人工股骨头置换术后假体柄断裂的光弹性研究

PHOTOELASTIC STUDY OF FRACTURE OF PROSTHETIC STEM AFTER FEMORAL HEAD REPLACEMENT/

关节假体柄部断裂在股骨头置换术后并非少见。本实验采用光弹性技术研究模拟人工股骨头假体应力分布，分析人工股骨头假体柄断裂的因素。通过实验研究及８例（９个部位）人工股骨头置换术后假体柄断裂的临床观察，确定其致柄断裂的因素为：①骨水泥的填充和股骨距的截取对假体的应力分布有直接影响；②人工股骨头假体装置不当，如假体内翻或外翻畸形位，均能形成柄部应力集中；③人工股骨头假体一旦出现松动，原装置的假体与股骨上段应力分布发生改变，易导致柄部疲劳断裂。

The fracture of the prosthetic stem after prosthetic replacement of femoral head is not rare. In this study, the photoelastic instrument was used to study the stress distribution on the prosthetic stem following its insertion and to analyse the factors influencing the fracture of the stem. Through the examination of 9 places in 8 cases, it was found that: (1) The removal of femoral calcar and the inframedullary filling of the bone cement directly influenced the stress distribution. (2) The valgus or varus condition of the prosthesis would lead to stress concentration on the stem. (3) Once lossening of the prosthesis occured it would change the preliminary installing stress distribution in the upper femur which would lead to fatigue fracture. This experimental data and clinical observation would provide scientific basis for the prevention of fracture of prosthetic stem following prosthetic replacement of femoral head.