Blayney A W, Williams K R, Rice H J
Department of Otolaryngology, Mater Misericordiae Hospital, Dublin, Ireland.
Acta Otolaryngol. 1997 Mar;117(2):269-73. doi: 10.3109/00016489709117785.
This study was undertaken in an attempt to better understand the mechanics of sound transmission at the footplate following stapedotomy. The insertion of a Teflon (polytetrafluoroethylene) stapes prosthesis introduces new constraints within the reconstructed ossicular chain which have an effect on the normal vibration patterns of the tympanic membrane. In a finite element model of the ear, constraints have been reproduced as a series of spring constants in the incus/prosthesis/footplate interfaces incorporating damping to simulate the impedance of the inner ear. At zero damping, the frequency response at the pseudo stapes footplate exhibit several maxima and minima between 800 Hz and 2.5 Hz. At higher damping values, these maxima and minima become smoothened out with two or three naturals occurring over the same frequency range. Severe ankylosis of a diseased footplate is reproduced by over-damped conditions. The umbo, incus and stapes footplate vibrate in phase with similar frequencies at light damping levels. The movement of the prosthesis at the pseudo-footplate can be large in the out of plane axis of the ossicular chain, unless sufficient support is provided at the reconstructed footplate. Clinically, this would suggest the vein graft interposed between the piston and stapedotomy hole should endow resistance and elasticity to the system.
本研究旨在更好地理解镫骨切除术后足板处的声音传播机制。聚四氟乙烯镫骨假体的植入在重建的听骨链中引入了新的限制因素，这对鼓膜的正常振动模式产生影响。在耳的有限元模型中，这些限制因素已被再现为砧骨/假体/足板界面处的一系列弹簧常数，并结合阻尼来模拟内耳的阻抗。在零阻尼时，假镫骨足板处的频率响应在800赫兹至2.5赫兹之间呈现出几个最大值和最小值。在较高的阻尼值下，这些最大值和最小值变得平滑，在相同频率范围内出现两到三个固有频率。通过过阻尼条件再现患病足板的严重强直。在轻度阻尼水平下，鼓膜脐、砧骨和镫骨足板以相似的频率同相振动。除非在重建的足板处提供足够的支撑，否则假体在假足板处沿听骨链平面外轴的移动可能会很大。临床上，这表明置于活塞和镫骨切除孔之间的静脉移植物应为该系统赋予阻力和弹性。
