Finite element analysis on stress change of the lumbar disc degeneration / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the mechanical changes of the degenerated lumbar disc with finite element analysis.</p><p><b>METHODS</b>A three dimensional finite element model of a human lumbar spine at the L3-L4 disc was established by the software MIMICS and ABAQUS based on computer tomography images. Degeneration was modeled by changes in geometry and material properties. The model was loaded with 0.3 MPa in axial plane. The von Mises stress on the annulus fiber, nucleus pulposus, endplate and facet joints in healthy and degenerated discs was compared.</p><p><b>RESULT</b>Compared with healthy discs, the von Mises stress of disc distributed in the side of annulus fiber, the stress of nucleus pulposus decreased remarkably, the stress of endplate distributed in the posterior part, and the stress of facet joints increased for the degenerated disc.</p><p><b>CONCLUSION</b>The finite element models can provide a method of understanding the relationship between biomechanical performance of the disc due to disc degeneration.</p>

Dynamic observation of the biomechanic properties of sciatic nerve at the suture site in rats following repairing / 中华外科杂志

<p><b>OBJECTIVE</b>To observe the biomechanic properties of sciatic nerve at the suture site in rats following repairing.</p><p><b>METHODS</b>The right sciatic nerves of 40 white Sprague-Dawley 300-350 gm rats were exposed, cut and then repaired with 10-0 nylon sutures, laced in the epineurium. 0, 1, 3, 6 weeks after operation, the tensile strength of the sciatic nerves were measured, the data analyzed statistically.</p><p><b>RESULTS</b>The load-elongation curves for both the normal unoperated and operated nerves had the similar shape. The tensile strength of the 0 week was significant difference to 1, 3 and 6 weeks (P < 0.01). No significant difference was found among 1, 3 and 6 weeks.</p><p><b>CONCLUSION</b>The tensile strength of the injured nerves are recovered in the first week and resistant in 6 weeks after repairing.</p>