Bending stiffness of the lumbar spine subjected to posteroanterior manipulative force

Abstract

Abstract-This study measured the bending stiffness of the spine when it is subjected to posteroanterior mobilization force. The lumbar spine was modeled as an initially curved beam column supported over the rib cage and the pelvis. Posteroanterior mobilization was assumed to be three-point bending of the beam. The mobilization force was measured by the mounting of a force plate onto the manipulation couch, where electromagnetic sensors measured the change in spinal curvature. The bending stiffness of the spine was derived from the force and curvature data. The technique developed in this study provided highly repeatable data. The theoretical analysis suggests that the pelvic rotation produced by mobilization may be used clinically to indicate the magnitude of the mobilization force. Future research may employ the present method to determine how back pain may affect the bending stiffness of the spine. The bending stiffness values reported in this study will be valuable to future modeling work.

A structured review of spinal stiffness as a kinesiological outcome of manipulation: Its measurement and utility in diagnosis, prognosis and treatment decision-making

“…Asymptomatic: n = 21 Stiffness differs between different levels (lowest at L1, highest at L4) Lee et al (2005) Lumbar: manual oscillating PA pressures applied to L4 with plinth on forceplate and Fastrack motion tracking Asymptomatic: n = 20 Method was reliable over 3 repeated measurements (ICC 0.98) Maher et al (1999) Thoracic and lumbar: mechanical oscillating PA pressures to T6, T12 and L3…”

Changes in Bending Stiffness and Lumbar Spine Range of Movement Following Lumbar Mobilization and Manipulation

“…[14][15][16] However, it has been argued that because the geometry of the lumbar spine is curved and undergoes further deformation of the curve in response to PA loading, it is more appropriate to model bending stiffness through the measurement of curvature change. 13,17,18 This method of measurement has been shown to be highly reliable with correlation coefficients between 0.97 and 0.99, 17 and the differences in these modeling methods may explain the inconsistencies reported in the literature.…”

“…Spinal bending stiffness may be calculated from the relationship between force and displacement. 17 Custom-made devices using a load cell and linear potentiometer to measure PA load and resultant linear displacement were used in some of the studies. [14][15][16] However, it has been argued that because the geometry of the lumbar spine is curved and undergoes further deformation of the curve in response to PA loading, it is more appropriate to model bending stiffness through the measurement of curvature change.…”

A Model for Standardizing Manipulation Terminology in Physical Therapy Practice

“…Third, the ability to apply a manipulation to a highly localized, discreet region remains a matter of debate [44][45][46][47][48][49][50][51][52] . A framework for describing the technique is necessarily limited to describing where and how the force was directed.…”