Which spinal structure hypertrophy can contribute to acquired central canal stenosis?

• A. Interspinous ligament
• B. Ligamentum flavum
• C. Annulus fibrosus
• D. Facet joint capsule

Answer: (B)

When the spinal canal narrows due to aging and degenerative changes, thickening of the ligamentum flavum is a classic contributor to acquired central canal stenosis. This ligament runs along the back wall of the canal, and as it hypertrophies, it projects into the canal space and reduces the area available for the thecal sac and nerve roots. The effect is often more pronounced with spinal extension, when the flavum can buckle into the canal and worsen compression. While other structures like facet joints can also contribute to canal narrowing through arthropathy or osteophyte formation, the ligamentum flavum hypertrophy is the most typical and direct cause of acquired central canal stenosis.