| The breakdown of articular cartilage, known as osteoarthritis (OA), is a disease that will affect everyone if they live long enough. This disease will significantly decrease the quality of life of patients through the lack of pain-free mobility of the affected joint. Currently, this disease cannot be diagnosed before painful symptoms present without invasive procedures. Once painful symptoms are present, the disease has progressed to a severe state where significant surgery is needed. A tool is needed that can non-invasively quantify articular cartilage structure and is sensitive to changes created by function and pathology.;My research begins by using polarized light (PL) imaging to quantify collagen fiber orientation in acellular collagen gels and bovine articular cartilage. This measurement tool, PL, is shown to be highly reproducible. PL is used to quantify variation in collagen fiber orientation in bovine patellar articular cartilage. The variation of collagen fiber orientation through the depth (perpendicular to the surface of the AC and parallel to the split line) of the articular cartilage is large, from zero to ninety degrees, and highly reproducible. The variation in the other two directions is small. These findings are used in the next study to improve our imaging sensitivity.;In the next study, magnetic resonance diffusion tensor imaging (DTI) is validated for quantifying collagen fiber orientation using polarized light (PL) imaging as the 'gold standard'. Collagen fiber orientation quantified by DTI is found not to be significantly different from the collagen orientation calculated by PL for acellular collagen gels and bovine articular cartilage. Determination of the thickness of specific cartilage zones made using DTI data is not statistically different than those made using PL data. My findings show that DTI gives unique and accurate three-dimensional data for the collagen fiber orientation in articular cartilage. This method is sensitive to mechanical loading and pathologic changes in articular cartilage; thus, it should provide a valuable imaging tool for noninvasively assessing cartilage diseases. |
