J Manipulative Physiol Ther. 1997 Jan; 20(1): 30-40.

Movements of vertebrae during manipulative thrusts to unembalmed human cadavers.

GÃ¡l J, Herzog W, Kawchuk G, Conway PJ, Zhang YT.

Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Alberta, Canada.

OBJECTIVE: The purpose of this study was to measure the relative movements of vertebrae during manipulative thrusts to unembalmed post-rigor mortis human cadavers. SETTING: The investigation was conducted in the gross anatomy laboratory at the University of Calgary. SUBJECTS: Two 77-yr-old, unembalmed, post-rigor mortis, male cadavers were used. INTERVENTIONS: The movements of vertebrae were investigated by using high-speed cinematography to record the movements of bone pins threaded into T10, T11 and T12 during spinal manipulative therapy to unembalmed post-rigor human cadavers. A single clinician delivered a series of posterior-to-anterior (p-to-a) thrusts to the right transverse process of either T10, T11 or T12, using a reinforced hypothenar contact. Relative p-to-a and lateral translations, as well as axial and sagittal rotations, in T10-T11 and T11-T12 were calculated. Corresponding p-to-a forces exerted by the clinician onto the cadaver were recorded using a pressure pad. MAIN RESULTS: Significant relative movements were measured primarily between the targeted and immediately adjacent vertebrae during the thrusts. Vertebral pairs remained slightly 'hyper-extended' after the rapid thrusts to T11, when the p-to-a forces returned to preload levels. CONCLUSIONS: These findings may be useful for the understanding of the deformation behavior of the vertebral column during therapeutic manipulation. A fully three-dimensional analysis of all six degrees of freedom, using a larger number of unembalmed cadavers, would be useful in clarifying the relationship between the externally applied forces and the observed relative movement patterns of the vertebrae.