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Open Access Publications from the University of California

Free electron laser ablation of articular and fibro-cartilage at 2.79, 2.9, 6.1, and 6.45 μm: Mass removal studies

  • Author(s): Youn, JI
  • Peavy, GM
  • Venugopalan, V
  • et al.

Published Web Location Commons Attribution 4.0 International Public License

Background and Objective: The wavelength and tissue-composition dependence of cartilage ablation was examined using selected mid-infrared laser wavelengths. Study Design/Materials and Methods: The mass removal produced by pulsed laser ablation of articular and fibro-cartilage (meniscus) were measured. The wavelengths examined were 2.79, 2.9, 6.1, and 6.45 μm and provided by a free electron laser (FEL) emitting 4 μsecond macropulses consisting of 1-2 picoseconds duration micropulses delivered at 350 picosecond intervals. The measurement of tissue mass removal was conducted using a microbalance during laser ablation. Results: These studies demonstrated that for articular cartilage the highest mass removal was achieved at λ = 6.1 μm followed by, in order, λ = 2.79, 2.9, and 6.45 μm. In comparison, the maximum mass removal for fibro-cartilage was achieved using λ = 6.1 μm radiation with no statistically significant differences in mass removal provided by the other wavelengths. In evaluation of the comparative influence of each wavelength on tissue type, there was no difference in ablation efficiency between articular and fibro-cartilage at λ = 6.1 μm. However, the ablation efficiency of articular cartilage was higher than that of fibro-cartilage at both λ = 2.79 and 2.9 μm. By contrast, λ = 6.45 μm radiation ablated fibro-cartilage more efficiently than articular cartilage at radiant exposures greater than 12 J/cm2. Conclusions: The mass removal of articular and fibrocartilage produced by FEL ablation at selected mid-IR wavelengths was measured as a function of incident radiant exposure. The ablation efficiency was found to depend on both wavelength and tissue type. The 6.1 μm wavelength was found to provide the highest ablation efficiency for both articular and fibro-cartilage. © 2005 Wiley-Liss, Inc.

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