Inoue Jumpei, Nukuto Koji, Park Yunseo L, Kamada Kohei, Dias Karina, Cong Ting, Musahl Volker
UPMC Freddie Fu Sports Medicine Center, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA; Department of Orthopaedic Surgery, Nagoya Tokushukai General Hospital, Kasugai, Aichi, Japan.
UPMC Freddie Fu Sports Medicine Center, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA; Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan.
J ISAKOS. 2025 Sep 8;15:100999. doi: 10.1016/j.jisako.2025.100999.
The deep lateral femoral notch sign, observed in some anterior cruciate ligament (ACL) injuries, may result from valgus-compressive forces and anterior tibial translation. Since combined ACL and medial collateral ligament (MCL) injuries often involve high valgus torque, we hypothesized an association between MCL tears and the presence of a deep lateral femoral notch sign.
We conducted a retrospective cohort study of skeletally mature patients (≥14 years) who underwent primary ACL reconstruction (ACLR) and had preoperative MRIs within 3 weeks of injury. Patients were grouped by the presence of a deep lateral femoral notch sign (≥2 mm depth). Superficial and deep MCL tears were graded via MRI. Demographics and meniscus surgery data were collected. Univariable and multivariable analyses were used to identify factors associated with the deep lateral femoral notch sign (P < .050).
Among 590 included patients, 104 (17.6%) had a deep lateral femoral notch sign. Intra- and inter-observer reliability for notch depth and MCL grading showed near-perfect agreement (κ > 0.8). Multivariable analysis identified superficial MCL tear, younger age, and medial posterior tibial bone bruise as independent predictors of a deep lateral femoral notch sign (P < .001 for all). When stratifying superficial MCL tears, 12.6% of grade 0/I cases and 34.6% of grade II/III cases had deep lateral femoral notch signs. The sign showed 34.6% sensitivity, 87.4% specificity, and an odds ratio of 3.68 (95% CI, 2.35-5.77) for predicting grade II/III superficial MCL tears.
In acute ACL injuries, the deep lateral femoral notch sign is associated with grade II/III superficial MCL tears, showing high specificity and a 3.7-fold increased risk. Its presence should prompt careful assessment of MCL-related instability to optimize patient outcomes.
Level IV, retrospective cohort study.
