Small knee joint effusion. Avulsion fracture of the medial patellofemoral ligament/medial patellar retinaculum as it attaches onto the medial patella with mild marrow oedema. Hyperintensity within the adjacent Hoffa’s fat pad is noted. There is reciprocal marrow oedema within the lateral femoral condyle. Hyperintensity overlying the proximal medical collateral ligament, which is intact.