Pathophysiology and current understanding of degenerative disc disease

Table 3 Key structural, biomechanical, and biochemical consequences of degenerative disc disease

Entity	Primary changes	Main effects
Disc structure	Loss of height; dehydration; proteoglycan decline	Reduced hydrostatic pressure; impaired load absorption
Load redistribution	Increased loading of posterior elements	Facet joint degeneration; ligamentous strain
Spine stability	Segmental hypermobility; altered vertebral coupling	Mechanical instability; deformity (e.g., spondylolisthesis)
Spinal canal and foraminal anatomy	Ligamentum flavum hypertrophy; capsule thickening	Spinal/foraminal stenosis; nerve-root compression
Biochemical milieu	↑ Prostaglandins, nitric oxide, IL-1β, TNF-α	Nociceptor sensitization; chronic inflammation
Neural changes	Ingrowth of nociceptors + neovascularization	Discogenic pain; increased mechanical sensitivity
Overall outcome	Interaction of mechanical + inflammatory factors	Chronic pain, reduced mobility, progressive dysfunction

IL-1β: Interleukin 1beta; TNF-α: Tumor necrosis factor alpha.