Background and Objectives:

Little is known  about the dynamics of spinal manipulation and mechanical force manually  assisted short lever adjustments in particular. The purpose of this  study is to quantify the biomechanical response to impulsive loads  applied over the cervical spine. A previous study had enabled us to  quantify the response for the lumbar spine. This would enable the  estimation of the internal motion and loading that occurs due to the  instrument delivered short lever chiropractic adjustment.


An anthropomorphic model of the human  body has been constructed for this study. The Activator Adjusting  Instrument, a product of Activator Methods Inc, (Phoenix, AZ), is used  to produce the impulsive loads. The elements of the model involve bones,  ligaments, intervertebral discs and muscles which are constructed from  composite materials that closely mimic the passive properties of the  physiological systems. The instrumentation includes displacement,  acceleration and pressure transducers. The sampling rate of the data was  1,o00 Hz and filtering of the data is done using software.


The anthropomorphic model has been  used in a previous study to study the dynamics of spinal manipulation in  the lumbar spine. It has been found to be a reasonable substitute for  the human spine, in terms of the mechanical responses to forces and/or  torques. The present study involved data collection in the cervical  spine at the levels of C1, C2, C5 and C6. Preliminary data analysis has  been done and the movement response to applied thrusts on the spine has  been done qualitatively and a quantitative analysis is expected to be  done on data in the near future.


Anthropomorphic modeling may prove useful  in understanding the dynamics of spinal manipulation, particularly when  integrated with computer modeling and in vivo studies. Acknowledgement: This study was funded by the National Institute of Chiropractic Research.

Reference: Sridhar Venkataraman, BS, Gary T. Yamaguchi,  PhD, Paul J. Osterbauer, OG, and Arlan W. Fuhr .DC, Arizona State  University, Tempe. AZ, The National Institute of Chiropractic Research,  Phoenix. AZ; Evaluating Mechanical Force Manually Assisted Short Lever  adjusting using an Anthropomorphic model; In: The proceedings of the  FCER’s 1993 International Conference on Spinal Manipulation, Montreal,  Quebec, Canada, April 30-May 1, Page 13.