Quantitative Magnetic Resonance Imaging of Knee Articular Cartilage and Effusion-Synovitis: The Structural Response to Changes in Joint Loading
Abstract
Knee osteoarthritis (OA) is a progressive degenerative condition that can affect all tissues within the joint. Methods to measure early changes in joint structures and the effect of interventions are required. The purpose of this thesis was to investigate aspects of quantitative magnetic resonance imaging (MRI) as outcome measures in knee OA studies. Specifically, changes in articular cartilage composition and/or effusion-synovitis were examined in people with or at risk for knee OA and healthy controls, and after altering joint loads.
Chapter 2 is a systematic review that studied articular cartilage composition using MRI T2 and T1ρ relaxation in patients at risk for knee OA and healthy controls. We performed meta-analyses to examine the effect of knee OA risk factors on T2 and T1ρ relaxation. The presence of risk factors resulted in lengthened T2 and T1ρ relaxation. These findings support the use of compositional MRI to detect articular cartilage degeneration early in the OA disease process.
Chapter 3 explores the acute response of knee articular cartilage T2 relaxation to a functional loading stimulus in patients at risk for knee OA and healthy controls. T2 relaxation shortened similarly in both groups following the loading stimulus. The loading stimulus evoked consistent changes in articular cartilage composition but did not detect compromised articular cartilage in patients at risk for knee OA.
Chapter 4 evaluates the effect of high tibial osteotomy (HTO), a limb realignment surgery, on T2 relaxation of articular cartilage in patients with knee OA and varus alignment. Shortening of T2 relaxation was observed in the medial compartment, with no change in the lateral or patellar compartments, suggesting HTO can improve articular cartilage composition in the targeted compartment, without harming other compartments.
Chapter 5 studies the effect of knee load on effusion-synovitis, using HTO as a model. The change in knee adduction impulse was associated with the change in effusion-synovitis. The findings suggest that mechano-inflammation is an active pathway in knee OA that can respond to biomechanical intervention.
Overall, this thesis provides evidence that quantitative MRI is sensitive to structural changes of articular cartilage and effusion-synovitis at various stages of knee OA.