Correlations between effective permeability and marrow contact channels surface of vertebral endplates

Jean-Michel Laffosse (1, 2) , Franck Accadbled (1, 2) , François Molinier (1) , Nicolas Bonnevialle (1, 2) , Jérôme Sales de Gauzy (1, 2) , Pascal Swider (3)

1 CHU Toulouse - Centre Hospitalier Universitaire de Toulouse
2 Laboratoire de biomécanique
3 IMFT - Institut de mécanique des fluides de Toulouse

Homeostasis of the intervertebral disc relies on nutrient supply and waste clearance through the dense capillary network that is in contact with the cartilage endplate (CEP). We developed a micro-computerized tomography (micro-CT) method to quantify the marrow contact channel surface (MCCS) with the CEP and to validate the hypothesis according to which MCCS was correlated to the effective permeability of the vertebral endplate (VEP) and influenced by the mechanical stimuli. The influence of compression loading on local vascularization was investigated. Six 4-week-old skeletally immature pigs were instrumented with left pedicle screws and rod at both T5-T6 and L1-L2 levels to create asymmetrical spine tethers. After 3 months of growth, three cylindrical specimens of the VEP (one central and two lateral right and left) were obtained from both the instrumented and the control levels. We used a previously validated method for measuring permeability. Micro-CT analysis (resolution 12 mu m) yielded a gray-scale 2D-image of the discal end of each specimen converted into a binary 2D-image to derive the MCCS. Correlations between MCCS and effective permeability were assessed. Effective permeability and MCCS were significantly decreased compared to the control group especially on the tethered side (-41..5%, p = 0.004 and -52.5%, p = 0.0009, respectively). Correlations were significant and showed maximal value (r(2) = 0.430, p < 0.0001) on the tethered side involving maximal compressive loadings. Mechanical stimuli, due to unbalanced growth, altered the vascularization and the convective properties of the CEP. The cascade of mechanobiological events should offer perspectives for research on disc degeneration and attempted treatment.

Mots clés: Micro-CT scan; Spine; Vertebral endplate; Permeability; Vascular network

Domaines: Biomécanique [physics.med-ph]

Jean-Michel Laffosse, Franck Accadbled, François Molinier, Nicolas Bonnevialle, Jérôme Sales de Gauzy, et al.. Correlations between effective permeability and marrow contact channels surface of vertebral endplates. Journal of Orthopaedic Research, 2010, 28 (9), pp.1229-1234. ⟨10.1002/jor.21137⟩. ⟨hal-01591232⟩