Comparison of Dynamic Knee Contact Mechanics with T₂ Imaging in Different Ages of Healthy Participants

Aging is a known risk factor for Osteoarthritis (OA), however, relations between cartilage composition and aging remain largely unknown in understanding human OA. T₂ imaging provides an approach to assess cartilage composition. Whether these T₂ relaxation times in the joint contact region change with time during gait remain unexplored. The study purpose was to demonstrate a methodology for linking dynamic joint contact mechanics to cartilage composition as measured by T₂ relaxometry. T₂ relaxation times for unloaded cartilage were measured in a 3T General Electric magnetic resonance (MR) scanner in this preliminary study. High-speed biplanar video-radiography (HSBV) was captured for five 20-30-year-old and five 50-60-year-old participants with asymptomatic knees. By mapping the T₂ cartilages to the dynamic contact regions, T₂ values were averaged over the contact area at each measurement within the gait cycle. T₂ values demonstrated a functional relationship across the gait cycle. There were no statistically significant differences between 20- and 30-year-old and 50-60-year-old participant T₂ values at first force peak of the gait cycle in the medial femur (p = 1.00, U = 12) or in the medial tibia (p = 0.31, U = 7). In the medial and lateral femur in swing phase, the joint moved from a region of high T₂ values at 75% of gait to a minimum at 85-95% of swing. The lateral femur and tibia demonstrated similar patterns to the medial compartments but were less pronounced. This research advances understanding of the linkage between cartilage contact and cartilage composition. The change from a high T₂ value at ~ 75% of gait to a lower value near the initiation of terminal swing (90% gait) indicates that there are changes to T2 averages corresponding to changes in the contact region across the gait cycle. No differences were found between age groups for healthy participants. These preliminary findings provide interesting insights into the cartilage composition corresponding to dynamic cyclic motion and inform mechanisms of osteoarthritis.