title: Femtosecond laser ablation of bovine cortical bone.
abstract: We study the surface topographical, structural, and compositional modifications induced in bovine cortical bone by femtosecond laser ablation. The tests are performed in air, with a Yb:KYW chirped-pulse-regenerative amplification laser system (500 fs, 1030 nm) at fluences ranging from 0.55 to 2.24 J/cm2. The ablation process is monitored by acoustic emission measurements. The topography of the laser-treated surfaces is studied by scanning electron microscopy, and their constitution is characterized by glancing incidence x-ray diffraction, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and micro-Raman spectroscopy. The results show that femtosecond laser ablation allows removing bone without melting, carbonization, or cracking. The structure and composition of the remaining tissue are essentially preserved, the only constitutional changes observed being a reduction of the organic material content and a partial recrystallization of hydroxyapatite in the most superficial region of samples. The results suggest that, within this fluence range, ablation occurs by a combination of thermal and electrostatic mechanisms, with the first type of mechanism predominating at lower fluences. The associated thermal effects explain the constitutional changes observed. We show that femtosecond lasers are a promising tool for delicate orthopaedic surgeries, where small amounts of bone must be cut with negligible damage, thus minimizing surgical trauma.
authors.affiliation: Technical University of Lisbon, Instituto de Ciência e Engenharia de Materiais e Superfícies, IST, Avenida Rovisco Pais, 1049-001 Lisbon, Portugal.
authors.forename: Liliana T
authors.initials: LT
authors.lastname: Cangueiro
authors.forename: Rui
authors.initials: R
authors.lastname: Vilar
authors.forename: Ana M
authors.initials: AM
authors.lastname: Botelho do Rego
authors.forename: Vania S F
authors.initials: VS
authors.lastname: Muralha
mesh_terms: D000818:Animals; D002417:Cattle; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005269:Femur / Q000601:surgery* / Q000648:ultrastructure*; D066298:In Vitro Techniques; D053685:Laser Therapy / Q000295:instrumentation* / Q000379:methods*; D010027:Osteotomy / Q000295:instrumentation* / Q000379:methods*; D016896:Treatment Outcome