目的　通过对髋臼四边区三维重建模型进行解剖参数测量和从上方置入虚拟螺钉，明确四边区骨折螺钉固定的安全区域。  方法    用Mimics软件对50例（100侧）骨盆CT数据进行三维重建，切割出髋臼四边区三维模型，测量四边区解剖参数，确定置钉危险区域，并在四边区上界模拟置钉，计算其安全角度。    结果　P1螺钉最大后倾角男性为（7.63±5.47）°，女性为 （6.18±5.16）°，P5螺钉最大前倾角男性为（7.50±6.09）°，女性为（7.30±6.54）°，两者男女间差异均无统计学意义。P2、P4螺钉内外倾安全范围男性分别为（7.60±2.93）°、（16.88±5.61）°，女性分别为（7.96±2.98）°、（15.82±5.94）°，男女间差异均无统计学意义。男、女性分别有13侧及28侧P3螺钉安全范围很小，只能以固定角度置入，固定角度均值男性为（-0.22±2.87）°，女性为（-5.62±4.48）°，其差异有统计学意义。剩余59侧（男37侧，女22侧）P3螺钉安全范围男性为（5.39±2.60）°，女性为（4.06±2.58）°，其差异无统计学意义。   结论　P3为四边区上界最危险进钉点，距离起点约27 mm，若术前Mimics软件测量显示四边区骨质最薄处厚度男性小于4.47 mm，女性小于3.56 mm，则拧入长度小于14 mm或12 mm的短钉或空置。

Objective　To identify the safe zone for screws to fix fractures of acetabular quadrilateral plateby anatomical parameter measurement and virtual screws insertion at upper boundary of three-dimensional reconstruction quadrilateral plate model.　Methods　50 pelves(100 sides) including 25 females and 25 males were reconstructed in three-dimensional form and cut by Mimics software. The quadrilateral plate anatomical parameters were measured and the dangerous zone of screw insertion was determined；then the virtual screws were placed in the quadrilateral plate through different entry points at upper boundary,and the safe ranges of the screws were calculated.　Results　The maximum backward incline angles of screw P1 were （7.63±5.47）° in male and（6.18±5.16）° in female, and the maximum forward incline angles of screw P5 were（7.50±6.09）° in male and（7.30±6.54）° in female, both of them had no significant difference between genders. The inward and outward incline safe ranges of screw P2 and P4 were（7.60±2.93）° and （16.88±5.61）° in male and（7.96±2.98）° and（15.82±5.94）° in female, respectively. There were 13 sides in male and 28 sides in female whose safe range of screw P3 was extremely narrow that they have to be inserted at given angles, which were（-0.22±2.87）°in male and （-5.62±4.48）°in female, and the difference between male and female had statistical significance. The safe ranges of screw P3 of the remaining 59 sides were （5.39±2.60）° in male and（4.06±2.58）°  in female, with no significant difference between genders.　Conclusions　Point P3 is the most dangerous zone of the upper boundary of the quadrilateral plate, which is about 27 mm from point P3 to point P1. If the thickness of the thinnest portion of quadrilateral plate is less than 4.47 mm in male or 3.56 mm in female by Mimics measurement, then no screw or short screw with length shorter than 14 mm in male or 12 mm in female is recommended to be inserted at point P3.