FORCES AND RELATIVE VERTEBRAL MOVEMENTS DURING SMT TO UNEMBALMED POST-RIGOR HUMAN CADAVERS - PECULIARITIES ASSOCIATED WITH JOINT CAVITATION

Objective: The purpose of this study was to compare the relative movem ents between adjacent vertebrae that were accompanied by a cavitation sound to those relative movements wherein no cavitation sound was reco rded, during spinal manipulative treatments (SMTs) to T12 of an unemba lmed 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 an d embedded bone pin markers were used to record the movements of T10, T11, and T12, during the manipulations. A pressure pad was used to mea sure the posterior-to-anterior (p-to-a) forces exerted by the clinicia n onto the cadaver. Two uniaxial accelerometers were used to record th e 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 T1 2) p-to-a translations, lateral translations, and axial rotations, wer e calculated for each thrust. Main Results: A cavitation sound was rec orded by the T12 accelerometer during the fourth manipulation. The p-t o-a force parameters of the fourth trial were not different from those of the other trials. However, the relative lateral translations betwe en the adjacent vertebrae were substantially greater during the fourth manipulation, compared to the other trials. Conclusions: The characte ristics of the relative lateral translations between adjacent vertebra e suggest that the cavitation sound recorded during the fourth manipul ation may have been associated with greater laterally applied forces t han those during the other manipulations to T12, wherein no cavitation was recorded.