Grey scale ultrasonography and arthrography in evaluation of popliteal cysts.

Ultrasonography will reliably detect popliteal cysts of clinically significant size and improvements in ultrasound imaging have enhanced the value of ultrasound in relation to arthrography in the assessment of cyst rupture. Forty-eight knees in 25 patients suspected of having a popliteal cyst were examined by ultrasonography followed immediately by arthrography. Popliteal cysts were demonstrated in 40% (19/48) by ultrasound and in 46% (22/48) by arthrogram. Arthrography detected small cysts not seen with ultrasound, but altrasonic scanning showed cysts which did not fill on arthrography. A ruptured cyst or deep venous thrombosis was suspected in 10 patients. Rupture was confirmed in two patients by arthrography, in both of whom soft tissue changes and attenuation of the distal margin of the cysts were shown by ultrasound.