Joint effusion with bone marrow oedema of low signal on T1 and high signal PD fat sat, involving the medial aspect of the patella and the lateral femoral condyle. Thickening with an abnormal intrinsic high signal of the medial patellar retinaculum and the medial patellofemoral ligament with periligamentous oedema. No associated chondral or osteochondral injury is seen. Vastus lateralis muscle strain with diffuse soft-tissue oedema.