Regional variation in tensile properties and biochemical composition of the human lumbar anulus fibrosus.
METHODS
The structure-function relationship of anulus fibrosus of nondegenerate lumbar intervertebral discs was investigated.


OBJECTIVE
The tensile properties and biochemical composition of single lamella specimens from human anulus fibrosus and their variations with anatomic region were determined.


BACKGROUND
Regional differences in composition and ultrastructure suggest differences in tensile properties.


METHODS
Single lamella specimens were isolated from the anulus, equilibrated in 0.15 mol/L NaCl and tested in uniaxial tension using a slow strain-rate protocol. Adjacent specimens were used to determine biochemical composition (including hydration, collagen, proteoglycan, and hydroxypyridinium crosslink density). Tensile properties, biochemical composition, and anatomic location were compared.


RESULTS
Significant radial and circumferential variations in tensile properties of anulus were detected, with the anterior being stiffer than the posterolateral regions, and the outer being stiffer than the inner regions.


CONCLUSIONS
The regional differences in tensile properties may result predominantly from structural rather than compositional variations and may contribute to the clinical frequency of anulus failure in the posterolateral region.
Skaggs
D L
DL
Department of Orthopaedic Surgery, Columbia-Presbyterian Medical Center, New York, New York.
Weidenbaum
M
M
Iatridis
J C
JC
Ratcliffe
A
A
Mow
V C
VC
D003094:Collagen / Q000032:analysis; D003432:Cross-Linking Reagents / Q000032:analysis; D003627:Data Interpretation, Statistical; D005357:Fibrous Dysplasia of Bone / Q000209:etiology* / Q000378:metabolism; D006801:Humans; D007403:Intervertebral Disc / Q000737:chemistry / Q000473:pathology / Q000502:physiology*; D007437:Intrinsic Factor / Q000032:analysis; D008159:Lumbar Vertebrae / Q000378:metabolism / Q000473:pathology*; D011509:Proteoglycans / Q000032:analysis; D011725:Pyridines / Q000032:analysis; D013718:Tensile Strength / Q000187:drug effects
D003432:Cross-Linking Reagents; D011509:Proteoglycans; D011725:Pyridines; C014047:hydroxypyridines; D003094:Collagen; D007437:Intrinsic Factor