100 patients with a clinical diagnosis of knee osteoarthritis and symptomatic pain on walking were included in this study to assess the effect of corticosteroid injections on synovitis and how this may mediate pain reduction. Patients were randomized to undergo either a single methylprednisolone or saline injection. As part of the treatment, all patients participated in an individualized exercise therapy program under the supervision of a physiotherapist. The main outcomes of interest of the current study were volume and degree of perfusion on dynamic contrast-enhanced MRI and patient-reported outcome measures using the KOOS. The results of this study indicated that administration of a single intra-articular glucocorticoid did not demonstrate a significantly greater effect, compared to saline injection, on synovitis assessed on DCE-MRI, as well as synovitis and effusion on static CE MRI. Additionally, the patient-reported outcomes did not significantly differ between groups and no statistically significant MRI-explanatory variables were identified were observed at 14 weeks.