title: Automated Bone Screw Tightening to Adaptive Levels of Stripping Torque.
abstract: OBJECTIVE
  To use relationships between tightening parameters, related to bone quality, to develop an automated system that determines and controls the level of screw tightening.
  
  
  METHODS
  An algorithm relating current at head contact (IHC) to current at construct failure (Imax) was developed. The algorithm was used to trigger cessation of screw insertion at a predefined tightening level, in real time, between head contact and maximum current. The ability of the device to stop at the predefined level was assessed.
  
  
  RESULTS
  The mean (±SD) current at which screw insertion ceased was calculated to be [51.47 ± 9.75% × (Imax - IHC)] + IHC, with no premature bone failures.
  
  
  CONCLUSIONS
  A smart screwdriver was developed that uses the current from the motor driving the screw to predict the current at which the screw will strip the bone threads. The device was implemented and was able to achieve motor shut-off and cease tightening at a predefined threshold, with no premature bone failures.
authors.affiliation: Medical Device Research Institute, School of Computer Science, Engineering and Mathematics, Flinders University, Adelaide, Australia.
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Reynolds
authors.forename: Aaron A
authors.initials: AA
authors.lastname: Mohtar
authors.forename: Tammy M
authors.initials: TM
authors.lastname: Cleek
authors.forename: Melissa K
authors.initials: MK
authors.lastname: Ryan
authors.forename: Trevor C
authors.initials: TC
authors.lastname: Hearn
mesh_terms: D000465:Algorithms; D000818:Animals; D001863:Bone Screws; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005246:Feedback; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D017276:Friction; D066298:In Vitro Techniques; D008159:Lumbar Vertebrae / Q000503:physiopathology / Q000601:surgery*; D011475:Prosthesis Failure; D065287:Robotic Surgical Procedures / Q000295:instrumentation* / Q000379:methods*; D012756:Sheep; D019415:Torque