Figure 1

Progression of right proximal tibiofibular joint (TFJ) arthritis. (A) Coronal fat-saturated (FS) proton density MRI of the right knee shows bone marrow edema within the lateral aspect of the tibial plateau (arrowhead) and the fibular head (arrow). (B) Axial FS T2 sequence of the same joint demonstrating diffuse marrow edema of the fibular head and lateral tibial plateau. There is also adjacent soft tissue edema and a small amount of fluid within the proximal TFJ. (C) Follow-up coronal FS proton density sequence demonstrating an erosion at the site of prior bone marrow edema (arrows) as well as persistent inflammatory changes within the proximal TFJ (arrowhead). (D) Follow-up coronal FS T1 post gadolinium contrast-enhanced sequence again demonstrating the erosion seen in (C) (arrow) as well as enhancement of proximal TFJ synovium. (E) Reformatted coronal CT image of the same joint delineates the erosion at the lateral tibial plateau (arrow).