The Aging Spine

Intervertebral disc degeneration is not confined to older populations; evidence shows that degenerative changes can be identified even in younger individuals, with prevalence rising progressively with advancing age. A growing body of literature has established a meaningful relationship between disc degeneration and the development of back pain. The etiology of disc degeneration is multifactorial, encompassing genetic predisposition alongside environmental and lifestyle influences. Structurally, the intervertebral disc is composed of three distinct components: the cartilage endplate, the annulus fibrosus, and the gelatinous nucleus pulposus. As one of the largest avascular structures in the human body, the disc relies almost entirely on diffusion across the endplate for its nutritional supply. Its cellular composition is relatively sparse, embedded within a rich extracellular matrix consisting predominantly of water, proteoglycans, collagens, and various noncollagenous proteins. Among the biochemical alterations accompanying degeneration, proteoglycan loss is the most clinically significant. Proteoglycans sustain disc hydration by generating osmotic pressure through their constituent glycosaminoglycan chains; their depletion reduces this osmotic capacity, impairing the disc’s ability to maintain adequate hydration under mechanical load. Magnetic resonance imaging (MRI) has become the gold standard for assessing disc degeneration in clinical practice, with the Pfirrmann grading system providing a standardized, reproducible framework for classifying degeneration severity on T2-weighted images. Modic changes, representing signal alterations in the vertebral endplate and adjacent bone marrow, are recognized as part of the degenerative process; notably, patients with Modic type 1 changes and chronic low back pain have shown a clinically meaningful response to antibiotic therapy in selected trials, raising questions about an infectious or inflammatory contribution in a subset of cases. Given the central role of inflammation in disc-related pain, proinflammatory cytokines have attracted considerable interest as potential molecular biomarkers reflecting pathological activity in disc degeneration. Emerging biological treatment strategies including intradiscal growth factor injection, cell-based therapies, and gene therapy represent promising avenues for modifying the degenerative process rather than simply managing its symptoms.