Bone & joints

Other nonneoplastic

Disc material

Last author update: 1 January 2013
Last staff update: 7 January 2022

Copyright: 2002-2023,, Inc.

PubMed Search: Disc material joints [title]

Vijay Shankar, M.D.
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Cite this page: Shankar V. Disc material. website. Accessed October 4th, 2023.
Definition / general
  • Normal intervertebral disc contains central nucleus pulposus (water, proteoglycans) within an annulus of obliquely oriented collagen fibers and a cartilaginous end plate
  • Elderly have shrunken, yellowed and dehydrated nucleus pulposus
  • Common surgical specimen, obtained after intervertebral disc prolapse or herniation, which is most common in ages 20 - 39 years
  • Anterior herniation usually is asymptomatic; posterior herniation puts pressure on nerve roots or spinal canal and produces symptoms
  • Posterior herniation present in 50% of older individuals at autopsy, usually in lumbar spine
  • Herniation refers to either prolapse, protrusion or extrusion

  • Protrusion:
    • Bulging of nucleus pulposus through weakened annulus fibrosus, usually posterior or posteriolateral
    • Can rarely disappear spontaneously

  • Prolapse:
    • Rupture of nucleus pulposus through annulus but not the posterior or anterior longitudinal ligament
    • Associated with neovascularization at edges of fibrocartilaginous fragments (Hum Pathol 1988;19:406)
    • Usually in lumbar region
    • May occur in thoracic or cervical disc

  • Extrusion: rupture of nucleus pulposus through annulus and posterior or anterior longitudinal ligament

  • Sequestration:
    • Fragmentation of extruded segment, may extend into spinal canal or far from site of rupture
    • Clinical symptoms depend on severity of herniation and position of offending disc
    • Patient may develop cauda equina syndrome in severe cases
Case reports
Microscopic (histologic) description
  • Annular fibrosus: collagen (pink)
  • Nucleus pulposus: pure cartilage (blue)
  • Herniated disk: vascular ingrowth
  • Also chondrocyte proliferation, structural alterations in form of tears and clefts, granular changes and mucous degeneration (BMC Res Notes 2011;4:497)
Microscopic (histologic) images

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Intervertebral disc

Disc degeneration

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