Research ArticleArticles

Regional Variations in Shear Strength and Density of the Human Thoracic Vertebral Endplate and Trabecular Bone

Fred Xavier, Julio J. Jauregui, Nathan Cornish, Rebecca Jason-Rousseau, Dipal Chatterjee, Gavriel Feuer, Westley Hayes, Bhaveen H. Kapadia, John N. Carter, Hiroyuki Yoshihara and Subrata Saha
International Journal of Spine Surgery January 2017, 11 (1) 7; DOI: https://doi.org/10.14444/4007

Article Figures & Data

Figures

  • Fig. 1
    Fig. 1

    Cored cylindrical vertebral specimens before testing. Cancellous bone (A); Endplate with subchondral bone (C). Faxitron Xray of cancellous bone (B) and endplate with subchondral bone (D). Diameter: 7.24 mm; Height: 3.15 mm. Note the difference in porosity between endplate and cancellous bone.

  • Fig. 2
    Fig. 2

    Plain radiographs of thoracic vertebrae. A) Lateral view of a segment of the thoracic column. B) Axial view of a thoracic vertebra showing the different regions: anterior, central, and lateral. C) Lateral view: I- Endplate anterior superior (EP Ant Sup); II- Endplate central superior (EP Cen Sup); III- Cancellous anterior superior (Ant Sup); IVCancellous central superior (Cen Sup); V- Cancellous anterior middle (Ant Mid); VI- Cancellous central middle (Cen Mid); VII- Endplate anterior inferior (EP Ant Inf); VIII- Endplate central inferior (EP Cen Inf).

  • Fig. 3
    Fig. 3

    Stainless tube used for shear testing (left). Diagram showing the tube ending details (center). Diagram showing the apparatus for shear testing with the regulated saline bath at 37°C (right).

  • Fig. 4
    Fig. 4

    Load-displacement curves from shear testing of five specimens.

  • Fig. 5
    Fig. 5

    Mean (SE) density values for the three main regions of the cancellous bone. a) bulk density (g/cm3); b) optical density (g/cm2); c) material density (g/cm3); d) ash density (g/cm3). *: p < 0.05. Anterior (N = 10); Central (N = 26); Lateral (N = 27). Note that the anterior (ant) region had higher bulk and optical density values than the central (cen) and lateral (lat) regions. However, the anterior region had the lowest material and ash density values.

  • Fig. 6
    Fig. 6

    Mean (SE) cancellous bone elemental shear strength and maximum load to failure. Anterior (N = 10); Central (N = 26); Lateral (N = 27).

  • Fig. 7
    Fig. 7

    Mean (SE) density values for the three main regions of the vertebral endplate (EP). a) bulk density (g/cm3); b) optical density (g/ cm2); c) material density (g/cm3); d) ash density (g/cm3). *: p < 0.05. Anterior (N = 14); Central (N = 28); Lateral (N = 24). Note that the anterior (ant) region had higher bulk and optical density values than the central (cen) and lateral (lat) regions. However, the anterior region had the lowest material and ash density values.

  • Fig. 8
    Fig. 8

    Mean (SE) vertebral endplate (EP) elemental shear strength and maximum load to failure. Anterior (N = 14); Central (N = 28); Lateral (N = 24). *: p < 0.05. The anterior region was significantly weaker than the lateral region for elemental shear strength (p = 0.017) and maximum load to failure (p = 0.012).

Tables

  • Table 1

    Regional changes in vertebral mechanical properties.

    EndplateCancellous
    LateralCentral% DecreaseLateralCentral% Decrease
    Elem Shear M3.09 (0.71)2.11 (0.53)321.50 (0.37)1.56 (0.39)-4
    F1.98 (1.09)1.49 (0.75)250.80 (0.42)0.68 (0.29)14
    Glob Shear M1.91 (0.51)1.74 (0.48)90.87 (0.26)0.72 (0.22)18
    F1.62 (0.89)1.14 (0.55)300.46 (.024)0.34 (0.14)25
    Max Load M41.29 (10.43)28.22 (6.79)3213.87 (3.49)11.98 (3.03)14
    F24.28 (13.27)15.45 (6.93)367.88 (4.37)5.86 (2.83)26
    Endplate Cancellous
    Lateral Anterior % Decrease Lateral Anterior % Decrease
    Elem
    Shear     		M3.09 (0.71)0.44 (0.06)86 *1.50 (0.37)0.25 (0.08)83
    F1.98 (1.09)0.60 (0.14)700.80 (0.42)0.20 (0.02)75
    Glob
    Shear     		M1.91 (0.51)0.37 (0.07)810.87 (0.26)0.19 (0.08)78
    F1.62 (0.89)0.55 (0.07)660.46 (.024)0.16 (0.06)64
    Max Load M41.29 (10.43)5.14 (1.03)88 *13.87 (3.49)3.02 (1.07)78
    F24.28 (13.27)6.47 (2.02)737.88 (4.37)1.33 (0.39)83

