Date of Award


Document Type


Degree Name

Master of Science (MS)


Biomedical Engineering

First Advisor

Niccolo M. Fiorentino


Long-duration spaceflight will require developing technologies that meet the physiological demands of microgravity on the human musculoskeletal system. Articular cartilage of major weight-bearing joints such as the tibiofemoral (knee) joint is particularly at risk because its nutrition, metabolism, and overall function are dependent upon an optimal biomechanical and biochemical environment. Disruptions to cartilage homeostasis caused by joint unloading have been shown to induce an arthritic phenotype including cartilage thinning and altered matrix composition. Before joint degeneration countermeasures can be developed, we must gain a comprehensive understanding of how cartilage mechanics and composition are related in response to loading on Earth. Both knees of ten healthy participants were imaged with a 3T magnetic resonance imaging (MRI) scanner at two timepoints (7±3 days apart). T1rho and T2* MR images were acquired in two states: i) in a traditional setup without any load applied, and ii) while a custom loading device applied a 40% bodyweight load to the plantar aspect of the foot. Associations between mechanical metrics (cartilage deformation, cartilage strain, change in bone-bone distance, and change in cartilage contact area) and compositional metrics (T1rho and T2* relaxation times) were identified. Significant decreases in bone-bone distance were seen in all tibiofemoral compartments in response to load. Articular cartilage thickness consistently decreased, but not significantly in every compartment. Compressive strains ranged from 0-5.4%. There were no significant changes in cartilage contact area. T1rho and T2* relaxation times changed significantly with the application of load, with the femoral and tibial cartilage exhibiting opposite responses. There were no significant associations between mechanical and compositional metrics for T1rho scans. T2* scans had four significant relationships: unloaded composition and change in bone-bone distance in the lateral femur; change in composition and change in bone-bone distance in the lateral femur; change in composition and change in contact area in the lateral femur; and change in composition and change in bone-bone distance in the medial tibia. Results from this work demonstrate that loading can induce tibiofemoral articular cartilage composition changes even with small changes in mechanics.



Number of Pages

57 p.

Available for download on Tuesday, April 15, 2025