Abnormal lumbar movement has been observed in individuals who have a history of low back pain (LBP). Affected individuals display a reduction in lumbar spine rotation during trunk movement tasks, while pelvic rotation increases to compensate. Reduced lumbar contribution to forward bending is associated with increased compressive forces and increased shearing demand of the task on the lower back. This abnormal lumbo-pelvic coordination (LPC) can persist beyond LBP symptom alleviation and may contribute to further occurrences or more severe cases of LBP. This study serves as a first step in investigating if abnormal LPC can be corrected with a hip orthosis by examining the effects of the device on the LPC of healthy individuals. Twenty participants without presence or history of LBP were recruited to participate in a repeated measures study, completing trunk motion tasks with and without a hip orthosis. In a random order, participants completed forward bending and backward return, lateral bending to the left and right, and axial twisting to the left and right. Thoracic, lumbar, and pelvic rotation along with lumbar-thoracic ratio (LTR) were calculated for each of the movement tasks. Thoracic rotation (total trunk movement) was not significantly altered (p > 0.05, F=0.633) by the application of the hip orthosis. LTR was significantly increased (p < 0.001, F=2.96) with the orthosis by 32%, 22%, 12%, 4%, and 12% for axial twisting left, axial twisting right, lateral bending left, lateral bending right, and forward bending, respectively. This indicates lumbar contributions were increased by physically restricting the pelvis. The effects of a hip orthosis should be further investigated in LBP patients to verify correction of an abnormal LPC.

Management and control of the low back pain as an important health problem in the industrial societies necessitates to investigate how the risk of this disease is affected by aging. Since the abnormalities of the lumbopelvic kinematics are related to the existence or risk of low back injuries, the objective of this dissertation was set to find the age-related differences in lumbopelvic kinematics when performing basic trunk motions reaching to range of motion in different anatomical planes. A cross-sectional study was designed where sixty asymptomatic individuals between 20–70 years old with no confounding health condition, no current or previous highly physically demanding occupation and a body mass index between 22 and 30, were divided in five equally-sized and gender-balanced age groups, and attended two sessions of data collection to perform three repetitions of self-selected slow and fast trunk forward bending and backward return, as well as one left and right lateral bending and axial twist. Following an extensive literature review, the lumbar contribution (LC) to the trunk motion, the mean absolute relative phase (MARP) between the thoracic and pelvic motions as well as variation in MARP under repetitive motions, denoted by deviation phase (DP) were selected and used for the assessment of age-related differences in lumbopelvic kinematics during forward bending and backward return tasks. Lumbopelvic kinematics during the lateral bending and axial twist tasks were assessed using the lumbar and pelvic ranges of motion (ROMs) and coupled motion ratios (CMRs) as respectively the maximum flexion/rotation in the primary (i.e., intended) and the secondary (i.e., coupled) planes of trunk motion, where the latter was normalized to the conjugate ROM for better comparison. The results showed age-related differences between the age groups above and under 50 years of age generally. A smaller LC during the forward bending and backward return tasks were observed in the older versus younger age groups, suggesting that the synergy between the active and passive lower back tissues is different between the older and younger people, which may affect the lower back mechanics. Also, smaller MARP and DP suggesting a more in-phase and more stable lumbopelvic rhythm were observed in the older versus younger age groups, which may be a neuromuscular strategy to protect the lower back tissues from excessive strain, in order to reduce the risk of injury. Furthermore, the coupled motion of lumbar spine in the transverse plane during the lateral bending to the left, and the coupled motion of pelvis in the sagittal plane during the axial twist to the right were larger in older versus younger age groups. In summary, the lumbopelvic kinematics changes with aging, especially after the age of 50 which implies alterations in the active and passive tissue responses to the task demands, as well as the neuromuscular control patterns. Drawing a conclusion regarding ii the effect of aging on the risk of low back pain from these results requires a further detailed knowledge on age-related differences in spinal active and passive tissue properties.

Abnormalities in lumbopelvic rhythm (LPR) play a role in occurrence/recurrence of low back pain (LBP). The LPR before spinal fusion surgery and its changes following the surgery are not understood. A repeated measure study was designed to investigate timing and magnitude aspects of LPR in a group of patients (n = 5) with LBP before and after a spinal fusion surgery. Participants completed a forward bending and backward return task at their preferred pace in the sagittal plane. The ranges of thoracic and pelvic rotations and lumbar flexion (as the magnitude aspects of LPR) as well as the mean absolute relative phase (MARP) and deviation phase (DP) between thoracic and pelvic rotations (as the timing aspects) were calculated. Thoracic, pelvic, and lumbar rotations/flexion were respectively 2.19° smaller, 17.69° larger, and 19.85° smaller after the surgery. Also, MARP and DP were smaller during both bending (MARP: 0.0159; DP 0.009) and return (MARP: 0.041; DP: 0.015) phases of the motion after surgery. The alterations in LPR after surgery can be the result of changes in lumbar spine structure due to vertebral fusion and/or new neuromuscular adaptations in response to the changes of lumbar spine structure. The effects of altered LPR on load sharing between passive and active components of lower back tissues and the resultant spinal loads should be further investigated in patients with spinal fusion surgery.