PURPOSE To determine the prevalence of a deep lateral femoral notch sign (LFNS) in magnetic resonance imaging (MRI) in patients with anterior cruciate ligament (ACL) and concomitant posterior root tears of the lateral meniscus (PLRT). METHODS A retrospective chart review was conducted to identify all patients undergoing ACL reconstruction between 2016 and 2018. Based on the arthroscopic appearance of the lateral meniscus, patients were assorted to one of three groups: isolated ACL tear (ACL-Group), ACL tear with concomitant lateral meniscus tear not involving the posterolateral root (Meniscus-Group), and ACL tear with concomitant PLRT (PLRT-Group). Incidence and depth of a LFNS on preoperative MRI was compared between the three cohorts. RESULTS 115 patients (mean age: 29.5 ± 11.3 years) were included in the study, with 58 patients (50.4%) assorted to the ACL-Group, 24 patients (20.9%) to the Meniscus-Group, and 33 patients (28.7%) to the PLRT-Group. The prevalence of a LFNS was significantly higher in the PLRT-Group (39.4%), when compared to the ACL- (5.2%) or Meniscus-Groups (25.0%; p < 0.001, respectively). Additionally, logistic regression analysis demonstrated that patients with PLRT were 5.3 times more likely to have a LFNS as compared to those without a lateral root tear (p < 0.001). CONCLUSION In patients with ACL tears, the presence of a LFNS on preoperative MRI may be predictive for a PLRT. As the LFNS occurs in almost 40% of the patients with combined ACL tears and PLRT, the LFNS may be a useful secondary diagnostic finding in early MRI diagnostic. Identifying PLRT on MRI is clinically relevant, as it prevents misdiagnosis and facilitates surgical decision-making, thus avoiding subsequent delayed treatment. LEVEL OF EVIDENCE Level IV.

中文翻译：

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前交叉韧带（ACL）并伴有半月板外侧后根撕裂的患者深部股骨切迹的发生率很高。

目的确定前交叉韧带（ACL）和伴有外侧半月板后根撕裂（PLRT）的患者在磁共振成像（MRI）中股骨深凹口征（LFNS）的患病率。方法采用回顾性图表回顾法，确定2016年至2018年之间所有接受ACL重建的患者。根据关节镜检查外侧半月板的外观，将患者分为三组之一：孤立ACL撕裂（ACL-Group），ACL撕裂与不伴有后外侧根的半月板伴有半月板撕裂（Meniscus-Group），伴有PLRT的ACL伴有撕裂（PLRT-Group）。比较了这三个队列中LFNS在术前MRI上的发生率和深度。结果该研究包括115例患者（平均年龄：29.5±11.3岁），其中58例患者（50例。ACL组为4％），半月板组为24例（20.9％），PLRT组为33例（28.7％）。与ACL-组（5.2％）或半月板组（25.0％； p <0.001）相比，PLRT组的LFNS患病率显着更高（39.4％）。此外，逻辑回归分析表明，与无侧根撕裂的患者相比，患有PLRT的患者患LFNS的可能性高5.3倍（p <0.001）。结论对于ACL眼泪患者，术前MRI上存在LFNS可能是PLRT的预兆。由于LFNS几乎在40％的合并ACL泪液和PLRT的患者中发生，因此LFNS在早期MRI诊断中可能是有用的辅助诊断结果。在MRI上识别PLRT具有临床意义，因为它可以防止误诊并有助于手术决策，从而避免了后续的延迟治疗。证据级别IV。