Sagittal Alignment With Downward Slope of the Lower Lumbar Motion Segment Influences Its Modes of Failure in Direct Compression: A Mechanical and Microstructural Investigation.

Study Design: Microstructural investigation of compression-induced herniation of ovine lumbar discs with and without added component of anterior-inferior slope.

Objective: Does increased shear arising from a simulated component of motion segment slope imitating sacral slope weaken the lateral annulus and increase risk of overt herniation at this same region.

Summary Of Background Data: An increase in sacral slope secondary to lordosis and pelvic incidence increases shear stresses at the lumbosacral junction and has been associated with an increase in spondylolisthetic disorders and back injury.

New evidence for structural integration across the cartilage-vertebral endplate junction and its relation to herniation.

Background Context: The cartilaginous and bony material that can be present in herniated tissue suggests that failure can involve both cartilaginous and vertebral-endplates. How structural integration is achieved across the junction between these two distinct tissue regions via its fibril and mineral components is clearly relevant to the modes of endplate failure that occur.

Purpose: To understand how structural integration is achieved across the cartilaginous-vertebral endplate junction.