Analysis of the bending behaviour of the lumbar spine during posteroanterior mobilization

This research study aimed to measure the bending stiffness of the lumbar spine when subjected to posteroanterior mobilization. The lumbar spine was modeled as an initially curved beam column supported over the rib cage and the pelvis. Together with the posteroanterior mobilization force acted on the spine formed the three-point bending of the beam. The bending stiffness of the spine was derived from the mobilization force and the change in curvature of the spine. The mobilization force was measured by mounting a force plate onto the mobilization couch, and electromagnetic sensors were used to measure the change in spinal curvature. The mean bending stiffness of the spine was found to be 38.5 Nm2. The theoretical modelling suggested that the pelvic rotation produced by mobilization may be employed to provide an indicator of the magnitude of the mobilization force.