MCL) in maintaining the stability of elbow joint. In the present study a three-dimensional geometric model of elbow joint was established by reverse engineering method based on the computed tomography (CT) image of healthy human elbow. In the finite element pre-processing software, the ligament and articular cartilage were constructed according to the anatomical structure, and the materials and contacts properties were given to the model. In the neutral forearm rotation position and 0° flexion angle, by comparing the simulation data of the elbow joint with the experimental data, the validity of the model is verified. The stress value and stress distribution of medial collateral ligaments were calculated at the flexion angles of elbow position in 15°, 30°, 45°, 60°, 75°, 90°, 105°, 120°, 135°, respectively. The result shows that when the elbow joint loaded at different flexion angles, the anterior bundle has the largest stress, followed by the posterior bundle, transverse bundle has the least, and the stress value of transverse bundle is trending to 0. Therefore, the anterior bundle plays leading role in maintaining the stability of the elbow, the posterior bundle plays supplementary role, and the transverse bundle does little. Furthermore, the present study will provide theoretical basis for clinical recognizing and therapy of elbow instability caused by medial collateral ligament injury.
Subject(s)
Humans , Biomechanical Phenomena , Cadaver , Collateral Ligaments , Physiology , Elbow Joint , Physiology , Finite Element Analysis , Range of Motion, Articular , Tomography, X-Ray ComputedABSTRACT
Males typically have high rates of morbidity of primary bladder neck obstruction, while the existing urodynamic examination is invasive and more likely to cause false diagnosis. To build a non-invasive biomechanical detecting system for the male lower urinary tract, a finite element model for male lower urinary tract based on the collodion slice images of normal male lower urinary tract was constructed, and the fluid-structure interaction of the lower urinary tract was simulated based on the real urination environment. The finite element model of the lower urinary tract was validated by comparing the clinical experiment data with the simulation result. The stress, flow rate and deformation of the lower urinary tract were analyzed, and the results showed that the Von Mises stress and the wall shear stress at the membrane sphincter in the normal male lower urinary tract model reached a peak, and there was nearly 1 s delay than in the bladder pressure, which helped to validate the model. This paper lays a foundation for further research on the urodynamic response mechanism of the bladder pressure and flow rate of the lower urinary tract obstruction model, which can provide a theoretical basis for the research of non-invasive biomechanical detecting system.
ABSTRACT
OBJECTIVE:To optimize the formulation of Budesonide sustained-release tablet. METHODS:Using the cumula-tive releases in 2,4,8 h as investigation indexes,central composite design-response surface method was used to optimize the amount of hydroxypropylcellulose L(HPC-L),amount of soybean phosphatides,and filler(fixed total 200 mg)lactose- micro-crystalline cellulose mass ratio in the formulation of Budesonide sustained-release tablet,and the verification test was conducted. The release behaviors of prepared sustained-release tablet and original preparation in pH 7.2,7.0,6.8 phosphate buffer were com-pared. RESULTS:The optimal formulation was as follow as budesonide of 9 mg,HPC-L of 46.49 mg,soybean phosphatides of 9.23 mg,filler lactose-microcrystalline cellulose mass ratio of 1:2.9;the cumulative releases in 2,4,8 h were 21.9%,50.1%, 99.5%,the relative errors with predicted values (22.0%,50.0%,98.5%) were 0.45%,0.20%,1.02%(n=3),respectively. Compared with cumulative release of original preparation,the f2 was higher than 50. CONCLUSIONS:Budesonide sustained-re-lease tablet is successfully prepared,which shows similar release behavior to original preparations.