Association of the Coronal Lateral Collateral Ligament Sign in ACL-Deficient Knees With Greater Anterior Tibial Translation and Femorotibial Rotation in Adults and Adolescents

Background: The coronal lateral collateral ligament (LCL) sign (the entire LCL being seen in 1 coronal slice on a magnetic resonance imaging [MRI] scan), is a new secondary sign of anterior cruciate ligament (ACL) tear. Purpose: To (1) evaluate the coronal LCL sign in adults with ACL tears and (2) compare the magnitude of the MRI scan parameters between adolescent and adult ACL-deficient knees with positive coronal LCL signs. Study Design: Cross-sectional study; Level of evidence: 3. Methods: We retrospectively reviewed patients who underwent ACL reconstruction between February 1, 2013, and May 31, 2021, and divided them into adolescent (10-18 years) and adult (>18 years) groups. Tibial translation, femorotibial rotation, and presence of the coronal LCL sign were evaluated using MRI. The static femorotibial position parameters were also compared between positive and negative coronal LCL sign groups. Independent Student t tests were used to identify statistically significant differences for continuous variables, whereas the categorical variables were compared using the chi-square test. Results: A total of 65 adolescents and 300 adults with ACL tears were identified. The coronal LCL sign was present in a similar percentage of adolescents and adults with ACL tears (57% vs 58%; P =.873). The anterior tibial translation (ATT) in patients with positive coronal LCL signs (adolescents, 7.9 ± 3.4 mm; adults, 6.6 ± 3.5 mm) was significantly greater compared with those with negative signs (adolescents, 1.5 ± 2.6 mm, P <.001; adults, 2.3 ± 4.2 mm, P <.001). Femorotibial rotation was also statistically greater in positive coronal LCL sign groups (adolescents, 6.4°± 5.6°; adults, 7.0°± 5.0°) compared with negative sign groups (adolescents, 0.7°± 4.7°, P <.001; adults, 3.5°± 4.2°, P <.001). Conclusion: The occurrence of the coronal LCL sign on MRI scans was comparable between adolescents and adults with ACL-deficient knees. The presence of the LCL sign was associated with a greater ATT and femorotibial rotation in both adolescents and adults with ACL tears.