IJCM  Vol.4 No.7 A , July 2013
The Endplate Morphology Changes with Change in Biomechanical Environment Following Discectomy
ABSTRACT
Bone is a dynamic structure and is known to respond to changes in the load over time, in accordance with Wolff’s law. It states that the bone changes its shape and internal architecture in response to stresses acting on it [1]. Therefore, any structural changes in the spine may lead to bone remodeling due to changes in the optimal stress pattern. The changes in apparent density and thickness of the endplates following discectomy of varying amounts were analyzed. The study design coupled a bone remodeling algorithm based on strain energy density theory of adaptive remodeling with an experimentally validated 3D ligamentous finite element model of the spine. The apparent density and thickness of the index level endplates decreased above and below the region of discectomy. On the other hand, these parameters showed increases at the remaining regions of the endplate. There were no correlations between the amount of nucleus removed and the average percentage changes in apparent density and thickness of endplate above and below the discectomy region. However, the average percentage changes in apparent density and thickness at endplate in the other region increased with increase in amount of nucleus removed. These predictions are in agreement with the clinical observations [2-6].

Cite this paper
A. Agarwal, A. Agarwal and V. Goel, "The Endplate Morphology Changes with Change in Biomechanical Environment Following Discectomy," International Journal of Clinical Medicine, Vol. 4 No. 7, 2013, pp. 8-17. doi: 10.4236/ijcm.2013.47A1002.
References
[1]   J. Wolf, “Julis Wolff and His Law of Bone Remodeling,” Der Orthopade, Vol. 24, No. 5, 1995, p. 378.

[2]   T. Malinin and M. D. Brown, “Changes in Vertebral Bodies Adjacent to Acutely Narrowed Intervertebral Discs: Observations in Baboons,” Spine (Phila Pa 1976), Vol. 32, No. 21, 2007, pp. E603-E607.

[3]   T. Yasuma, et al., “Histological Changes in Aging Lumbar Intervertebral Discs. Their Role in Protrusions and Prolapses,” The Journal of Bone and Joint Surgery, Vol. 72, No. 2, 1990, pp. 220-229.

[4]   D. Resnick and G. Niwayama, “Intravertebral Disk Herniations: Cartilaginous (Schmorl’s) Nodes,” Radiology, Vol. 126, No. 1, 1978, pp. 57-65.

[5]   R. J. Moore, et al., “Remodeling of Vertebral Bone after Outer Anular Injury in Sheep,” Spine (Phila Pa 1976), Vol. 21, No. 8, 1996, pp. 936-940. doi:10.1097/00007632-199604150-00006

[6]   S. Roberts, et al., “Does the Thickness of the Vertebral Subchondral Bone Reflect the Composition of the Intervertebral Disc?” European Spine Journal, Vol. 6, No. 6, 1997, pp. 385-389. doi:10.1007/BF01834064

[7]   W. T. Edwards, et al., “Structural Features and Thickness of the Vertebral Cortex in the Thoracolumbar Spine,” Spine, Vol. 26, No. 2, 2001, pp. 218-225. doi:10.1097/00007632-200101150-00019

[8]   S. Ferguson and T. Steffen, “Biomechanics of the Aging Spine,” European Spine Journal, Vol. 12, 2003, pp. 97103. doi:10.1007/s00586-003-0621-0

[9]   J. P. Grant, T. R. Oxland and M. F. Dvorak, “Mapping the Structural Properties of the Lumbosacral Vertebral Endplates,” Spine, Vol. 26, No. 8, 2001, pp. 889-896. doi:10.1097/00007632-200104150-00012

[10]   T. G. Lowe, et al., “A Biomechanical Study of Regional Endplate Strength and Cage Morphology as It Relates to Structural Interbody Support,” Spine, Vol. 29, No. 21, 2004, pp. 2389-2394. doi:10.1097/00007632-200104150-00012

[11]   V. K. Goel, et al., “Cancellous Bone Young’s Modulus Variation within the Vertebral Body of a Ligamentous Lumbar Spine—Application of Bone Adaptive Remodeling Concepts,” Journal of Biomechanical Engineering, Vol. 117, No. 3, 1995, pp. 266-271. doi:10.1115/1.2794180

[12]   N. M. Grosland and V. K. Goel, “Vertebral Endplate Morphology Follows Bone Remodeling Principles,” Spine (Phila Pa 1976), Vol. 32, No. 23, 2007, pp. E667E673.

[13]   J. Homminga, et al., “Can Vertebral Density Changes Be Explained by Intervertebral Disc Degeneration?” Medical Engineering & Physics, Vol. 34, No. 4, 2012, pp. 453458. doi:10.1016/j.medengphy.2011.08.003

[14]   J. D. Jovanovic and M. L. Jovanovic, “Biomechanical Model of Vertebra Based on Bone Remodeling,” Medicine and Biology, Vol. 11, No. 1, 2004, pp. 35-39.

