Lumbopelvic Kinematics in the Primary and Secondary Planes of Motion During Lateral Bending and Axial Twisting: Age-Related Differences

Abstract

OCCUPATIONAL APPLICATIONSTrunk lateral bending and axial twisting are common in the workplace, and are associated with an increase in the risk of low back pain (LBP). We investigated the motions of the lumbar spine and pelvis during these activities, in a laboratory setting, and determined if there are age-related differences. No age-related differences were found in the ranges-of-motion of the lumbar spine or pelvis segment in the primary planes of motion during trunk lateral bending and axial twisting. There were, however, some important differences in coupled motions, outside of the primary planes of trunk motion; where such differences were evident, coupled motions were larger among older individuals. These age-related differences in lumbo-pelvic kinematics, together with earlier evidence of differences in the active and passive mechanical behavior of lower back tissues, imply age-related differences in spinal loads that may contribute to a differential risk of LBP.TECHNICAL ABSTRACT Background: Trunk lateral bending and axial twisting are associated with pelvic and lumbar motions that do not occur solely in the frontal and transverse planes, respectively; rather, there are components (coupled motions) in other anatomical planes. Purpose: We determined if there are age-related differences in the kinematics of the lumbar spine and pelvis in both primary and secondary planes during lateral bending and axial twisting. Methods: Ranges-of-motion (RoMs) in the lumbar spine and pelvis was measured in primary and secondary planes during trunk lateral bending and axial twisting, and compared between 71 participants in five age groups (aged 20–70 years). RoMs in secondary planes was normalized to values in the primary plane, and are reported as coupled motion ratios (CMRs). Results: Lumbar CMR in the transverse plane during lateral bending to left, and pelvic CMR in the sagittal plane during the axial twisting to right, were both significantly larger in older age groups. Additionally, lumbar CMR in the sagittal plane during the lateral bending to left, and pelvic RoM in the frontal plane during the lateral bending to both directions, were both larger among males. Conclusions: The observed age-related differences in lumbo-pelvic kinematics during trunk lateral bending and axial twisting likely impose different levels of risk for low back pain due to excessive spinal loads. The underlying sources of the age-related differences found here, particularly given known age-related differences in the active and passive mechanical behavior of lower back tissues, should be investigated in future work, along with their impacts on spinal loads.