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

Abstract

BackgroundThe 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.MethodsA 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.ResultsA 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).ConclusionThe 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.

The significance of the meniscal flounce sign in canine stifle arthroscopy

“…When the meniscal flounce sign was absent, a meniscal tear was found in 92.7% of cases. The overall accuracy of the meniscal flounce as a sign that could be used to identify the meniscal tear status was 94.6%, which is similar to the findings in human knee arthroscopy 12–14 …”

“…Our sample size was large enough to obtain significant data regarding the meniscal flounce sign but the total number of stifles with meniscal tears was small. This could have resulted in the lower specificity in our study compared with human surgical studies 13,14 . A larger sample size could alter the statistical power of this study.…”

“…The overall accuracy of the meniscal flounce as a sign that could be used to identify the meniscal tear status was 94.6%, which is similar to the findings in human knee arthroscopy. [12][13][14] The absence of the meniscal flounce sign was noted in menisci with all tear types except for radial tears. These results indicate that the loss of the meniscal flounce sign is most consistent with a longitudinal, bucket handle, or complex/degenerative tear of the medial meniscus.…”

“…This could have resulted in the lower specificity in our study compared with human surgical studies. 13,14 A larger sample size could alter the statistical power of this study. Additional true negatives would increase the specificity whereas increased false positives would decrease the specificity and overall power of the study.…”

“…Tight knees, poor portal placement, osteophytosis, or surgeon inexperience can lead to only the free edge of the caudal pole of the meniscus being visualized 12 . The meniscal flounce, a fold in the free, unanchored inner edge of the medial meniscus, 13,14 is a common arthroscopic finding in people and dogs. Its presence is thought to be related to the anatomic configuration of fibers present in the meniscus that allow hoop stress to be exerted during weight bearing 13 .…”