Department of Orthopedic Surgery, Myongji Hospital, Goyang-si, Republic of Korea.
Department of Orthopedic Surgery, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, Republic of Korea.
Knee Surg Sports Traumatol Arthrosc. 2018 Aug;26(8):2317-2323. doi: 10.1007/s00167-017-4704-6. Epub 2017 Sep 11.
MRI evaluation of torn lateral meniscus was compared with arthroscopy. This study calculates the sensitivity, specificity, and accuracy of MRI in determining the presence or absence of discoid lateral meniscus (DLM) for different tear types.
MR imaging of 156 knees with arthroscopically confirmed lateral meniscus tears was analysed. There were 78 knees (70 patients) in non-DLM group and 78 knees (74 patients) in DLM group on arthroscopy as the reference standard. The presence of DLM on MRI was determined by an orthopaedic surgeon and a radiologist, who were blinded to the arthroscopic findings. The presence of discoid meniscus on MRI was determined by coronal and sagittal measurements, considering the tear pattern of lateral meniscus. The tear pattern was categorized into six types based on arthroscopic findings: horizontal, longitudinal, radial, combined radial, degenerative, and complex tear. The sensitivity, specificity, and accuracy of MRI were calculated for each type of lateral meniscus tear. In addition, we analysed the reason for non-detection of discoid meniscus on preoperative MRI.
The sensitivity for determining the presence of discoid meniscus was 58% for radial tear, 57% for combined radial tear, and 65% for longitudinal tear, whereas the specificity was 100% for all tear groups. In the presence of radial or longitudinal tear, the accuracy of MRI was significantly lower than having no radial and longitudinal tear (p < 0.001). The presence of discoid meniscus was not recognized on MRI because of large radial tear (12 knees), deformed bucket-handle tear (6 knees), and inverted flap tear (3 knees).
MRI was not successful in determining the presence or absence of DLM in radial tear, combined radial tear, and longitudinal tear. When there are large radial tear, deformed bucket-handle tear, and inverted flap tear in lateral meniscus, it is recommended to consider the possibility of DLM. This information can help to make accurate diagnosis of DLM, which allows appropriate surgical planning and facilitates patient's information on poor prognosis of DLM.
Level I.
将 MRI 评估外侧半月板撕裂与关节镜检查进行比较。本研究计算了 MRI 确定盘状外侧半月板（DLM）存在或不存在不同撕裂类型的敏感性、特异性和准确性。
对 156 例经关节镜证实的外侧半月板撕裂的 MRI 影像进行分析。在关节镜检查中，非 DLM 组有 78 例（70 例患者），DLM 组有 78 例（74 例患者）作为参考标准。MRI 上 DLM 的存在由一名矫形外科医生和一名放射科医生确定，他们对关节镜检查结果不知情。MRI 上盘状半月板的存在通过冠状面和矢状面测量确定，考虑到外侧半月板的撕裂模式。根据关节镜检查结果，将撕裂模式分为 6 种类型：水平型、纵向型、放射状、复合放射状、退行性和复杂撕裂。计算每种外侧半月板撕裂的 MRI 敏感性、特异性和准确性。此外，我们还分析了术前 MRI 未能检测到盘状半月板的原因。
确定 DLM 存在的敏感性分别为放射状撕裂 58%、复合放射状撕裂 57%和纵向撕裂 65%，而特异性在所有撕裂组均为 100%。在存在放射状或纵向撕裂的情况下，MRI 的准确性明显低于没有放射状和纵向撕裂（p<0.001）。MRI 未能识别盘状半月板的存在，原因是较大的放射状撕裂（12 例）、变形的桶柄撕裂（6 例）和倒置瓣撕裂（3 例）。
MRI 无法确定放射状撕裂、复合放射状撕裂和纵向撕裂中 DLM 的存在或不存在。当外侧半月板存在大的放射状撕裂、变形的桶柄撕裂和倒置瓣撕裂时，建议考虑存在 DLM 的可能性。这些信息可以帮助准确诊断 DLM，从而进行适当的手术计划，并为患者提供关于 DLM 预后不良的信息。
I 级。
