Fig. 1

Preoperative magnetic resonance imaging showing a severe synovitis, resulting in degenerative–destructive arthropathy of the knee. T1 sequence in sagittal view showing villonodular synovitis at the posterior knee capsule (a). Short tau inversion recovery sequence in coronal projection showing edema and osteonecrosis of the two tibial hemiplates and the lateral femoral condyle (b). Axial T1 sequence showing signs of severe joint degeneration in the context of widespread villonodular synovitis (c, d)