Characterizing the microstructural organization of collagenous fibrils in articular cartilage extracellular matrix using diffusion tensor imaging: A cross-sectional observational study

In the exploration of articular cartilage extracellular matrix (ECM) microstructural organization, the use of diffusion tensor imaging (DTI) has emerged as a promising noninvasive imaging technique. The study aimed to characterize the collagenous fibril architecture within the ECM of articular cartilage and to correlate these microstructural parameters with clinical symptoms in patients with varying degrees of knee pain. A cross-sectional study was conducted on a cohort of 472 patients who presented with knee pain. DTI metrics, including mean diffusivity (MD), fractional anisotropy (FA), axial diffusivity, and radial diffusivity, were acquired from the articular cartilage of the knee. Participants were stratified into groups based on age, sex, and the Kellgren-Lawrence grade to assess the severity of osteoarthritis. The study found sex differences in DTI metrics, with males having higher MD (P-value = .12) and lower FA (P-value: .01) than females. Age-related increases in MD (P-value = .04) and decreases in FA (P-value: = .02) indicated collagen degradation in ECM with age. Kellgren-Lawrence grade positively correlated with MD (P-value < .001) and negatively with FA (P-value = .02), confirming DTI metrics' link to cartilage pathology severity. No significant associations were found between DTI metrics and body mass index or smoking status. DTI was effective in evaluating the microstructure of collagen in cartilage ECM, indicating its metrics could be biomarkers for knee osteoarthritis severity. The results highlight DTI's role in noninvasively assessing cartilage health and detecting early ECM degeneration.