    • Units of shear (elemental and global) strength and maximum load to failure are in MPa and N, respectively. Values represent the mean (SEM) of cancellous (median and superior combined) and endplate (inferior and superior combined). Changes are given as percentage of decrease from lateral to central and from lateral to anterior.

    • ↵* Statistical significance (*: p<0.05). M: male; F: female. Note the reduction in mechanical strength of 9% to 36% from lateral to central and of 66% to 88% from lateral to anterior (both endplates and cancellous bone).

  • Table 2

    Pearson correlation between mechanical strength, density, osteoarthritis level (K-L Score), and age.

    Vertebral Endplate
    K-L ScoreAgeDbulkDappDmatDoptDash
    Elem ShearM-.364*.108-.364*.440**.440**-.493**.337*
    F-.614**-.677**-.635**.739**.744**-.362.523**
    Glob ShearM-.427**.009-.300.507**.507**-.395*.393*
    F-.602**-.682**-.605**.713**.719**-.330.506**
    Max LoadM-.489**-.019-.260.419**.419**-.381*.321*
    F-.602**-.670**-.592**.717**.721**-.356.524**
    Vertebral Cancellous Bone
    K-L ScoreAgeDbulkDappDmatDoptDash
    Elem ShearM-.615**-.193-.059.368*.605**-.316.548**
    F-.837**-.679**-.471*.527**.811**-.546**.840**
    Glob ShearM-.367*-.005.003.460**.615**-.154.539**
    F-.837**-.678**-.439*.544**.787**-.465*.819**
    Max LoadM-.571**-.167-.069.437**.574**-.273.495**
    F-.825**-.690**-.464*.560**.815**-.506*.844**

    • Values represent r2. Negative sign (-) is for a negative correlation whereas an absence of sign stands for a positive one. M: male; F: female; K-L Score: Kelgren-Lawrence score; Dbulk: bulk density; Dapp: apparent density; Dmat: material density; Dopt: optical density; Dash: ash density.

    • ↵** Correlation is significant at 0.01 at the level (2-tailed).

    • ↵* Correlation is significant at 0.05 at the level (2-tailed).

  • Table 3

    Pearson correlation between density measurements, osteoarthritis level (K-L Score), and age.

    Vertebral Endplate
    AgeDbulkDappDmatDoptDash
    K-L ScoreM.627**.367*-.353*-.353*.338*-.039
    F.428*.680**-.510**-.504**.354-.355
    Age M1.189.073.073-.228.290
    F1.342-.525**-.570**-.136-.273
    Vertebral Cancellous Bone
    Age Dbulk Dapp Dmat Dopt Dash
    K-L Score M.686**.372*-.364*-.568**.260-.502**
    F.628**.463*-.513*-.746**.323-.763**
    Age M1.309-.168-.344*-.277-.311
    F1.186-.399-.843**-.059-.694**

    • Values represent r2. Negative sign (-) is for a negative correlation whereas an absence of sign stands for a positive one. M: male; F: female; K-L Score: Kelgren-Lawrence score; Dbulk: bulk density; Dapp: apparent density; Dmat: material density; Dopt: optical density; Dash: ash density.

    • ↵** Correlation is significant at 0.01 at the level (2-tailed).

    • ↵* Correlation is significant at 0.05 at the level (2-tailed).

Back to top

In this issue

Print
Download PDF
Article Alerts
Email Article
Citation Tools
Regional Variations in Shear Strength and Density of the Human Thoracic Vertebral Endplate and Trabecular Bone
Fred Xavier, Julio J. Jauregui, Nathan Cornish, Rebecca Jason-Rousseau, Dipal Chatterjee, Gavriel Feuer, Westley Hayes, Bhaveen H. Kapadia, John N. Carter, Hiroyuki Yoshihara, Subrata Saha
International Journal of Spine Surgery Jan 2017, 11 (1) 7; DOI: 10.14444/4007
Twitter logo Facebook logo Mendeley logo

Jump to section

Keywords