Annulus fibrosis


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Annulus fibrosis

The outer portion of the intervertebral disk made primarily of fibrocartilage rings.
Mentioned in: Herniated Disk
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Total ADC values of L1 intervertebral discs in Groups A (0.00154 [+ or -] 0.00008), B (0.00130 [+ or -] 0.00005), C (0.00122 [+ or -] 0.00007), and D (0.00107 [+ or -] 0.00007) significantly decreased with age ( P < 0.01); nucleus pulposus ADC values of L1 intervertebral discs in Groups A (0.00164 [+ or -] 0.00005), B (0.00156 [+ or -] 0.00007), C (0.00147 [+ or -] 0.00008), and D (0.00140 [+ or -] 0.00007) significantly decreased with age ( P < 0.01); annulus fibrosis ADC values of L1 intervertebral discs in Groups A (0.00129 [+ or -] 0.00014), B (0.00110 [+ or -] 0.00011), C (0.00095 [+ or -] 0.00009), and D (0.00082 [+ or -] 0.00012) significantly decreased with age ( P < 0.01).
In vitro and in vivo studies have suggested that aggrecan and Type II collagen serve important roles in the pathogenesis of IDD.[10],[11] Proteoglycan aggregates in adult human nucleus pulposus are mainly distributed within the extracellular matrix, while those of the annulus fibrosis are mainly distributed between collagen fibers.
The Pfirrmann grading system, closely related to signal strengths of nucleus pulposus and annulus fibrosis, is widely used in the clinical evaluation of IDD.[15] However, it is neither accurate nor particularly applicable for diagnosing early disc degeneration, in large part due to subjectivity of the examiner, weak classification effects on aged intervertebral discs, and insufficient capability for accurately assessing the degree of degeneration.
(8) They are not due to calcification of the anterior longitudinal ligament but rather ossification of the anterior portion of the annulus fibrosis of the intervertebral disc.
And they develop cracks or small tears in the outer layer, the annulus fibrosis, which can cause the inner layer, the nucleus pulposus, to be forced out, resulting in a bulging, herniated, or even ruptured disc.
The fusion that ankyloses the joints progresses vertically up the spine.[1,2,4,5,7] Initially, the apophyseal joints of the superior and inferior articular surfaces of the lumbar vertebrae are spared due to their constant motion.[2] But as the osteoblastosis progressively infiltrates the annulus fibrosis of each veretebral disk and ossifies it, as well as the surrounding soft-tissue attachments, the articulation of the apophyses is hindered and they, too, fuse.[1,2,4,7] The nucleus pulposis of the disk -- the liquid core surrounded by the annulus fibrosis -- may ossify or it may degenerate into a granulomatous pocket due to loss of vascularization from the surrounding osteoblastosis.
The IVD was composed of nucleus pulposus and annulus fibrosis which was modelled as hyperelastic using Mooney-Rivlin formulation [15, 16].
The Effects of Human Weight on Annulus Fibrosis. In general, the annulus stress increased as the human weight increased with the maximum annulus stress of 3.9 MPa for 1200 N load at L1-L2 lumbar segment as shown in Figure 7.
It was observed that increasing body weight will increase the pressure at nucleus pulposus and annulus fibrosis at all levels of the IVD.
We performed nucleoplasty in nine patients with a full-thickness tear in the annulus fibrosis, and at the last follow-up three of these patients (33.3%) were still satisfied with the procedure.