The purpose of this manuscript is to review the work that has been performed on the biomechanics of spinal manipulative treatments (SMT) over the past three years at The University of Calgary. The forces delivered to different segments of the spine during SMT vary considerably, and so do the treatment forces delivered by one chiropractor to different patients. Also, it was found that the speed of force application during SMT facilitates cavitation and is responsible for eliciting an electromyographical (reflex) response of the back musculature.
We also found significant movement of thoracic vertebra T11 relative to thoracic vertebrae T10 and T12 during applications of straight posterior-to-anterior thrusts to the transverse process of T11. The relative movements occurred predominantly in the axial and sagittal rotation directions, and not as expected, in the direction of the primary thrust (posterior to anterior).
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