Purpose

To investigate the associations between the preoperative MRI ?ndings suggestive of meniscal instability and the intraoperative ?nding of peripheral rim instability (PRI) in patients with no-shift-type complete discoid lateral meniscus (CDLM).

Methods

The records of 47 patients diagnosed with no-shift-type CDLM who underwent arthroscopic surgery were reviewed. We evaluated MRI findings of increased intrameniscal signal, anterior parameniscal soft-tissue edema, linear fluid signal at the anterior meniscal margin, bulging of the meniscal margin, absence of popliteomeniscal fascicles, hiatus widening on routine MRI. The positive predictive value (PPV), sensitivity, and specificity of these findings in predicting PRI were calculated; PRI was further investigated according to anterior and posterior location.

Results

Linear fluid signal at the anterior meniscal margin and bulging had high PPV, specificity (P=.001 and =.003, respectively) for overall of PRI. The presence of either anterior parameniscal soft-tissue edema or linear fluid signal at the anterior meniscal margin predicted anterior PRI with high PPV, sensitivity, and specificity. BEither bulging of the meniscal margin (P=.014) had high specificity but low PPV and sensitivity in predicting posterior PRI.

Conclusions

A linear fluid signal at the anterior meniscus and anterior parameniscal soft-tissue edema were important signs of anterior PRI, whereas bulging of the margin had high specificity but low sensitivity in detecting posterior PRI on routine MRI of no-shift-type CDLM.