title: Bone ablation without thermal or acoustic mechanical injury via a novel picosecond infrared laser (PIRL).
abstract: OBJECTIVE
  A precise means to cut bone without significant thermal or mechanical injury has thus far remained elusive. A novel non-ionizing ultrafast pulsed picosecond infrared laser (PIRL) may provide the solution. Tissue ablation with the PIRL occurs via a photothermal process with thermal and stress confinement, resulting in efficient material ejection greatly enhanced through front surface spallation photomechanical effects. By comparison, the Er:YAG laser (EYL) ablates via photothermal and cavitation-induced photomechanical effects without thermal or acoustic confinement, leading to significant collateral tissue injury. This study compared PIRL and EYL bone ablation by infrared thermography (IRT), environmental scanning electron microscopy (ESEM), and histology.
  
  
  METHODS
  Prospective, comparative, ex vivo animal model.
  
  
  METHODS
  Optics laboratory.
  
  
  METHODS
  Ten circular area defects were ablated in ex vivo chicken humeral cortex using PIRL and EYL at similar average power (~70 mW) under IRT. Following fixation, ESEM and undecalcified light microscopy images were obtained and examined for signs of cellular injury.
  
  
  RESULTS
  Peak rise in surface temperature was negligible and lower for PIRL (1.56 °C; 95% CI, 0.762-2.366) compared to EYL ablation (12.99 °C; 95% CI, 12.189-13.792) (P < .001). ESEM and light microscopy demonstrated preserved cortical microstructure following PIRL ablation in contrast to diffuse thermal injury seen with EYL ablation. Microfractures were not observed.
  
  
  CONCLUSIONS
  Ablation of cortical bone using the PIRL generates negligible and significantly less heat than EYL ablation while preserving cortical microstructure. This novel laser has great potential in advancing surgical techniques where precision osseous manipulation is required.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, McGill University, Montreal, Canada.
authors.forename: Nathan
authors.initials: N
authors.lastname: Jowett
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wöllmer
authors.forename: Rudolph
authors.initials: R
authors.lastname: Reimer
authors.forename: Jozef
authors.initials: J
authors.lastname: Zustin
authors.forename: Udo
authors.initials: U
authors.lastname: Schumacher
authors.forename: Paul W
authors.initials: PW
authors.lastname: Wiseman
authors.forename: Alex M
authors.initials: AM
authors.lastname: Mlynarek
authors.forename: Arne
authors.initials: A
authors.lastname: Böttcher
authors.forename: Carsten V
authors.initials: CV
authors.lastname: Dalchow
authors.forename: Balazs B
authors.initials: BB
authors.lastname: Lörincz
authors.forename: Rainald
authors.initials: R
authors.lastname: Knecht
authors.forename: R J Dwayne
authors.initials: RJ
authors.lastname: Miller
mesh_terms: D000818:Animals; D001831:Body Temperature; D002056:Burns / Q000473:pathology / Q000503:physiopathology; D002645:Chickens; D004195:Disease Models, Animal; D005260:Female; D005500:Follow-Up Studies; D006811:Humerus / Q000503:physiopathology / Q000601:surgery* / Q000648:ultrastructure; D053685:Laser Therapy / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D011446:Prospective Studies; D013817:Thermography
keywords: Er:YAG laser; bone ablation; bone cutting; cold ablation; laser ablation; picosecond infrared laser (PIRL); ultrafast laser ablation