The endplate and trabecular bone in lumbar degenerative disc disease: A narrative review

To review the current knowledge surrounding degenerative disc disease focusing on the changes taking place in the end plate and trabecular bone. A narrative review of the current literature. An age-related reduction in blood supply to the disc contributes to tissue degradation. Degeneration, separate from this process, represents a disruption of the normal homeostasis. A process of vascular and sensory nerve in-growth in the annulus and localised areas of the end plate is associated with markers of inflammation and may represent a pain source. Treatment with local anti-inflammatories has, at best, mixed results. Bone mechanical indentation testing has been used to classify changes in ageing and degeneration demonstrating a location-dependant reduction in strength specific to each process. Modic changes include a process of inflammation, alteration of the mechanical and chemical environment and changes in bone turnover. The underlying cause for their development has multiple explanations including mechanical overload and microfracture, infection and inflammation in response to herniation of disc material through the end plate. We do know, however, that they seem to be at least partially reversible and not all are symptomatic. This reversibility potentially indicates an avenue of exploration for therapy. Restoring the complex balance of disc homeostasis may hold some promise and will rely on greater understanding of the pathological and material changes occurring at the disc-bone interface and their correlation with clinical imaging. Current treatment may be optimised with an understanding of the mechanical environment of the disc in patient subgroups.