Ablation of Bone without Thermal or Acoustic Injury via a Novel Ultrafast Picosecond Infrared Laser

Abstract

Objectives: A precise method to ablate bone without significant thermal or acoustic injury has remained elusive. A novel non-ionizing ultrafast pulsed picosecond infrared laser (PIRL) may provide the solution. The PIRL ablates tissue through purely photomechanical means, via a thermoelastic front spallation effect, with near complete thermal and acoustic transient confinement. In contrast, the Er:YAG laser ablates tissue via a micro-explosive vaporization mechanism. This study compares PIRL and Er:YAG laser ablation of bone by infrared thermography (IRT), digital microscopy, and electron microscopy. Methods: Ten cuts were made in fresh ex-vivo cortical bone via PIRL and Er:YAG laser ablation under IRT imaging. Lasers were operated using similar average power settings (68 mW) at fluence levels (0.78 J/cm2 and 8.15 J/cm2) in the treatment window above the ablation threshold and below ionization threshold for the PIRL and Er:YAG laser respectively. Digital and electron microscopy were used to image the ablation zones. Results: Peak temperature was negligible and significantly lower for PIRL in comparison to Er:YAG laser ablation (1.56 ± 2.71°C vs. 12.99 ± 2.71°C, P = 0.008). Digital microscopy revealed similar cortical surface ablation volumes for both lasers. Electron microscopy demonstrated well delineated ablation zone margins with no sign of micro-fracture or thermal injury for PIRL ablation. Conclusions: The PIRL provides a means of bone ablation without acoustic shockwave induced micro-fractures or thermal injury. This novel laser has great potential in advancing surgical techniques and outcomes in otologic, neurotologic, implant, cranio-maxillofacial, and head and neck reconstructive surgery.