High power Ho:YAG laser ablation of intervertebral discs: Effects on ablation rates and temperature profile

BACKGROUND AND OBJECTIVE: As the Ho:YAG laser gained increasing importance in recent experimental and clinical investigations, this study was performed to investigate the effect of power on ablation rates and temperature during disc ablation with a high power Ho:Yag laser under simulated clinical conditions. STUDY DESIGN/MATERIALS AND METHODS: A high power Ho:YAG laser was used to investigate the influence of increasing power from 10 to 32 Watt on ablation rate (mg) and temperature (degree C). Ablation weight was measured by a precision scale calculating the difference of the pre- and postlasing weight of the specimen after application of total energies of 1,000, 1,500, and 2,000 J. Temperatures were measured by thermoprobes, which were connected via a thermomodule to an amplifier and the signal was plotted by a computer with appropriate software. RESULTS: Whereas ablation rate rose almost linearly with total energy, increasing power above 20 W did not essentially improve ablation rate. Temperatures reached their highest values after application of a total energy of 500 J and did not rise further, whereas increasing power did not induce a rise in temperature. CONCLUSIONS: Regarding the chosen experimental setting, maximum temperatures are reached after application of 500 J, and increasing power does not induce a rise in temperature.