case_images: PMC7550959_01
case_images: (a) Radiograph shows preoperative anteroposterior (AP) view of the right knee. (b)
  Radiographs at 6 months after surgery show no findings of instability, loosening, or
  osteolysis (right: varus stress AP view, left: valgus stress AP view). (c) Radiograph at
  8 months after embolization shows Lipiodol in the superior lateral aspect (white
  arrow).
case_images: 10.1177_2050313X20964116-fig1.jpg
case_images: PMC7550959_01_10.1177_2050313X20964116-fig1.jpg
case_images: fig1-2050313X20964116
case_images: An 85-year-old woman was referred to our institution with right knee pain (Figure 1(a)). Radiographs showed no signs of instability, loosening, or osteolysis (Figure 1(b)). No recurrence was observed 8 months after embolization (Figure 1(c)).
case_images: (a) A contrast-enhanced computed tomography (CT) shows joint effusion and prominent
  synovial enhancement (white arrow), and suspected hyperemic synovium in superior lateral
  suprapatellar pouch. (b) A digital subtraction angiography shows hyperemic blush in the
  superior lateral aspect of the knee (black arrow). (c) Selective catheterization reveals
  abnormal hyperemic blush supplied from branches of the superior lateral genicular artery
  (white arrow).(d) After embolizing selectively with a suspension of
  N-butyl-2-cyanoacrylate (NBCA) and Lipiodol, subtotal devascularization of branches from
  superior lateral genicular artery is observed.
case_images: 10.1177_2050313X20964116-fig2.jpg
case_images: PMC7550959_01_10.1177_2050313X20964116-fig2.jpg
case_images: fig2-2050313X20964116
case_images: This showed joint effusion and prominent synovial enhancement in the superior lateral suprapatellar pouch (Figure 2(a)). Angiography revealed hyperemic blush in the superior lateral aspect of the knee (Figure 2(b)). Selective catheterization revealed a source of abnormal hyperemic blush supplied from branches of the superior lateral genicular artery (Figure 2(c)). After embolization, abnormal staining of the synovium was diminished (Figure 2(d)).