Mapping the structural properties of the lumbosacral vertebral endplates

Grant, J. Pamela; Oxland, Thomas R.; Dvorak, Marcel F.

Affiliations

¹Division of Orthopaedic Engineering Research, University of British Columbia and Vancouver Hospital and Health Sciences Centre, Vancouver, British Columbia, Canada

²Division of Spine, Departments of Orthopaedics and Mechanical Engineering, University of British Columbia and Vancouver Hospital and Health Sciences Centre, Vancouver, British Columbia, Canada

Abstract and keywords

Study Design: A biomechanical investigation using indentation tests in a human cadaveric model to seek variation in the structural properties across the lower lumbar and sacral endplates.

Objectives: To determine 1) if there are regional differences in endplate strength and 2) whether any differences identified are affected by spinal level (lumbar spine vs. sacrum) or endplate (superior vs. inferior).

Summary of Background Data: It has been postulated that some regions of the vertebral body may be stronger than others. Conclusive data, either supporting or disproving this theory, would be valuable for both spine surgeons and implant designers because one mode of failure of interbody implants is subsidence into one or both adjacent vertebrae.

Methods: Indentation tests were performed at 27 standardized test sites in 62 bony endplates of intact human vertebrae (L3–S1) using a 3-mm-diameter, hemispherical indenter with a test rate of 0.2 mm/sec to a depth of 3 mm. The failure load and stiffness at each test site were determined using the load-displacement curves. Three-way analyses of variance were used to analyze the resulting data.

Results: Both the failure load and stiffness varied significantly across the endplate surfaces (P < 0.0001), with posterolateral regions being stronger and stiffer than the central regions. Characteristic distributions were identified in the lumbar superior, lumbar inferior, and sacral endplates. The failure load distributions were found to differ in 1) the superior lumbar and sacral endplates (P = 0.0077), 2) the inferior lumbar and sacral endplates (P = 0.0014), and 3) the superior and inferior lumbar endplates (P < 0.0001). The sacral and inferior lumbar endplates were both found to be stronger than the superior lumbar endplates (sacrum, P = 0.054; inferior, P = 0.008) but were not themselves significantly different (P = 0.89).

Conclusions: Highly significant regional strength and stiffness variations were identified in the lumbar and sacral endplates. The center of the bone, where implants are currently placed, is the weakest part of the lumbar endplates and is not the strongest region of the sacral endplate.

Keywords: compressive strength; indentation; endplate; stiffness; biomechanics; lumbar spine

Links

DOI: 10.1097/00007632-200104150-00012

PubMed: 11317111

WoS: 000168266200010

History

Received: 2000-05-04

Revised: 2000-09-18

Accepted: 2000-12-01

Cited Works (7)

Year	Entry
1969	Amstutz HC, Sissons HA. The structure of the vertebral spongiosa. J Bone Joint Surg. August 1969;51B(3):540-550.
1993	Flynn MJ, Cody DD. The assessment of vertebral bone macroarchitecture with x-ray computed tomography. Calcif Tiss Int. February 1993;53(suppl 1):S170-S175.
1966	Weaver JK. The microscopic hardness of bone. J Bone Joint Surg. March 1966;48A(2):273-288.
1960	Nachemson A. Lumbar intradiscal pressure: experimental studies on post-mortem material. Acta Orthop Scand. 1960;31(suppl 43):1-104.
1974	Behrens JC, Walker PS, Shoji H. Variations in strength and structure of cancellous bone at the knee. J Biomech. 1974;7(3):201-207.
1957	Perey O. Fracture of the vertebral end-plate in the lumbar spine: an experimental biomechanical investigation. Acta Orthop Scand. 1957;28(suppl 25):1-101.
1989	Keller TS, Hansson TH, Abram AC, Spengler DM, Panjabi MM. Regional variations in the compressive properties of lumbar vertebral trabeculae: effects of disc degeneration. Spine. September 1989;14(9):1012-1019.

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2007	Hulme PA, Boyd SK, Ferguson SJ. Regional variation in vertebral bone morphology and its contribution to vertebral fracture strength. Bone. December 2007;41(6):946-957.
2003	Ochia RS, Tencer AF, Ching RP. Effect of loading rate on endplate and vertebral body strength in human lumbar vertebrae. J Biomech. December 2003;36(12):1875-1881.
2010	Fields AJ, Lee GL, Keaveny TM. Mechanisms of initial endplate failure in the human vertebral body. J Biomech. 2010;43(16):3126-3131.
2020	Jin Y, Zhang T, Lui YF, Sze KY, Lu WW. The measured mechanical properties of osteoporotic trabecular bone decline with the increment of deformation volume during micro-indentation. J Mech Behav Biomed Mater. March 2020;103:103546.
2008	Chen H, Shoumura S, Emura S, Bunai Y. Regional variations of vertebral trabecular bone microstructure with age and gender. Osteoporos Int. October 2008;19(10):1473-1483.
2011	Au AG, Aiyangar AK, Anderson PA, Ploeg H-L. A new bone surrogate model for testing interbody device subsidence. Spine. July 15, 2011;36(16):1289-1296.
2010	Laffosse J-M, Kinkpe C, Gomez-Brouchet A, Accadbled F, Viguier E, Sales de Gauzy J, Swider P. Micro-computed tomography study of the subchondral bone of the vertebral endplates in a porcine model: correlations with histomorphometric parameters. Surg Radiol Anat. 2010;32(4):335-341.
2016	Fein P. Associations Between the Spatial Distribution of Bone Density in the Vertebra and Intervertebral Disc Health [Master's thesis]. Boston University; 2016.
2012	Kelly N. An Experimental and Computational Investigation of the Inelastic Behaviour of Trabecular Bone [PhD thesis]. Galway, Ireland: National University of Ireland Galway; September 2012.
2008	Mokhbi-Soukane D. Études numériques de la diffusion couplée d'oxygène, glucose et d'acide lactique dans le disque intervertébral [PhD thesis]. École polytechnique de Montréal; June 2008.
2008	Crookshank MCM. Optimizing Fracture Management: Correlating the Physical and Mechanical Properties of Bone to Computed Tomography to Generate an Estimate of Bone Quality [Master's thesis]. Queen's University; January 2008.
2005	Sran MM. Manual Therapy and the Osteoporotic Spine [PhD thesis]. Vancouver, BC: University of British Columbia; March 2005.
2010	Fields AJ. Trabecular Microarchitecture, Endplate Failure, and the Biomechanics of Human Vertebral Fractures [PhD thesis]. Berkeley, CA: Berkeley, University of California; 2010.
2018	Patel RR. Does Patient-Specific Implant Design Reduce Subsidence Risk in Lumbar Interbody Fusion? A Bottom Up Analysis of Methods to Reduce Vertebral Endplate Stress [PhD thesis]. University of Colorado Denver; 2018.
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2005	Guerin HAL. A Nonlinear Anisotropic Continuum Model of Human Annulus Fibrosus Mechanical Behavior [PhD thesis]. Philadelphia, PA: University of Pennsylvania; 2005.
2008	Parkinson RJ. Refining the Relationship Between the Mechanical Demands on the Spine and Injury Mechanisms Through Improved Estimates of Load Exposure and Tissue Tolerance [PhD thesis]. University of Waterloo; 2008.
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2011	Aiyangar AK. Physical and Computational Modeling of Subsidence of Anterior Interbody Fusion Devices [PhD thesis]. University of Wisconsin – Madison; 2011.