Fact-sheet: Popliteal cyst


Updated on 11/21/2021 at 6:01 PM

Note : 0/10
Share

View all RADEOS cases associated with this fact-sheet

Definition

Synovial cyst at the posterior aspect of the knee, communicating with the intra-articular space
= Baker's cyst

Clinical features

May be asymptomatic.
Posterior swelling relative to the knee.
Knee pain (related to osteoarthritis or an internal derangement).
Pseudo-phlebitis or cellulitis following rupture of the Baker's cyst

Ultrasound

Sufficient for the diagnosis of popliteal cyst and its complications

Check for the presence of the communicating channel located between the semimembranosus tendon and the muscle belly of the medial gastrocnemius.

Look for cyst rupture: fluid tracking superficially relative to the medial gastrocnemius

Particular topographic forms

  • Intramuscular form
  • Deep form

MRI

T1 hyposignal - T2 hypersignal
collection in the bursa between the semimembranosus and the medial gastrocnemius (most frequent case)

Rarely: in the supralateral bursa or in the popliteus muscle bursa

Differential diagnosis

Knee cysts:
- Meniscal cyst
- Tibiofibular cyst, arising from the proximal tibiofibular joint and communicating with the knee joint in 10% of cases
- Ganglion cyst of a cruciate ligament