Ablation rates of human meniscal tissue with the Ho:YAG laser: The effects of varying fluences

To further define the operating parameters for Holmium laser meniscectomy, an in vitro experimental was set up to specifically measure ablation rates and the concomitant thermal injury. Using an experiment set-up with a laser fiber penetrating through meniscal tissue slices, energy levels were varied between 167 and 927 Joules (J)/cm2 per pulse to measure meniscal ablation rates. Following each experiment the adjacent thermal effects were evaluated with hematoxylin and eosin and trichrome staining. The fastest ablation rate was found at 927 J/cm2 per pulse. The increase in ablation rates was directly proportional to the increases in energy levels. Histological examination showed the average lateral thermal change to be 400 to 500 microns, with no demonstrated relation to the pulse level of energy. At these laser parameters the higher levels of energy per pulse showed better ablation of human meniscal tissue without increasing thermal effects in adjacent tissue. Higher energy levels and fluences appeared desirable for more efficient arthroscopic meniscectomy with the Holmium laser.