组配式人工半骨盆假体置换术后骨盆静态生物力学三维有限元分析

Finite Element Analysis and Static Biomechanics of Pelvic after Modular Hemipelvic Prosthesis Reconstruction

目的研究分析正常骨盆及术后重建骨盆健侧与组配式人工半骨盆假体在不同体位下应力分布情况,从静态生物力学角度为组配式人工半骨盆假体置换术的合理性及安全性提供依据。方法采用CT薄层扫描采集原始数据,分别建立正常骨盆和组配式人工半骨盆假体置换术后骨盆及假体的三维有限元模型,并分别在双脚站立、患侧单脚站立及坐位3种静力状态下进行生物力学加载,分析正常骨盆及术后骨盆和假体在不同体位下应力分布情况。结果在正常骨盆和重建后骨盆两种模型中,不同体位相同载荷下健侧骨盆应力值相差不大,在骶骨正中面上部、骶髂关节、坐骨大切迹上缘骨皮质及坐骨结节处达到最大值,其应力最大值远小于健侧骨盆的疲劳强度;患侧组配式半骨盆假体不同体位时应力最大值均出现在髋臼杯上方CS内固定器与髋臼杯连接部内侧,所受最大应力均远低于其疲劳强度;组配式半骨盆假体重建后骨盆不同体位时应力的分布规律与正常骨盆基本一致。结论组配式人工半骨盆假体置换术对健侧骨盆影响较小;静态不同体位下健侧半骨盆及组配式人工半骨盆假体的最大应力值均明显小于各自的的疲劳强度,健侧骨盆和组配式人工半骨盆假体安全性好;采用组配式人工半骨盆假体重建后的骨盆符合人体正常生物力学规律。

Objective To compare the stress distribution of normal pelvis with those of postoperative contralateral pelvic and modular hemipelvic prosthesis under different positions,with an aim to providing biomechanical evidence support for safe reconstruction of pelvic ring using modular hemipelvic prosthesis.Methods Three-dimensional finite element models of normal pelvis,postoperative pelvic and modular hemipelvic prosthesis were established using thin-layer CT scanning（TLCS）.The stress distributions of normal pelvis,postoperative pelvic and prosthesis were measured under three static positions： standing on two feet,standing on one foot on the defective side and sitting.Results Little difference was found in contralateral pelvic stress between the normal pelvic and reconstructive pelvic models given the same load with different positions.The maximum stress level appeared at the upside of sacrum mesion,sacroiliac joints,superior greater sciatic notch and ischial tuberosity,albeit a much lower level than fatigue strength.The maximum stress level of modular hemipelvic prosthesis appeared at the inner wall of connector bar between CS fixation and acetabular cup.Similarly,the stress level was also much lower than the fatigue strength of connector bar.The stress distribution of postoperative pelvic was similar to that of normal pelvic.Conclusion Reconstruction with modular hemipelvic prosthesis has little effect on contralateral pelvic.The maximum stress levels of contralateral pelvis and modular hemipelvic prosthesis are significantly lower than their fatigue strength,which indicates sound safety of contralateral pelvis and modular hemipelvic prosthesis.Pelvic reconstruction with modular hemipelvic prosthesis produces good biomechanical compatibility.