Interaction of holmium laser radiation and cortical bone: ablation and thermal damage in a turbid medium

The ablation of cortical bone by holmium laser radiation is described by experimental values of the ablation rate, the depth of tissue damage, and the tissue temperature. An ablation model is presented on the basis of photon diffusion in a turbid medium. When this model is compared with experimental results for the ablation rate, the penetration depth is determined. The expansion of the laser-induced heat can be explained by a point heat source located in a distance beneath the surface equal to the ablation depth. The accumulation of heat as a function of the repetition rate of the laser leads to a limitation of the repetition rate. In order to avoid traumatic heat accumulation, a maximum repetition rate should not be exceeded.