Radiographic investigation of popliteal cysts.

Forty-one patients with popliteal cysts were examined radiographically. All cysts consisted of a dilated gastrocnemio-semimembranosus bursa. A valve mechanism at the site of their communication with the joint was demonstrated by a specific radiographic technique in the majority of cases. The radiographic findings in popliteal cyst ruptures simulating deep venous thrombosis are described.