[15]   F. M. Pfeiffer, D. L. Abernathie and D. E. Smith, “A Computational Approach to Bone Remodeling Postoperative to Facet Fusion,” ASME 2008 3rd Frontiers in Biomedical Devices Conference, Irvine, 18-20 June 2008, pp. 13, 14.

[16]   S. Vadapalli, et al., “Biomechanical Rationale for Using Polyetheretherketone (PEEK) Spacers for Lumbar Interbody Fusion—A Finite Element Study,” Spine (Phila Pa 1976), Vol. 31, No. 26, 2006, pp. E992-E998.

[17]   A. P. Dooris, et al., “Load-Sharing between Anterior and Posterior Elements in a Lumbar Motion Segment Implanted with an Artificial Disc,” Spine (Phila Pa 1976), Vol. 26, No. 6, 2001, pp. E122-E129.

[18]   V. K. Goel, et al., “Anatomic Facet Replacement System (AFRS) Restoration of Lumbar Segment Mechanics to Intact: A Finite Element Study and in Vitro Cadaver Investigation,” SAS Journal, Vol. 1, No. 1, 2007, pp. 46-54. doi:10.1016/S1935-9810(07)70046-4

[19]   V. K. Goel, et al., “Interlaminar Shear Stresses and Laminae Separation in a Disc. Finite Element Analysis of the L3-L4 Motion Segment Subjected to Axial Compressive Loads,” Spine (Phila Pa 1976), Vol. 20, No. 6, 1995, pp. 689-698. doi:10.1097/00007632-199503150-00010

[20]   K. Sairyo, et al., “Athletes with Unilateral Spondylolysis Are at Risk of Stress Fracture at the Contralateral Pedicle and Pars Interarticularis—A Clinical and Biomechanical Study,” American Journal of Sports Medicine, Vol. 33, No. 4, 2005, pp. 583-590. doi:10.1177/0363546504269035

[21]   H. Weinans, et al., “Adaptive Bone Remodeling around Bonded Noncemented Total Hip Arthroplasty: A Comparison between Animal Experiments and Computer Simulation,” Journal of Orthopaedic Research, Vol. 11, No. 4, 2005, pp. 500-513. doi:10.1002/jor.1100110405

[22]   D. R. Carter, “Mechanical Loading Histories and Cortical Bone Remodeling,” Calcified Tissue International, Vol. 36, No. 1, 1984, pp. S19-S24. doi:10.1007/BF02406129

[23]   W. T. Edwards, et al., “Structural Features and Thickness of the Vertebral Cortex in the Thoracolumbar Spine,” Spine (Phila Pa 1976), Vol. 26, No. 2, 2001, pp. 218-225.

[24]   H. Weinans, R. Huiskes and H. Grootenboer, “The Behavior of Adaptive Bone-Remodeling Simulation Models,” Journal of Biomechanics, Vol. 25, No. 12, 1992, pp. 1425-1441. doi:10.1016/0021-9290(92)90056-7

[25]   D. R. Carter and W. C. Hayes, “The Compressive Behavior of Bone as a Two-Phase Porous Structure,” The Journal of Bone and Joint Surgery, Vol. 59, No. 7, 1977, pp. 954-962.

[26]   V. K. Goel, et al., “Cancellous Bone Young’s Modulus Variation within the Vertebral Body of a Ligamentous Lumbar Spine—Application of Bone Adaptive Remodeling Concepts,” Journal of Biomechanical Engineering, Vol. 117, No. 3, 1995, pp. 266-271. doi:10.1115/1.2794180

[27]   M. J. McGirt, et al., “A Prospective Cohort Study of Close Interval Computed Tomography and Magnetic Resonance Imaging after Primary Lumbar Discectomy: Factors Associated with Recurrent Disc Herniation and Disc Height Loss,” Spine, Vol. 34, No. 19, 2009, pp. 20962103. doi:10.1097/BRS.0b013e3181b34a9a

[28]   K. N. Fountas, et al., “Correlation of the Amount of Disc Removed in a Lumbar Microdiscectomy with Long-Term Outcome,” Spine, Vol. 29, No. 22, 2004, pp. 2521-2524. doi:10.1097/01.brs.0000145413.79277.d0

[29]   G. Schmid, et al., “Lumbar Disk Herniation: Correlation of Histologic Findings with Marrow Signal Intensity Changes in Vertebral Endplates at MR Imaging1,” Radiology, Vol. 231, No. 2, 2004, pp. 352-358. doi:10.1148/radiol.2312021708

[30]   F.-D. Zhao, et al., “Vertebral Fractures Usually Affect the Cranial Endplate Because It Is Thinner and Supported by Less-Dense Trabecular Bone,” Bone, Vol. 44, No. 2, 2009, pp. 372-379. doi:10.1016/j.bone.2008.10.048

[31]   A. G. Patwardhan, et al., “Effect of Compressive Follower Preload on the Flexion-Extension Response of the Human Lumbar Spine,” Journal of Orthopaedic Research, Vol. 21, No. 3, 2006, pp. 540-546. doi:10.1016/S0736-0266(02)00202-4

 
 
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