Ultrafast laser ablation and machining large-size structures on porcine bone

Abstract

Abstract. When using ultrafast laser ablation in some orthopedic applications where precise cutting/drilling is required with minimal damage to collateral tissue, it is challenging to produce large-sized and deep holes using a tightly focused laser beam. The feasibility of producing deep, millimetersize structures under different ablation strategies is investigated. X-ray computed microtomography was employed to analyze the morphology of these structures. Our results demonstrated the feasibility of producing holes with sizes required in clinical applications using concentric and helical ablation protocols.

Influence of environmental conditions in bovine bone ablation by ultrafast laser

“…The ablation experiments were performed using an ultrafast laser machining setup shown in Figure A. A detailed description of the setup can be found in our previous work . Briefly, femtosecond laser pulses (210 fs/FWHM, 200 μJ, 1 kHz, 800 nm) from an amplified Ti: Sapphire system (Tsunami‐Spitfire; Spectra Physics, Santa Clara, California) is used.…”

“…Thus, the increase of ablation rate (the volume of hard tissue removed by the laser per unit time, mm 3 /s) can be achieved by applying high laser fluence. We have demonstrated producing large‐diameter (mm diameter) holes on the cortical bone with the high fluence of laser set to 19.3 J/cm 2 (approximately six times higher than the threshold F th ) . Further increasing the fluence leads to shallower hole depth due to debris deposited on the bottom of the holes .…”

“…We have demonstrated producing large‐diameter (mm diameter) holes on the cortical bone with the high fluence of laser set to 19.3 J/cm 2 (approximately six times higher than the threshold F th ) . Further increasing the fluence leads to shallower hole depth due to debris deposited on the bottom of the holes . There are also concerns that high fluence may also lead to thermal damages to the crater.…”

“…Nonetheless, ultrafast lasers can remove only small amounts of hard tissue within the focal volume, which is on the order of a few micrometers per pulse . Limited by current laser technology, the repetition rate of ultrafast laser ablation is also low, leading to longer time needed to produce large size structures . Therefore, ultrafast lasers are generally more suitable for clinical applications where high precision control is needed, for example, pedicle screw placement in spinal surgery .…”

“…Limited by current laser technology, the repetition rate of ultrafast laser ablation is also low, leading to longer time needed to produce large size structures . Therefore, ultrafast lasers are generally more suitable for clinical applications where high precision control is needed, for example, pedicle screw placement in spinal surgery . Nonetheless, in many hard tissue applications, the formation of deep incisions (few millimeters) into the tissue is required.…”