目的　通过对骶髂关节周围解剖和CT重建进行研究，明确骶髂关节前路钢板螺钉固定的安全区。  方法　选15具成人尸体骨盆，做以下测量：L4、L5神经前支到骶髂关节线的水平距离及到骶骨翼的垂直距离；L4、L5神经根从椎间孔到真骨盆缘的长度及其中点直径；在CT冠状位二维重建中测量：骶髂关节切线与矢状面的夹角；骶髂关节骶骨侧宽度。  结果    L4、L5神经根从上到下距离骶髂关节线的距离逐渐减小，最宽处分别为（2.1±0.2）cm和（2.6±0.2）cm，最窄处分别为（1.2±0.2）cm和（1.5±0.2）cm；L4神经根距离骶骨面的垂直距离从上到下也是逐渐减少，最高处约10 mm，最低处则紧贴骨膜，L5神经根前支则全长紧贴于骨膜；从出椎间孔到真骨盆边缘L4神经根的长度为（7.4±0.8）cm,其中点直径为（2.7±0.8）　mm；L5神经根的长度为（3.9±0.5）cm,其中点直径为（7.3±1.4）mm；CT重建中观察结果：骶髂关节面与矢状面的角度约为30度；骶髂关节线到椎管外侧缘的距离从上到下逐渐减少，最宽处3.3 cm，最窄处2.3 cm；到椎间孔外侧缘的距离较为恒定，约2 cm；　结论　骶髂关节前路钢板螺钉的安全区：钢板应置于骶髂关节的中、上部，上钢板向骶骨侧剥离不超过2.5 cm，下钢板向骶骨剥离不超过1.5 cm，螺钉内倾30°植入。

Objective    To explore the surgical safe zone of the anterior plate and screw fixation for treating sacroiliac joint fracture and dislocation.   Methods    15 normal pelvic specimens were used. The horizontal distances from L4, L5 anterior roots to the sacroiliac joint, the vertical distances from L4, L5 roots to sacral wing, the distances from the intervertebral foreman of L4, L5 to the rim of true pelvis, and the diameter of the L4, L5 roots were measured respectively. On two dimensional pelvic coronal reconstruction images, the angle between sacroiliac joint and sagittal plane, the width of the sacrum were tested.    Results    The horizontal distance from the lateral side of the L4, L5 roots to the sacroiliac joint gradually diminished from the top to the bottom, with the widest of (2.1±0.2）and （2.7±0.2）cm  respectively, and the narrowest of （1.2±0.2）cm and（1.5±0.2）cm respectively. The vertical distances between the L4 root and the sacrum also diminished gradually from the intervertebral foramen to the rim of the pelvis. The length of the L4 and L5 roots were（7.4±0.8）cm and 3.9±0.5）cm, and the diameters  (2.7±0.8）mm and （7.3±1.4）mm respectively. On CT reconstruction images, the angle between sacroiliac joint and sagittal plane was about 30°, and the distance from the sacroiliac joint to the lateral side of the spinal canal changed from 3.3cm to 2.3cm, the horizontal distance from the sacroiliac joint to the lateral side of the intervertebral foramen was about 2cm.    Conclusions    The surgical safe zone of the anterior plate and screw fixation for treating sacroiliac joint fracture and/or dislocation can be defined as the follows: the upper and lower plates places on the upper third of the sacroiliac joint, with the limited exposure range of 2.5cm, or the middle third of the sacroiliac joint, with the limited exposure range of 1.5cm. The screw should be inserted with introversional angle of 300.