Gerber B E, Asshauer T, Delacrétaz G, Jansen T, Oberthür T
Orthopädische Klinik Neuchâtel, Stadtspital Pourtalès.
Orthopade. 1996 Feb;25(1):21-9.
The in vitro study presented helps to clarify the biophysical mechanisms and tissue interactions of the holmium laser at the point of impact on the surface of cartilage-bone specimens investigated in different experimental settings. A striking event is the creation of a vapor bubble that opens up access for the laser beam through the fluid medium. This bubble shows a reproducible dynamic behavior function of the laser irradiance and the angle of incidence of the delivery fiber. These determine directly the amplitude of the pressure waves induced when the bubble collapses. Apart from this acoustic effect, which is correlated with epicentric histological features that can hardly be considered biologically relevant, a thermal effect is recognized that is finally responsible for the ablation and tissue damage. It induces typical histological alterations that can be observed along the laser beam axis, with a penetration function mainly of the irradiance but also of the angle of incidence. Nevertheless, at a pulse energy of 1 J and an irradiation angle of 30 degrees, the recorded overall depth of the immediate histological changes was down to 500-600 micrometers. Thus, in realistic working conditions, the damage observed after cartilage sealing with the holmium laser remains within an absolutely acceptable range. This is in agreement with the better results compared to mechanical cartilage debridement that have been reported in previous prospective clinical studies.
所呈现的体外研究有助于阐明钬激光在不同实验环境下对软骨-骨标本表面撞击点处的生物物理机制和组织相互作用。一个显著的现象是形成了一个蒸汽泡，它为激光束通过流体介质开辟了通道。这个气泡呈现出可重复的动态行为，它是激光辐照度和传输光纤入射角的函数。这些因素直接决定了气泡坍塌时所引发的压力波的振幅。除了这种与难以被视为具有生物学相关性的震中组织学特征相关的声学效应外，还认识到一种热效应，它最终导致了消融和组织损伤。这种热效应会引发典型的组织学改变，这些改变可沿激光束轴观察到，其穿透作用主要取决于辐照度，也与入射角有关。然而，在脉冲能量为1焦耳、照射角度为30度时，所记录的即时组织学变化的总深度低至500 - 600微米。因此，在实际工作条件下，用钬激光封闭软骨后观察到的损伤仍在完全可接受的范围内。这与先前前瞻性临床研究中报道的与机械性软骨清创术相比更好的结果是一致的。
