A protrusion is distinguished from a disc bulge in that it involves less than half the circumference of the disc. Conversely it is distinguished from a disc extrusion in that its base is wider than its 'dome' and it does not extend above or below the disc level.
Disc protrusions are further divided into:
- broadbased - base involves between 90 and 180 degrees of the circumference
- focal - base involves less than 90 degrees of the disc circumference
It may also be described in terms of its axial position, into central, subarticular, foraminal, extraforaminal or anterior.
Additionally the terms contained (outer annulus fibrosus laminae are intact) and non-contained (all laminae are deficient) are also sometimes used.
Synonyms & Alternative Spellings
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