Validity of flounce sign to rule out medial meniscus tear in knee arthroscopy

The meniscal flounce is wavy fold in free inner border of meniscus seen during knee arthroscopy. The presence of this flounce in medial meniscus has been found to be highly predictive of normal medial meniscus. With meniscus related symptoms being commonest indication for undergoing knee arthroscopy, presence or absence of medial meniscus flounce, can be a good guiding sign. In this study, we aimed to validate the significance of the flounce sign in ruling out medial meniscus tear.

A prospective study was undertaken to validate the significance of flounce sign. There were 62 patients who underwent arthroscopic surgery of the knee over the duration of one and half years. Free inner margin of medial meniscus as seen through anterolateral portal was recorded for the presence or absence of flounce. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of this sign was then calculated for diagnosing normal medial meniscus. Significance was tested with chi square test with 95 % confidence interval.

A total of 62 cases were included. The sensitivity, specificity, PPV, NPV and accuracy of flounce sign was found to be 67.64 %, 92.85 %, 92 %, 70.27 % and 79.03 % respectively, and the result was significant (p value = 0.0001).

The flounce sign has been shown to have high diagnostic value. Use of it in routine knee arthroscopy can be helpful, particularly during screening procedure and in exploring tears which are usually not seen easily through routine portals.