Diagnosis of popliteal cyst: double-contrast arthrography and sonography.

One hundred consecutive patients who had trauma to the knee were examined by sonography and double-contrast arthrography to evaluate the presence or absence of popliteal cyst. In 58 cases both tests were negative, while in 15 both were positive. Each of those 15 patients had pain and/or a palpable mass behind the knee. In 27 remaining patients the arthrogram demonstrated a popliteal cyst that was not detected on the sonogram. None of the 27 patients complained of pain in the popliteal fossa or had a palpable mass in the area. The sonographic findings, however, showed good correlation with these clinical symptoms. This paper attempts to analyze these discrepancies and to evaluate the advantages and disadvantages of each method.