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目的：建立宫骶韧带和主韧带的有限元模型，分析不同工况下宫骶韧带和主韧带的应力分布及变形情况。方法2013年11月至2014年2月在北京大学人民医院选择Ⅲ~Ⅳ度盆腔器官脱垂（POP）患者及健康女性志愿者为观察对象，分为前位子宫组和后位子宫组，选择两例POP患者及两例志愿者分别入组前位子宫组和后位子宫组。对两组妇女进行盆腔MRI扫描，基于MRI原始数据集，应用Mimics、ANSYS等软件构建宫骶韧带和主韧带的有限元模型，仿真计算不同工况下宫骶韧带和主韧带的应力分布及变形情况。结果在各组织弹性模量一定，最大Valsalva动作产生的腹压分别为60、99、168 cmH2O（1 cmH2O=0.098 kPa）的3种不同工况下，根据目前条件及仿真推理，分析得出的趋势为：POP患者和志愿者的子宫、阴道前壁、宫骶韧带和主韧带的应力和变形主要分布于阴道前壁中下段，或者韧带与子宫颈-阴道的连接处，其中最大应力及最大位移均主要集中于阴道前壁下部区域。随最大Valsalva动作所产生腹压的增加，前位子宫组POP患者在3种不同工况下的最大应力值分别为0.0279、0.0460、0.0780 MPa，最大位移值分别为9.1455、15.0900、25.6070 mm，前位子宫组志愿者的最大应力值分别为0.0126、0.0208、0.0353 MPa，最大位移值分别为1.8167、2.9975、5.0867 mm；后位子宫组POP患者在3种不同工况下的最大应力值分别为0.0694、0.1146、0.1945 MPa，最大位移值分别为11.6580、19.2360、32.6430 mm，后位子宫组志愿者最大应力值分别为0.0091、0.0151、0.0256 MPa，最大位移值分别为2.5816、4.2596、7.2284 mm；两组的最大应力值及最大位移值均随腹压的增加而增加，POP患者的最大应力值及最大位移值均大于志愿者；在不同工况下，后位子宫组POP患者的最大应力值及最大位移值均大于前位子宫组POP患者。结论宫骶韧带和主韧带的有限元模型完全基于MRI技术且模型真实可靠。腹压的增高会对宫骶韧带和主韧带产生较大的应力及变形，是造成韧带损伤的原因之一。

Objective To establish the finite element model of uterosacral ligament (USL) and cardinal ligament (CL) and analyze the stress distribution and deformation with USL and CL under different working conditions. Methods Patients with stage Ⅲ-Ⅳpelvic organ prolapse (POP) and healthy female volunteers were selected for research subject, and divided into anterior uterus group and posterior uterus group. Two POP patients and two volunteers were selectd into the anterior uterus group and posterior uterine group respectively. Pelvic MRI scan was performed in two groups. Based on the original MRI data sets, the finite element model of USL and CL was constructed by using the software such as the Mimics, and the stress distribution and deformation of USL and CL were simulated. Results Under the premise of the elastic modulus fixed and three different working conditions such as 60 cmH2O, 99 cmH2O and 168 cmH2O (1 cmH2O=0.098 kPa) with abdominal pressure generated by maximum Valsalva maneuver, according to the present conditions and the simulation, the trend was analyzed: the stress and deformation of the uterus, anterior vaginal wall, USL and CL in two groups were mainly distributed in the middle and lower part of the anterior vaginal wall or the ligament and the cervix-vagina junction, the maximum stress and the maximum displacement were mainly concentrated in the lower region of the anterior vaginal wall. With increasing of abdominal pressure generated by the maximum Valsalva maneuver, the maximum stress values of the POP patient in anterior uterus group under three different working conditions were: 0.027 9, 0.046 0, 0.078 0 MPa, and the maximum displacement values were: 9.145 5, 15.090 0, 25.607 0 mm. The maximum stress values of the volunteer in anterior uterus group under three different working conditions were:0.012 6, 0.020 8, 0.035 3 MPa, and the maximum displacement values were: 1.816 7, 2.997 5, 5.086 7 mm. The maximum stress values of the POP patient in posterior uterine group under three different conditions were: 0.069 4, 0.114 6, 0.194 5 MPa, and the maximum displacement values were:11.658 0, 19.236 0, 32.643 0 mm. The maximum stress values of the volunteer in posterior uterus group under three different working conditions were:0.009 1, 0.015 1, 0.025 6 MPa, and the maximum displacement values were:2.581 6, 4.259 6, 7.228 4 mm. The maximum stress values and the maximum displacement values were all increased with increasing of abdominal pressure in the two groups. The maximum stress values and the maximum displacement values of the POP patients were greater than those of volunteers. Under different working conditions, the maximum stress values and maximum displacement values of the posterior uterus POP patient were all greater than those of the anterior uterus POP patient. Conclusions The finite element model of USL and CL is completely based on the MRI technology and the model is real and reliable. The increase of abdominal pressure will produce a larger stress and deformation of USL and CL, which is one of the reasons causing the injury of the ligament.