Biomechanical studies on hip prosthesis stem

利用超声在人工髋关节表面的回波特性，掌握人工髋关节假体假体置入骨内的情况，探讨全髋关节置换术后轻度松动的检测方法。同时，用有限元方法动态分析了窝突之间的接触应力分布情况。研究结果如下：(1)用浸入水箱中的假体柄向股骨发射超声波，测量正常探头到股骨和假体柄交界面的距离。因此，可以精确地获得股骨和骨髓区域的厚度。(2)通过连接在肌肉上的普通探头插入髋关节假体柄，向覆盖着肌肉的股骨发射超声波。从边界表面的回波波形中，精确地获得了股骨、骨髓和肌肉区域的厚度。(3)在(1)和(2)的实验中，人工髋关节柄在股骨内的移动距离可以以0.1 mm的精度测量。(4)利用简单的测量装置可以通过超声波近似测量正常人股骨上侧的截面。(5)股骨的厚度与X射线CT的厚度基本一致。(6)超声法可以测量植入人工髋关节柄的患者股骨内的骨和骨髓厚度。(7)阐明了粘贴在猪股骨上的应变片产生的应变情况。(8)接触应力用有限元方法动态地阐明了窝和髁突之间的分布。

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.