BACKGROUND The lateral meniscus posterior root (LMPR) lesion further decreases dynamic knee stability after anterior cruciate ligament (ACL) injury owing to the loss of the "wedge effect" maintained by the posterior horn of the lateral meniscus. However, the effect of LMPR lesions on the static tibiofemoral relationship in extension after ACL injuries is not determined. PURPOSE To (1) determine the effect of LMPR lesions on anterior tibial subluxation of the lateral compartment (ATSLC) in extension in patients with ACL injuries and to (2) identify the LMPR-related factors associated with excessive ATSLC in extension. STUDY DESIGN Cohort study; Level of evidence, 3. METHODS Between January 2015 and December 2017, 405 consecutive patients with diagnosed ACL injuries who underwent primary ACL reconstructions were retrospectively reviewed. Among them, 45 patients with combined ACL injuries and LMPR lesions (ACL+LMPR group) and 51 patients with isolated ACL injuries (ACL group) were identified. Values of ATSLC in extension were measured on preoperative supine magnetic resonance imaging and classified into high grade (≥6 mm) and low grade (<6 mm). The mean ATSLC in extension and the proportion of patients with high-grade ATSLC in extension were compared between the groups by univariate analysis. In the ACL+LMPR group, predictors of high-grade ATSLC in extension-including age, sex, body mass index, affected side, cause of injury, period from injury (<12 or ≥12 weeks), LMPR lesion pattern (radial tear or root avulsion), and meniscofemoral ligament integrity (intact or impaired)-were assessed by univariate analysis and multivariate logistic regression analysis. RESULTS The mean ATSLC in extension in the ACL+LMPR group was significantly greater than that in the ACL group (5.6 mm vs 3.1 mm; P = .001). The proportion of patients with high-grade ATSLC in extension in the ACL+LMPR group was also significantly larger than that in the ACL group (44.4% vs 15.7%; P = .002). In addition, the root avulsion (instead of radial tear) (odds ratio, 28.750; 95% CI, 2.344-352.549; P = .009) and the period from injury ≥12 weeks (odds ratio, 17.095; 95% CI, 1.207-242.101; P = .036) were determined to be the 2 independent predictors of high-grade ATSLC in extension. However, age, sex, body mass index, affected side, cause of injury, and meniscofemoral ligament integrity were not. CONCLUSION After ACL injuries, concomitant LMPR lesion further increased ATSLC in extension. Chronic LMPR avulsion was associated with high-grade ATSLC in extension.

中文翻译：

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外侧半月板后根病变影响前交叉韧带损伤后侧脑室的胫骨半脱位。

背景技术外侧半月板后根（LMPR）损伤由于失去了由外侧半月板后角保持的“楔效应”而进一步降低了前十字韧带（ACL）损伤后的动态膝关节稳定性。但是，尚未确定LMPR病变对ACL损伤后延伸的静态胫股关系的影响。目的（1）确定LMPR病变对ACL损伤患者伸展中外侧隔室（ATSLC）胫前半脱位的影响，以及（2）识别与过度伸展ATSLC相关的LMPR相关因素。研究设计队列研究；证据等级，3。方法2015年1月至2017年12月，对405例经诊断为ACL损伤的连续患者进行了原发性ACL重建。其中，鉴定出45例合并ACL损伤和LMPR病变的患者（ACL + LMPR组）和51例单纯ACL损伤的患者（ACL组）。在术前仰卧磁共振成像中测量ATSLC的扩展值，并分为高等级（≥6mm）和低等级（<6 mm）。通过单因素分析比较了两组之间的平均ATSLC扩展和高级别ATSLC扩展患者的比例。在ACL + LMPR组中，可预测高级ATSLC的延伸范围，包括年龄，性别，体重指数，患侧，受伤原因，受伤时间（<12或≥12周），LMPR病变模式（放射状撕裂）或根部撕脱）和（全部或受损的）粘膜股韧带完整性通过单变量分析和多因素逻辑回归分析进行评估。结果ACL + LMPR组的平均ATSLC伸展度明显高于ACL组（5.6毫米对3.1毫米； P = .001）。ACL + LMPR组中具有扩展性高级别ATSLC的患者比例也显着大于ACL组（44.4％对15.7％； P = .002）。此外，根部撕脱（而不是radial裂）（赔率，28.750； 95％CI，2.344-352.549； P = .009）和受伤期≥12周（赔率，17.095； 95％CI，1.207） -242.101； P = .036）被确定为扩展高级ATSLC的2个独立预测因子。但是，年龄，性别，体重指数，患侧，受伤原因和粘膜股韧带完整性均没有。结论ACL损伤后，伴随的LMPR病变进一步扩大了ATSLC的延伸范围。