Bakers Cyst

• Types of cysts

  • Baker’s cysts
  • Popliteal cysts
• Baker’s cyst

  A fluid-filled sac in the popliteal fossa, causing a lump
• Components of the popliteal fossa

  • Semimembranosus and semitendinosus tendons (superior and medial)
  • Biceps femoris tendon (superior and lateral)
  • Medial head of the gastrocnemius (inferior and medial)
  • Lateral head of the gastrocnemius (inferior and lateral)
• Pathophysiology of Baker’s cysts


  • In adults, usually secondary to degenerative changes in the knee joint
  • Associated with Meniscal tears, Osteoarthritis, Knee injuries, Inflammatory arthritis
  • Synovial fluid is squeezed out of the knee joint and collects in the popliteal fossa
  • Baker’s cysts are contained within the soft tissues and do not have their own epithelial lining
• Presentation of Baker’s cysts

  1. Patients may present with symptoms localised to the popliteal fossa: Pain or discomfort, Fullness, Pressure, A palpable lump or swelling, Restricted range of motion in the knee (with larger cysts)

  2. On examination, the lump will be most apparent when the patient stands with their knees fully extended. The lump will get smaller or disappear when the knee is flexed to 45 degrees (Foucher’s sign)

  3. Oedema may occur if the cyst compresses the
• Signs of Baker's Cyst

  • Lump most apparent when patient stands with knees fully extended
  • Lump gets smaller or disappears when knee is flexed to 45 degrees (Foucher’s sign)
  • Oedema may occur if the cyst compresses the venous drainage of the leg
  • Pain
  • Swelling
  • Erythema
• Ruptured Baker’s Cyst


  Causes inflammation in the surrounding tissues and calf muscle
• Ruptured Baker’s Cyst


  A critical differential diagnosis is deep vein thrombosis (DVT)
• Ruptured Baker’s Cyst

  Can rarely cause compartment syndrome
• Differential Diagnoses of a lump in the popliteal fossa

  • Deep vein thrombosis
  • Abscess
  • Popliteal artery aneurysm
  • Ganglion cyst
  • Lipoma
  • Varicose veins
  • Tumour
• Investigations for Baker's Cyst

  • Ultrasound
  • MRI
• Management of Baker's Cyst

  1. No treatment required for asymptomatic Baker’s cysts

  2. Non-surgical management includes modified activity, analgesia, physiotherapy, ultrasound-guided aspiration, steroid injections

  3. Surgical management typically involves arthroscopic procedures to treat underlying knee pathology contributing to the cyst, such as degenerative changes or meniscal tears
• Last updated

  August 2021