Arthroscopically occult meniscotibial instability persists despite systematic transcondylar assessment: Incidence and associated factors during ACL reconstruction.

INTRODUCTION: Medial meniscus ramp lesions are recognized contributors to knee instability in anterior cruciate ligament (ACL)-injured knees. However, some knees may demonstrate functional instability at the meniscotibial attachment without visible structural disruption on arthroscopic inspection. The purpose of this study was to determine the incidence of probe-detected meniscotibial instability in knees without a visible ramp lesion on transcondylar inspection and to identify associated factors. METHODS: Patients who underwent primary ACL reconstruction between January 2021 and January 2026 were retrospectively reviewed. The ramp region was evaluated using a standardized transcondylar view, followed by systematic probing. Meniscotibial instability was defined as abnormal mobility of the posterior horn of the medial meniscus at the meniscotibial attachment in the absence of visible structural disruption. Multivariable logistic regression and receiver operating characteristic (ROC) analyses were performed. RESULTS: Of 171 patients, 113 met eligibility criteria. Forty-three had visible ramp lesions, leaving 70 for analysis. Meniscotibial instability was identified in 29 of 70 patients (41.4%). Preoperative side-to-side difference (SSD) in anterior tibial translation (OR, 1.81; P = 0.0024) and reduced ramp vascularity (OR, 3.36; P = 0.047) were independently associated with instability. An SSD cutoff of 5.0 mm showed acceptable discrimination (AUC, 0.734). CONCLUSION: Meniscotibial instability may be present despite normal arthroscopic appearance of the ramp region and is associated with increased preoperative instability. Systematic probing is essential to identify this occult functional abnormality.