正常膝关节后外侧角MRI表现

目的 探讨正常膝关节后外侧角(PLC)解剖的MRI表现及其临床应用价值。方法 采用前瞻性研究方法。2016年5—6月在苏州大学附属第三医院招募16名青年志愿者进行双膝关节MR检查,其中男9名、女7名,年龄22～30岁;两侧膝关节无手术史及外伤史,且体格检查正常。受试体位:仰卧、膝关节伸直并轻度外旋10°～15°;扫描序列:斜矢状位快速自旋回波T₁WI、T₂WI,冠状位、斜矢状位及轴位质子密度加权成像(PDWI);观察分析组成PLC的腓侧副韧带、腘肌腱、腘腓韧带、豆腓韧带、弓状韧带的形态、止点、走行、信号强度及其与毗邻结构的位置关系。结果 PDWI可以清晰显示呈低信号强度的正常PLC的特殊结构,主要包括腓侧副韧带、腘肌腱、腘腓韧带、弓状韧带、豆腓韧带,显示率分别为100%(32/32,侧)、100%(32/32,侧)、87.5%(28/32,侧)、81.3%(26/32,侧)和37.5%(12/32,侧)。腓侧副韧带、腘肌腱位置及走行固定。腓侧副韧带全长(50.88±4.72)mm,中点宽(4.72±0.33)mm、厚(2.55±0.40)mm;腘肌腱全长(45.31±1.66)mm,腘肌裂孔处宽(3.26±0.39)mm、厚(3.15±0.26)mm;腘腓韧带全长(11.66±0.78)mm,中点宽(3.24±0.32)mm、厚(1.24±0.11)mm;弓状韧带及豆腓韧带显示率不高、变异较多,韧带起止点、大小、形态因个体差异可有所不同。左右侧腓侧副韧带、腘肌腱、腘腓韧带的长度、宽度、厚度比较,差异均无统计学意义(P值均＞0.05);男女性腓侧副韧带长度及厚度、腘肌腱长度及宽度比较,差异有均有统计学意义(P值均<0.05)。结论 熟悉PLC的正常解剖结构能够帮助我们发现该区域的细微异常改变,了解其正常及损伤的磁共振表现,提高放射科医师对PLC损伤的诊断能力。

MRI of the posterolateral corner of the normal knee

Objective To investigate the MRI findings of the posterolateral corner(PLC) of the normal knee joint and its clinical significance.Methods A prospective study was conducted in 16 young volunteers who were recruited from the Third Affiliated Hospital of Soochow University between May 2016 and June 2016 for MRI examination of the knee, including 9 males and 7 females, aged 22 to 30 years. There was no operative history and trauma and the physical examinations were normal on both sides of the knee. All volunteers were supine and the knee unbent with 10°-15° of slight external rotation. The MRI sequences, including conventional oblique sagittal turbo spin echo (TSE) T₁WI, T₂WI, and coronal, oblique sagittal and axial proton density weighted image(PDWI) sequence, were scanned for observation and the morphologic characteristics, attachment points, route, signal strength and the relationship with adjacent structures of the posterolateral corner of the knee, which was composed of fibular collateral ligament, popliteal tendon, popliteofibular ligament, fabellofibular ligament and arcuate ligament were analyzed.Results The specific components of the posterolateral corner of the normal knee that could be clearly identified on PDWI included the fibular collateral ligament, popliteus tendon, popliteofibular ligament, arcuate ligament and fabellofibular ligament. Meanwhile, the displaying rate was 100%(32/32), 100%(32/32), 87.5%(28/32), 81.3%(26/32) and 37.5%(12/32), respectively.The location and route of the fibular collateral ligament was fixed, and this ligament was on average (50.88±4.72) mm in length and, (4.72±0.33) mm in width of the midpoint and (2.55±0.40) mm in thickness.The popliteal tendon was (45.31±1.66) mm in length, (3.15±0.26) mm in thickness and (3.26±0.39) mm in width at the popliteal hiatus. The popliteofibular ligament was (11.66±0.78) mm in length, (3.24±0.32) mm in width of the midpoint and (1.24±0.11) mm in thickness. The display rate of arcuate ligament and fabellofibular ligament was not high in MRI, and appeared with some variability in attachment point, size, morphologic characteristics due to individual differences. There was no significant difference in the length, width and thickness of the fibular collateral ligament,popliteus tendon, popliteofibular ligament between both sides of the knee (all P values>0.05), while there was significant difference in the length and thickness of the fibular collateral ligament as well as the length and width of the popliteal tendon between males and females (all P values<0.05).Conclusions Being familiar with the anatomy and the normal magnetic resonance of PLC is helpful to discover the subtle abnormal changes and improve the radiologists' ability for diagnosing the PLC injuries.