Quantifying collagen fibre architecture in articular cartilage using small-angle X-ray scattering

Collagen fibre architecture in articular cartilage is commonly described in terms of the predominant direction of fibre alignment. X-ray scattering has been used to study the distribution of fibre orientations in cartilage. In this paper, a new methodology for the analysis of small-angle X-ray scattering (SAXS) patterns of articular cartilage in order to quantitatively determine the distribution of collagen fibre orientations in the tissue is presented. A simple three-component model was used to fit intensity data from SAXS patterns to separate diffraction maxima from general diffuse scatter. Deconvolution of angular distributions of intensities of diffraction maxima obtained from SAXS patterns of articular cartilage and ligament samples yielded fibre orientation distributions in the cartilage samples. The methodology developed in this study worked reliably on a large set of SAXS patterns collected from native, dehydrated and trypsin-treated articular cartilage samples. The methods can be extended to quantitative analysis of small or wide angle X-ray scattering patterns obtained from other collagenous materials.