Abstract
An anatomically realistic three-dimensional (3D) finite element (FE) model of L4–L5 motion segment was created. The intact model was further modified to simulate two different disc degeneration grades, slight and moderate, at the L4–L5 segment. The implanted models were accordingly developed by incorporating a pair of 6mm diameter straight longitudinal rods position bilaterally into the degenerated models. In order to study the effect of implant stiffness on disc loading under compression, the stiffness of the longitudinal rod was varied between 1 and 83,000 N/mm in discrete steps. The intact, degenerated and implanted models were then exercised by applying 3,000N compressive force on the superior surface of L4 vertebra to investigate the load transmission characteristics of different implants. The results showed that the side effect of a degenerated disc is obvious for the lumbar segment load bearing capacity. The stiffness of the segment was increased due to the stiffer disc, which is caused by the severity of disc degeneration. The implant stiffness of lower than 2,000N/m has greater effect on disc loading and segment behavior. For an implanted model, the predicted annulus stress is close to the intact model when the implant stiffness is around 2000N/m. In addition, the effect of stiffness became less significant beyond this value. For dynamic stabilization purpose, the stiffness implant is suggested to be lower than 2000N/m
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References
Smith J, Sengupta, D. (2005) Dynamic stabilization device in the treatment of low back pain. Neurol India 53(4), 466–474.
Quint U, Wilke HJ, Loer F. et al (1998) Laminectomy and functional impairment of the lumbar spine: the importance of muscle forces in flexible and rigid instrumented stabilization-a biomechanical study in vitro. Eur Spine J 7:229–238.
Niosi CA, Zhu QA, Wilson DC. et al (2006) Biomechanical characterization of the three-dimensional kinematic behavior of the Dynesys dynamic stabilization system: an in vitro study. Eur Spine J 15:913–922.
Rohlmann A., Burra NK, Zander T. et al (2007) Comparison of the effects of bilateral posterior dynamic and rigid fixation devices on the loads in the lumbar spine: a finite element analysis. Eur Spine J Aug;16(8):1223–31.
Rohlmann A, Bergman G, Graichen F. et al (1997) Comparison of internal spinal fixation devices measured in vitro and in vivo. Med Eng Phys 19(6), 539–546.
Panjabi MM, White AA (1990) Clinical biomechanics of the spine. 2th ed. Lippincott-Raven.
Brinckmann P, Grootenboer H. (1991) Change of disc height, radial disc bulge, and intradiscal pressure from discectomy. Spine 16:641–6.
Goel VK, Kim YE, Lim TH et al (1988) An analytical investigation of the mechanics of spinal instrumentation. Spine 13:1003–1011.
Lavaste F, Skalli W, Robin S. et al (1992) Three-dimensional geometrical and mechanical modelling of the lumbar spine. J. Biomechanics 25(10):1153–1164.
Shirazi-Adl A, Shrivastava SC, Ahmed AM. (1984). Stress analysis of the lumbar disc-body unit in compression: a three-dimensional nonlinear finite element study. Spine 9(2), 120–134.
Kim YE, Goel VK, Weinstein JN et al (1991) Effect of disc degeneration at one level on the adjacent level in axial mode. Spine 16:331–335.
Iatridis JC, Setton LA, Weidenbaum M et al (1997) Alterations in the mechanical behavior of the human lumbar nucleus pulposus with degeneration and aging. J Orthop Res 15:318–22.
Kumaresan S, Yoganandan N, Pintar FA et al (2001) Contribution of disc degeneration to osteophyte formation in the cervical spine: a biomechanical investigation. J Orthop Res. 19(5):977–84.
Brown T, Hansen RJ, Yorra AJ. (1957) Some mechanical tests on the lumbosacral spine with particular reference to the intervertebral discs. J Bone Joint Surg 39-A(5), 1135–1164.
Markolf KL, Morris JM. (1974) The structural components of the intervertebral disc. J Bone Joint Surg 56-A(4), 675–687.
Virgin WJ (1951) Experimental invertigations into the physical properties of the intervertebral disc. J Bone Joint Surg 33B(4), 607–611.
McNally DS, Shackleford IM, Goodship AE et al (1996) In vivo stress measurement can predict pain on discography. Spine 21:2580–7.
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Zhang, Q.H., Teo, E.C. (2008). Effect of Dynamic Stabilization Device Stiffness on Disc Loading under Compression. In: Peng, Y., Weng, X. (eds) 7th Asian-Pacific Conference on Medical and Biological Engineering. IFMBE Proceedings, vol 19. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-79039-6_32
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DOI: https://doi.org/10.1007/978-3-540-79039-6_32
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