The prevalence and economic impact of acute and chronic back pain (BP) and the understanding that many BP problems have mechanical origins have prompted clinicians and researchers to the search for improved analytic and experimental methods to quantify the biomechanical characteristics of the normal and abnormal human spine. This chapter provides a brief review of the biomechanics of spinal manipulation, which is followed by a detailed summary of the dynamic response of the human spine to the Activator Method of chiropractic posterior anterior (PA) manipulation.
Basic Spine Biomechanics: The spinal column combines an intricate architectural arrangement of bone, muscle, and soft tissue components to form a structure of mechanical as well as physiologic significance. Not only does the spinal column serve to protect the spinal cord but it also transmits, attenuates, and distributes the static (time-invarying) and dynamic (time-varying) forces associated with daily activities. Although the spinal column provides the structures for load transmission and attenuation, the pathways for load transmission and attenuation may be greatly altered during voluntary (postural changes) and involuntary (fatigue) activities, producing unstable and pathologic changes to the kinematic behavior of the spinal column. Segmental instability and pathology of the spine are believed to produce abnormal patterns of motion and forces, which may play a significant role in the etiology of low back pain (LBP).2° The ability to quantify in vivo spine segment motion or kinematics, tog ether with the concomitant forces or kinetics, is therefore, of clinical significance in terms of both diagnosis and treatment of spinal disorders and back pain.
Reference: Keller TS. Engineering – in vivo transient vibration analysis of the normal human spine. Section VIII, Chapter 22, pp 431-450, in Fuhr AW, Green JR, Collaca CJ, Keller TS. Activator Methods Chiropractic Technique textbook, St. Louis: Mosby, 1997.