title: Comparison of mechanical force of manually assisted chiropractic adjusting instruments.
abstract: OBJECTIVE
  To quantify the force-time and force-delivery characteristics of six commonly used handheld chiropractic adjusting devices.
  
  
  METHODS
  Four spring-loaded instruments, the Activator Adjusting Instrument; Activator II Adjusting Instrument, Activator III Adjusting Instrument, and Activator IV Adjusting Instrument, and two electromechanical devices, the Harrison Handheld Adjusting Instrument and Neuromechanical Impulse Adjusting Instrument, were applied to a dynamic load cell. A total of 10 force-time histories were obtained at each of three force excursion settings (minimum to maximum) for each of the six adjusting instruments at preload of approximately 20 N.
  
  
  RESULTS
  The minimum-to-maximum force excursion settings for the spring-loaded mechanical adjusting instruments produced similar minimum-to-maximum peak forces that were not appreciably different for most excursion settings. The electromechanical adjusting instruments produced short duration ( approximately 2-4 ms), with more linear minimum-to-maximum peak forces. The force-time profile of the electromechanical devices resulted in a more uniform and greater energy dynamic frequency response in comparison to the spring-loaded mechanical adjusting instruments.
  
  
  CONCLUSIONS
  The handheld, electromechanical instruments produced substantially larger peak forces and ranges of forces in comparison to the handheld, spring-loaded mechanical devices. The electromechanical instruments produced greater dynamic frequency area ratios than their mechanical counterparts. Knowledge of the force-time history and force-frequency response characteristics of spinal manipulative instruments may provide basic benchmarks and may assist in understanding mechanical responses in the clinical setting.
authors.affiliation: Neuromechanical Innovations, L.L.C, USA. cjcolloca@neuromechanical.com
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Colloca
authors.forename: Tony S
authors.initials: TS
authors.lastname: Keller
authors.forename: Pierre
authors.initials: P
authors.lastname: Black
authors.forename: Martin C
authors.initials: MC
authors.lastname: Normand
authors.forename: Deed E
authors.initials: DE
authors.lastname: Harrison
authors.forename: Donald D
authors.initials: DD
authors.lastname: Harrison
mesh_terms: D019985:Benchmarking; D001696:Biomechanical Phenomena; D004581:Electronics; D004867:Equipment Design; D006801:Humans; D026882:Manipulation, Chiropractic / Q000295:instrumentation* / Q000379:methods*; D019563:Mechanics; D013997:Time Factors