膝关节伸屈过程中胫骨旋转的动态磁共振成像评价

Evaluation of the Rotation of the Tibia with Kinematic MR Imaging

目的 用动态磁共振检查膝关节伸屈过程中胫骨的旋转,并探讨其临床意义。方法 对30名健康志愿者在0°-40°范围内屈曲和伸直膝关节时作横断面胫骨平台成像。将每次横断面成像重叠,测量胫骨内外旋转的角度。结果 通过测量显示,随着屈膝时胫骨向内旋转,伸直时胫骨外旋,胫骨内外旋转角度无显著性差别(P>0.05),未发现男女性别及左右膝关节旋转角度的差异。膝关节屈曲0°-24°以内与屈曲24°-40°胫骨旋转有显著性差别(P<0.01)。结论 正常人的胫骨随着膝关节的伸屈具有旋转功能,认为主要是由韧带和关节囊结构及股骨髁的几何形状决定的;同时这种胫骨旋转又形成旋转回旋机制,使膝关节更加稳定。

Objective To measure the values of the rotation of the tibia between 40°of flexion and 0°of extension. Methods Thirty volunteers with healthy knees were examined by kinematic MR using an extremity MR system. The knees were imaged in the transverse plane when flexing from 0°about 40°of flexion and extending from about 40°of flexion to a straight position, and then each value of the rotation of the tibium was measured. Results From measurement it is found that the tibia normally rotates inwardly in relation to the femour when the knee went into flexion while rotating outwardly as the knee extended from flexion position. From the values obtained from this study we found no significant difference between tibial inward rotation and outward rotation as well as male and female, left and right knee.But a significant difference in the tibial rotation between 0°-24°of flexion of knee and 24°-40°was found (P<0.01). Conclusion Normally, as the knee extends and flexes the tibia rotates externally and internally. At this time a screw-home mechanism occurs. This increases stability of the knee. Rotatory stabitity of the knee joint is provided primarily by the ligamentous and capsular structures and by the geometry of the condyles. Muscle activity also plays some part.