Baker’s Cyst

Baker’s cyst is a fluid-filled popliteal bursa located along the medial border of the popliteal fossa. It is an extension of the semimembranosus bursa posteriorly.

 

SYMPTOMS

• Symptoms associated with associated joint pathology (knee swelling or stiffness)
• Pain in the popliteal space
• Leg edema
• Prominence of the popliteal fossa
• Decreased range of motion of the knee
• Locking of the knee
• Foucher’s sign: the cyst becomes hard with knee extension and soft with knee flexion.
• Neuropathic lancinating pains radiating from the knee down the back of the leg
• Pain or discomfort with prolonged standing and hyperflexion of the knee
• Presence of associated DVT

CAUSES

_ Believed to be fluid distention of bursal sac separating semimembranous tendon from medial head of gastrocnemius.

_ In children, popliteal cysts are usually a primary process arising from the gastrocnemius-semimembranosus bursa without direct communication with the joint space.

_ In adults, Baker’s cysts are usually associated with pathologic changes of the knee joint, such as the following:

1. Rheumatoid arthritis (RA)
2. Osteoarthritis of the knee
3. Meniscal tears
4. Patellofemoral chondromalacia
5. Fracture
6. Gout
7. Pseudogout
8. Infection (tuberculosis)

DIAGNOSIS

Baker’s cyst frequently mimics DVT and is sometimes referred to as pseudothrombophlebitis syndrome.

IMAGING STUDIES

_ Plain radiographs (AP and lateral views)

_ Ultrasound

_ MRI

MANAGEMENT

• Rest
• Strenuous activity avoidance
• Knee immobilization sometimes necessary

_ NSAIDs can be used to treat underlying joint pathology (RA, gout, and pseudogout).

_ Arthrocentesis with intraarticular injection or injection of the cyst with corticosteroids (triamcinolone acetonide 40 mg).

_ Arthroscopic surgery to remove loose cartilaginous fragment

_ Partial or total meniscectomy

_ Open excision of the cyst