Morita M, Sasada T, Hayashi H, Tsukamoto Y
Department of Bioengineering, School of Medicine, Kitasato University, Kanagawa, Japan.
J Biomed Mater Res. 1988 Jun;22(6):529-40. doi: 10.1002/jbm.820220608.
Fatigue fracture of artificial implants in the human body, caused by the repeated application of stress, is well documented. It is known that the fatigue strength of implant materials decreases when they are exposed under in vivo corrosion conditions. There are, however, no investigations concerning the effect of body fluids on the fatigue characteristics of commonly used biomaterials. Accordingly, fatigue tests on machined stainless-steel AISI 316, and COP alloy rods have been conducted in the right lower leg of rabbit. These specimens were pierced through the hole drilled at the middle of the tibial bone. A cyclic tensile stress of frequency 5 or 10 Hz was applied to the rods. From the results, it was found that the fatigue strength at 5 x 10(6) cycles for AISI 316 under the in vivo environment was 680 MPa compared to 830 MPa in air and similarly for COP alloy, was 680 MPa in the living body compared to 800 MPa in air. These remarkable changes in fatigue strength associated with the in vivo environments are considered to be due to the corrosive action of body fluids on the biomaterials.
人体中人工植入物因反复承受应力而导致的疲劳断裂已有充分记录。已知植入材料在体内腐蚀条件下暴露时，其疲劳强度会降低。然而，尚无关于体液对常用生物材料疲劳特性影响的研究。因此，已在兔的右小腿对加工后的AISI 316不锈钢和COP合金棒进行了疲劳试验。这些试样穿过在胫骨中部钻出的孔。对棒施加频率为5或10 Hz的循环拉伸应力。从结果发现，在体内环境下，AISI 316在5×10⁶次循环时的疲劳强度为680 MPa，而在空气中为830 MPa；同样，COP合金在活体中的疲劳强度为680 MPa，在空气中为800 MPa。与体内环境相关的疲劳强度的这些显著变化被认为是由于体液对生物材料的腐蚀作用。
