The Fate of Meniscus Tears Left In Situ at the Time of Anterior Cruciate Ligament Reconstruction: A 6-Year Follow-up Study From the MOON Cohort.

BACKGROUND

The management of meniscus tears identified at the time of primary anterior cruciate ligament (ACL) reconstruction is highly variable and includes repair, meniscectomy, and nontreatment.

HYPOTHESIS/PURPOSE: The purpose of this study was to determine the reoperation rate for meniscus tears left untreated at the time of ACL reconstruction with a minimum follow-up of 6 years. The hypothesis was that small peripheral tears identified at the time of ACL reconstruction managed with "no treatment" would have successful clinical outcomes.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients with meniscus tears left untreated at the time of primary ACL reconstruction were identified from a multicenter study group with a minimum 6-year follow-up. Patient, tear, and reoperation data were obtained for analysis. The need for reoperation was used as the primary endpoint, with analysis performed to determine patient and tear characteristics associated with reoperation.

RESULTS

There were 194 patients with 208 meniscus tears (71 medial, 137 lateral) left in situ without treatment with a complete follow-up for analysis. Of these, 97.8% of lateral and 94.4% of medial untreated tears required no reoperation. Sixteen tears (7.7%) left in situ without treatment underwent subsequent reoperation: 9 tears (4.3%) underwent reoperation in the setting of revision ACL reconstruction, and 7 tears (3.4%) underwent reoperation for an isolated meniscus injury. The patient age was significantly lower in patients requiring reoperation, while tears measuring ≥10 mm more frequently required reoperation.

CONCLUSION

Lateral and medial meniscus tears left in situ at the time of ACL reconstruction did not require reoperation at a minimum 6-year follow-up for 97.8% and 94.4% of tears, respectively. These findings re-emphasize the low reoperation rate after the nontreatment of small, peripheral lateral meniscus tears while noting less predictable results for medial meniscus tears left without treatment.