HIGH-POWER HO-YAG LASER-ABLATION OF INTERVERTEBRAL DISKS - EFFECTS ONABLATION RATES AND TEMPERATURE PROFILE

Background and Objective: As the Ho:YAG laser gained increasing import ance in recent experimental and clinical investigations, this study wa s performed to investigate the effect of power on ablation rates and t emperature during disc ablation with a high power Ho:Yag laser under s imulated clinical conditions. Study Design/Materials and Methods: A hi gh power Ho:YAG laser was used to investigate the influence of increas ing power from 10 to 32 Watt on ablation rate (mg) and temperature (de grees C). Ablation weight was measured by a precision scale calculatin g the difference of the pre- and postlasing weight of the specimen aft er application of total energies of 1,000, 1,500, and 2,000 J. Tempera tures were measured by thermoprobes, which were connected via a thermo module to an amplifier and the signal was plotted by a computer with a ppropriate software. Results: Whereas ablation rate rose almost Linear ly 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, wher eas 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 indu ce a rise in temperature. (C) 1995 Wiley-Liss, Inc.