Anterior Cruciate Ligament (ACL)-injured Knees with Meniscal Ramp Lesions Manifest Greater Anteroposterior and Rotatory Instability Compared with Isolated ACL-injured Knees

Purpose To investigate the effects of ramp lesion (RL) and its repair on knee instability in patients with anterior cruciate ligament (ACL) injury by quantitatively assessing anteroposterior and rotational knee instability before and after ACL reconstruction. Methods All primary double-bundle ACL reconstruction using hamstring autografts between 2016 and 2021 were evaluated retrospectively. Patients with RLs without other meniscal injuries were included in Group R, whereas those with isolated ACL injuries constituted Group C. RL was repaired using all-inside devices in all patients in Group R. Knee instability, including the amount of anterior tibial translation (ATT), and the acceleration and external rotational angular velocity of the knee joint (ERAV) during the pivot-shift test were assessed at the time of surgery. The pivot-shift test grade was recorded. Results A total of 73 patients were included in this study. Preoperatively, Group R (n=23) had significantly greater pivot-shift grades (P=.039), ATT (6.0 mm: Group R; 4.5 mm: Group C, P<.001), acceleration (6.8; 2.8, P=.037), and ERAV (3.9; 2.8, P=.001) than Group C (n=50). Intraoperatively, ATT (-1.0 mm; -1.0 mm, P<.001), acceleration (1.2; 1.1, P<.001), and ERAV (1.4; 1.2, P<.001) were significantly decreased compared with the preoperative values in both groups. No significant differences in these values were observed between Groups R and C. Conclusions ACL-injured knees accompanied by RLs exhibited significantly greater anteroposterior and rotatory instability than knees with isolated ACL injuries; increased knee instability can be effectively addressed by performing RL repair in conjunction with ACL reconstruction. The quantitative assessments employed—specifically measuring ATT, acceleration and ERAV during the pivot-shift test—have allowed us to delineate these aspects of knee instability with greater precision. Level of Evidence Level Ⅲ, retrospective comparative study.