Klinik für Orthopädie und Unfallchirurgie, Martin Luther Krankenhaus, Berlin, Germany.
Abteilung und Poliklinik für Sportorthopädie, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany.
Knee Surg Sports Traumatol Arthrosc. 2019 Oct;27(10):3311-3317. doi: 10.1007/s00167-018-5341-4. Epub 2019 Jan 3.
Extrusion of the medial meniscus evaluated on magnetic resonance imaging (MRI) has been described as indirect radiological sign for meniscus root tears. However, ultrasound detectable dynamic extrusion is observed in normal physiological settings. The aim of the present study was to analyze the dynamic meniscal extrusion using ultrasound (US) examination in patients with MRI-confirmed meniscal root tears. The hypothesis was that dynamic meniscus extrusion is reduced in patients with medial root tear but not in the healthy meniscus.
Twenty-five patients with a medial root lesion of the meniscus (group I) and 25 healthy controls (group II) were enrolled in this study. The medial meniscus extrusion (MME) of the index knee was determined using ultrasound (US) in supine position and under full weight bearing. Standard knee MRI was used for determining whether the patients were eligible for this study according to the inclusion and exclusion criteria, respectively.
In group I, the mean MME was 3.6 mm (± 1.0 mm) in supine position and 3.7 mm (± 0.9 mm) under full weight bearing according to US measurements. The mean Δ-extrusion was 0.1 mm (± 0.2 mm) and the ratio was 1.0 (± 0.1). Mean medial meniscus extrusion on MRI was 3.9 mm (± 0.9 mm). In group II, mean MME was 1.3 mm (± 0.3 mm) in supine position (US) and 2.3 mm (± 0.4 mm) under full weight bearing (US). The mean Δ-extrusion was 1.0 mm (± 0.4 mm) and the extrusion ratio was 1.8 (± 0.4). In this group, mean extrusion in MRI was 1.4 mm (± 0.7 mm). The difference in mean ultrasound Δ-extrusion, ratio, and MRI extrusion between both groups was statistically significant (p < 0.001).
Based on the results of dynamic ultrasound examination of the medial meniscus, medial root tear leads to significantly decreased dynamic medial displacement of the meniscus compared to healthy meniscus status. The absence of dynamic meniscus extrusion may be an indicator for medial meniscus root injury and could be detected using ultrasound ("dead meniscus sign").
III.
磁共振成像（MRI）上内侧半月板的挤出被描述为半月板根部撕裂的间接放射学征象。然而，在正常生理状态下可以观察到超声可检测到的动态挤出。本研究的目的是分析 MRI 证实的半月板根部撕裂患者的超声（US）检查中的动态半月板挤出。假设是内侧根部撕裂患者的动态半月板挤出减少，但健康的半月板没有。
本研究纳入 25 例内侧半月板根部病变患者（I 组）和 25 例健康对照者（II 组）。采用仰卧位和完全负重位下的超声（US）检查确定内侧半月板的内侧半月板挤出（MME）。标准膝关节 MRI 用于根据纳入和排除标准分别确定患者是否适合本研究。
在 I 组中，US 测量结果显示，仰卧位时 MME 平均为 3.6mm（±1.0mm），完全负重位时为 3.7mm（±0.9mm）。平均挤出增量为 0.1mm（±0.2mm），比值为 1.0（±0.1）。MRI 上内侧半月板的平均挤出量为 3.9mm（±0.9mm）。在 II 组中，仰卧位时 MME 平均为 1.3mm（±0.3mm）（US），完全负重位时为 2.3mm（±0.4mm）（US）。平均挤出增量为 1.0mm（±0.4mm），挤出比为 1.8（±0.4）。在该组中，MRI 上的平均挤出量为 1.4mm（±0.7mm）。两组之间的平均超声挤出增量、比值和 MRI 挤出的差异具有统计学意义（p<0.001）。
基于内侧半月板的动态超声检查结果，内侧半月板根部撕裂导致内侧半月板的动态内侧位移明显减少，与健康半月板状态相比。缺乏动态半月板挤出可能是内侧半月板根部损伤的一个指标，可以通过超声（“死半月板征”）检测到。
III 级。
