Test yourself
Calf swelling: look behind the knee
5 questions. Pick an answer to see whether you are right and why. Your score appears at the end.
Question 1Where does a Baker's cyst arise?
Show answer
Answer c. A Baker's cyst is a distended gastrocnemius-semimembranosus bursa. It connects to the knee joint through a neck between these two structures, on the medial side of the popliteal fossa.
Question 2Which finding suggests a Baker's cyst has ruptured?
Show answer
Answer c. When the cyst leaks, fluid dissects down the calf, often between gastrocnemius and soleus. The cyst loses its smooth, rounded lower end.
Question 3You find a ruptured Baker's cyst in a patient with a swollen calf. What do you do next?
Show answer
Answer a. A Baker's cyst and a DVT can occur together, and a large cyst can compress the popliteal vein. The cyst does not replace the compression scan.
Question 4Why switch on colour Doppler over a round collection behind the knee?
Show answer
Answer d. A popliteal artery aneurysm can look like a cyst on greyscale. Flow inside the structure on colour Doppler changes the diagnosis and the referral.
Question 5A 65-year-old with knee osteoarthritis has a painful, swollen calf and bruising around the ankle. The veins compress normally. What is the most likely diagnosis?
Show answer
Answer a. Fluid tracking down from a ruptured cyst can cause calf swelling and bruising around the ankle, the crescent sign. Knee osteoarthritis is a common cause of a Baker's cyst. Normal compression makes proximal DVT unlikely.
Practise it with us
Four or five delegates per instructor, FAMUS-accredited faculty and long, supervised time on the probe.
Newsletter
A new pearl and test every month.
One email a month: a practical scanning skill, new Learn posts and course dates before they go public.