The vasculature in the outer annulus supplies only the periphery of the disc so that nutrition to the bulk of the disc, including all the inner annulus and nucleus pulposus, is derived from the vertebral epiphyseal end arteries where nutrients diffuse across the cartilaginous endplate to reach the disc. In this regard the vertebral endplate plays an important role in disc nutrition. Compromise of diffusion of nutrients to the disc cells may play a large part in the progression or even initiation of disc degeneration. Increasing evidence suggests that estrogen deficiency also influence the severity of disc degeneration in post-menopausal females. Structural disorganization of the vertebral endplate occurs with disc degeneration, with the most common endplate changes observed clinically being Schmorl's node. Schmorl's node is more commonly seen in post-menopausal women than younger women. Osteosclerosis, osteonecrosis and fibrosis associated with Schmorl's nodes can impede nutrient diffusion into the disc as well as removal of metabolites from the disc. We hypothesize that menopause negatively affects vertebral endplate quality and induces endplate degeneration. This endplate degeneration decreases nutrients diffusion from vertebral body into discs, and also impedes removal of metabolites, leads to further disc degeneration. To confirm our hypothesis, a cross-sectional post-contrast MRI study can be performed in pre-menopausal and post-menopausal women. If the hypothesis is confirmed, then low dose hormone replacement treatment may retard disc degeneration in post menopausal women and thereby limit the consequences associated with disc degeneration such as low back pain.
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