Chen Xu-Xu, Li Jian, Wang Tao, Zhao Yang, Kang Hui
Department of Sports Medicine, Hong-Hui Hospital, Xi'an Jiaotong University College of Medicine, Xi'an, Shaanxi 710054, China.
Chin Med J (Engl). 2017 Mar 5;130(5):536-541. doi: 10.4103/0366-6999.200535.
Discoid lateral meniscus was a common meniscal dysplasia and was predisposed to tear. There were some anatomical knee variants in patients with discoid lateral meniscus. The aim of this study was to analyze the relationship between anatomical knee variants and discoid lateral meniscal tears.
There were totally 125 cases of discoid lateral meniscus enrolled in this study from February 2008 to December 2013. Eighty-seven patients who underwent arthroscopic surgery for right torn discoid lateral meniscus were enrolled in the torn group. An additional 38 patients who were incidentally identified as having intact discoid lateral menisci on magnetic resonance imaging (MRI) findings were included in the control group. All patients were evaluated for anatomical knee variants on plain radiographs, including lateral joint space distance, height of the lateral tibial spine, height of the fibular head, obliquity of the lateral tibial plateau, squaring of the lateral femoral condyle, cupping of the lateral tibial plateau, lateral femoral condylar notch, and condylar cutoff sign. The relationship between anatomical variants and meniscal tear was evaluated. These anatomical variants in cases with complete discoid meniscus were also compared with those in cases with incomplete discoid meniscus.
There were no significant differences between the two groups in lateral joint space distance (P = 0.528), height of the lateral tibial spine (P = 0.927), height of the fibular head (P = 0.684), obliquity of the lateral tibial plateau (P = 0.672), and the positive rates of squaring of the lateral femoral condyle (P = 0.665), cupping of the lateral tibial plateau (P = 0.239), and lateral femoral condylar notch (P = 0.624). The condylar cutoff sign was significantly different between the two groups, with the prominence ratio in the torn group being smaller than that in the control group (0.74 ± 0.11 vs. 0.81 ± 0.04, P = 0.049). With the decision value of the prominence ratio (0.78) in predicting discoid lateral meniscal tear, the sensitivity and specificity of the cutoff sign were 66% and 71%, respectively. There were no significant differences in radiographic variants between the complete and incomplete discoid lateral meniscal groups.
The condylar cutoff sign observed on the tunnel view of the radiograph is helpful in predicting meniscal tear in adult patients with discoid lateral meniscus. As for these patients, further MRI test is recommended.
盘状外侧半月板是一种常见的半月板发育异常，易发生撕裂。盘状外侧半月板患者存在一些膝关节解剖变异。本研究旨在分析膝关节解剖变异与盘状外侧半月板撕裂之间的关系。
2008年2月至2013年12月，本研究共纳入125例盘状外侧半月板患者。87例行右盘状外侧半月板撕裂关节镜手术的患者纳入撕裂组。另外38例经磁共振成像（MRI）检查偶然发现盘状外侧半月板完整的患者纳入对照组。所有患者均通过X线平片评估膝关节解剖变异，包括外侧关节间隙距离、外侧胫骨棘高度、腓骨头高度、外侧胫骨平台倾斜度、外侧股骨髁方形化、外侧胫骨平台杯状化、外侧股骨髁切迹以及髁突截断征。评估解剖变异与半月板撕裂之间的关系。还比较了完全盘状半月板病例与不完全盘状半月板病例的这些解剖变异情况。
两组在外侧关节间隙距离（P = 0.528）、外侧胫骨棘高度（P = 0.927）、腓骨头高度（P = 0.684）、外侧胫骨平台倾斜度（P = 0.672）、外侧股骨髁方形化阳性率（P = 0.665）、外侧胫骨平台杯状化阳性率（P = 0.239）以及外侧股骨髁切迹阳性率（P = 0.624）方面均无显著差异。两组髁突截断征存在显著差异，撕裂组的突出率低于对照组（0.74±0.11对0.81±0.04，P = 0.049）。以突出率的判定值（0.78）预测盘状外侧半月板撕裂时，截断征的敏感性和特异性分别为66%和71%。完全盘状外侧半月板组与不完全盘状外侧半月板组在影像学变异方面无显著差异。
X线片隧道位观察到的髁突截断征有助于预测成年盘状外侧半月板患者的半月板撕裂。对于这些患者，建议进一步行MRI检查。
