Biomechanical characterization of cervical spinal manipulation in living subjects and cadavers.

Background: Cervical spinal manipulative therapy (cSMT) is a common therapeutic modality used in the treatment of neck pain and headaches. Cadaveric necks have been used as a model for assessing the effects of cSMT on vertebral artery mechanics. However, there have been no previous studies comparing the biomechanical indices of cSMT performed in living subjects versus cadavers.

Methods: The preload force, peak force and duration of cSMT performed by two chiropractors were recorded in 28 subjects with and without neck pain, and in five cadavers.

Results: There were no statistical differences in terms of the preload, peak force and duration of cSMT in living subjects with versus without neck pain. However, all three parameters differed statistically in living subjects versus cadavers; and both preload and peak forces were significantly higher for cadaveric cSMT; the average peak force was 190.3±85.5N (mean±SD) in living subjects, versus 283.9±53.6N in cadavers. Furthermore, the duration was significantly faster for cadaveric cSMT (175±100ms in living subjects versus 120±30ms in cadavers. These observations were consistent for both chiropractors.

Conclusions: When performed in cadavers, cSMT tends to be more "aggressive" in terms of all biomechanical indices used to describe cSMT.