桡尺远侧关节在体MRI运动学研究

目的　利用MRI轴位图像分析正常桡尺远侧关节（DRUJ）旋转运动。 方法　健康志愿者30名（男、女各15名），共60个正常DRUJ，在腕关节完全旋外、旋外60 °、旋外30 °、中立位、旋内30 °、旋内60 °及完全旋内7个体位行DRUJ的MRI扫描。在DRUJ轴位图上，选取桡骨乙状切迹掌侧顶点（A）及背侧顶点（B）作一连线，利用工作站工具取得尺骨头中心点（C），过C点作AB垂线，相交于D点，计算AD/AB比值（桡尺比值）；尺骨头-尺骨茎突背侧缘顶点E、F连线，测量EF与AB相交指向掌侧夹角（桡尺夹角）；由两名放射科医生独立完成测量、取其平均值，并评价该方法可信度。 结果　60个正常DRUJ完全旋外、旋外60°、旋外30°、中立位、旋内30°、旋内60°及完全旋内桡尺比值分别为（0.29±0.05），（0.36±0.06），（0.42±0.07），（0.49±0.05），（0.53±0.06），（0.56±0.06），（0.61±0.07）；桡尺夹角分别为（38.41±3.71）°，（48.74±5.54）°，（63.31±4.98）°，（105.56±5.63）°，（138.68±6.04）°，（162.45±6.00）°，（178.46±2.09）°。桡尺比值与桡尺夹角呈正相关，有统计学意义（r=0.97，P<0.05），腕关节从完全旋外向完全旋内旋转过程中，桡尺比值随桡尺夹角增大而增大。不同体位两项测量指标观察者间相关系数（ICC）范围为0.83~0.96。 结论　通过建立DRUJ在不同体位下桡骨的不同旋转角度所对应桡尺比值正常范围，可以为桡尺远侧关节不稳的诊断提供更多参考依据。

Kinesiology analysis of distal radioulnar joint rotation by utilizing magnetic resonance imaging

Objective　To analyze the normal distal radioulnar joint (DRUJ) rotation by utilizing the magnetic resonance imaging on axial imaging.　Methods　Axial magnetic resonance images at the bilateral DRUJ of 30 healthy volunteers (15 males, 15 females) were examined in seven rotational positions: maximum supination, 60 ° supination, 30 ° supination, neutral, 30 ° pronation, 60 ° pronation and maximum pronation. A line (AB) was drawn from the volar margin (A) and dorsal margin (B) of the sigmoid notch. The center of the ulnar head (C) was mrked using the workstation tools. A line (AD) perpendicular to this line (AB) was drawn to the center of the ulnar head (C). The point across the AB line was regarded as D. The AD/AB ratio was calculated, which was defined as the radioulnar ratio (RUR). A straight line at the apex of the dorsal edge of the ulnar head (E) and the ulnar styloid process (F) was drawn, and the palmar angle (radioulnar angle, RUA) at which straight line EF intersects straight line AB was measured. The measurement and calculation of average value were completed independently by two radiologists then the credibility of the method was evaluated.　Results　The RUR values of maximum supination, 60 ° supination, 30 ° supination, neutral, 30 °pronation, 60 °pronation and maximum pronation were (0.29±0.05), (0.36±0.06), (0.42±0.07), (0.49±0.05), (0.53±0.06), (0.56±0.06), (0.61±0.07) respectively, then the RUA were (38.41±3.71)°, (48.74±5.54)°, (63.31±4.98)°, (105.56±5.63)°, (138.68±6.04)°, (162.45±6.00)°, (178.46±2.09°) respectively. RUR was positively correlated with RUA and there were statistical difference between them (r=0.97，P<0.05). With the increasing of RUA, the RUR also increased during the process of wrists joints rotation from maximum supination to maximum pronation. The intraclass correlation coefficient (ICC) of RUR and RUA ranged from 0.83 to 0.96 under the above different positions.　Conclusions　By establishing the normal range of RUR of DRUJ at different rotation angles, more data could be provided for the diagnose of the instability of distal radioulnar joint.