Biomechanical studies on hip prosthesis stem

利用超声波在骨表面的回波特性，掌握植入人工髋关节假体柄的骨内情况，探讨全髋关节置换术后微松动的检测方法。并通过有限元方法动态分析了髁突与关节窝之间的接触应力分布。结果如下所示。(1)用浸没在水箱中的髋关节假体柄向股骨发射超声波，测量从正常探头到股骨和髋关节假体柄的骨表面的距离。从而精确地获得股骨和骨髓区域的厚度。(2)通过将髋关节假体柄经由附接到肌肉的正常探头插入，向覆盖有肌肉的股骨发射超声波。从边界面的回波波形中，可以精确地获得股骨、骨髓和肌肉区域的厚度。(3)在（1）和（2）的实验中，可以以0.1mm的精度测量髋关节假体柄在股骨内的移动距离。(4)利用简单的测量装置通过超声波可以近似测量正常人股骨上侧的截面。(5)股骨厚度与X线CT结果基本一致。(6)超声方法可以测量插入髋关节假体柄的患者股骨内的骨和骨髓的厚度。(7)阐明了粘贴在猪股骨上的应变片的应变条件。(8)用有限元法动态分析了髁突与关节窝之间的接触应力分布。

The condition inside the bone inserted with a hip prosthesis stem was grasped by utilizing an echo characteristic from a boudary surface via ultrasonic waves, and the mensurement method for detecting a slight loosenig after the total hip replacement was investigated. Also, contact stress distribution between socket and condyle was clarified dynamically by the finite element method. The following results are shown below.(1) The ultrasonic wave was emitted toward the femur with a hip prosthesis stem, which was immersed in a water tank, and the distances from a normal probe to the boudary surfaces of the femur and the hip prosthesis stem were measured. consequently, the thicknesses of the femur and bone marrow regions are obtained precisely.(2) The ultrasonic wave was emitted toward the femur covered with flesh by inserting a hip prosthesis stem via a normal probe attached to the flesh. From the echo waveform from the boundary surfaces, the thicknesses of the femur, bone marrow and flesh regions are obtained precisely.(3) In the experiment of (1) and (2), the moving distance of the hip prosthesis stem inside the femur can be measured with 0.1mm accuracy.(4) The section of the upper side of the normal human femur can be measured approximately using the simple measurement device via the ultrasonic wave.(5) The thickness of femur agrees approximately with that of the X-ray CT.(6) The ultrasonic method can measure the thicknesses of the bone and the bone marrow within the femur on the patient inserted with the hip prosthesis stem.(7) The strain conditions occurring to strain gauges bonded to a pig femur are clarified.(8) The contact stress distribution between socket and condyle is clarified dynamically by the finite eliment method.