J Manipulative Physiol Ther. 1995 Jan; 18(1): 4-9.

Forces and relative vertebral movements during SMT to unembalmed post-rigor human cadavers: peculiarities associated with joint cavitation.

GÃ¡l JM, Herzog W, Kawchuk GN, Conway PJ, Zhang YT.

Department of Pure and Applied Biology, University of Leeds, U.K.

OBJECTIVE: The purpose of this study was to compare the relative movements between adjacent vertebrae that were accompanied by a cavitation sound to those relative movements wherein no cavitation sound was recorded, during spinal manipulative treatments (SMTs) to T12 of an unembalmed human cadaver. SETTING: The experiment was conducted in the gross anatomy laboratory at the University of Calgary. SUBJECTS: One 77-yr-old male cadaver was used. INTERVENTIONS: High speed cinematography and embedded bone pin markers were used to record the movements of T10, T11, and T12, during the manipulations. A pressure pad was used to measure the posterior-to-anterior (p-to-a) forces exerted by the clinician onto the cadaver. Two uniaxial accelerometers were used to record the p-to-a accelerations of T11 and T12. The clinician delivered five p-to-a thrusts to the right transverse process of T12. P-to-a forces, p-to-a accelerations, and relative (between T10 and T11, and, T11 and T12) p-to-a translations, lateral translations, and axial rotations, were calculated for each thrust. MAIN RESULTS: A cavitation sound was recorded by the T12 accelerometer during the fourth manipulation. The p-to-a force parameters of the fourth trial were not different from those of the other trials. However, the relative lateral translations between the adjacent vertebrae were substantially greater during the fourth manipulation, compared to the other trials. CONCLUSIONS: The characteristics of the relative lateral translations between adjacent vertebrae suggest that the cavitation sound recorded during the fourth manipulation may have been associated with greater laterally applied forces than those during the other manipulations to T12, wherein no cavitation was recorded.