Nucleus pulposus herniation is the most common cause of sciatic pain and one of the most common indications for spine surgery worldwide. This condition presents as displacement of the nucleus pulposus into the annulus fibrosus or beyond the boundaries of the intervertebral disc. The disc anatomy consists of 2 main components, the nucleus pulposus and the annulus fibrosus.
The nucleus pulposus is composed of water, type II collagen, chondrocyte-like cells, and proteoglycans. This unique composition enables the nucleus pulposus to remain elastic and flexible under stress, allowing it to absorb compression. The annulus fibrosus is primarily composed of concentric layers of collagen type I fibers, forming a fibrous tissue with a helical distribution that surrounds the nucleus pulposus. The anterior annulus fibrosus is denser than the posterior annulus fibrosus and is attached to the vertebral body by Sharpey fibers.
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