The researchers obtained x-rays and MRIs of the knees of patients at the start of the study and again 15 and 30 months later. At the start of the study, they looked to see which patients had bone marrow edema on MRI and who had malalignment of the leg bones. They then looked to see whose osteoarthritis had worsened on the follow-up x-rays. They explored whether patients with bone marrow edema, malalignment, or both were more likely to have worsened osteoarthritis than patients without these findings.