The Design Of Loading Device For Disc Tissue Engineering And Finite Element Modeling And Analysis

Low back pain and other spinal diseases caused by intervertebral disc degradation ordefects have affected human livelihood and economy seriously. Although a lot of newtechnologies and methods are be used in clinic treatment, they can not solve the basic problem.In recent years, the new technologies related with tissue engineering improving continuouslybring the hope for the complete regeneration of the morphology and physiological function ofthe degradated intervertebral disc.From the perspective of intervertebral disc biomechanics, this project developed a dual-frequency compression- torsional loading device for Tissue Engineering of intervertebral disc,according to the movement and the loaded form of the disc. The device provides axial dualfrequency compression and torsion load, the dual frequency compression contains twosystems which are low-frequency high-amplitude and high-frequency low-amplitude. And thelow-frequency high-amplitude loading is achieved by motor driven cam, adjusting the motorspeed to achieve the different loading frequencies; high-frequency load by the usage ofpiezoelectric ceramics. Torsion system uses stepper motor to drive the stage rotation, and theangle is controled by adjusting the rotation step angle. The device makes the intervertebraldisc subjected to the axial compression load and torsional stress, which is similar to the realenvironment in vivo. And it may be helpful to cultivate the artificial disc tissue matched withthe structure-function of living one, and also provides favorable conditions for furtherresearch of the intervertebral disc biomechanics.In addition, it makes use of the three-dimensional medical image processing softwareMimics and reverse engineering software Gemagic, constructs the L3-L4 lumbar section of ahealthy 52 years old men. With Ansys software it builds the complete disc model, includingcartilage board, fiber, matrix, medullary nuclear, and all of composition are given reasonableunit types and material properties. The disc assembly model is analyzed in terms of staticsconditions, imitated positive pressure, flexion, lateral bending, torsion and other complexmovements , the stress value and displacement change separately of the disc were calculatedunder relevant loads, respectively. The results of finite element analysis, under the effect ofpressure, fiber ring expand to forward, and the biggest tensile stress is in the front of the fiber.While in flexion and lateral bending, the stress mainly concentrated in the rear, the maximumvalue occurs in small joint spinous. The main stress appears in back of the intervertebral discin torsion loaded, the stress reduces from outer to inner step by step, and the value of fiberstress is bigger in the front of the modle. The conclusion may provide the theoretical basis foranalysis pathogenesis mechanism, improvement of the procedures and could reduce theprobability of recurrent.