Sheep lumbar intervertebral discs as models for human discs

Objective. To determine the water Content, collagen content and collagen orientation angle in different regions of sheep lumbar discs.

Design. A laboratory study of sheep discs obtained from all abattoir.

Method. A total of 21 sheep lumbar discs were obtained from three lumbar spines. Water content was determined by oven drying (60 degreesC) to constant mass. Collagen content was determined by hydroxyproline analysis. Fibre orientation angles were determined by X-ray diffraction.

Results. Water content increased from 74% of total tissue Mass ill file Outer annulus, to 82% in the inner annulus, to 86% the nucleus. Collagen content decreased from 30% of total tissue mass in the Outer region to 20% in the inner region of the anterior and lateral annulus; it was 16% in the posterior annulus. The orientation angle of the collagen fibres decreased from 59degrees in the outer region to 56degrees in the inner region of the anterior and lateral annulus it was 51degrees in the Posterior annulus.

Conclusions. Sheep lumbar intervertebral discs provide a reasonable model for human lumbar intervertebral discs.