Low back pain, defined as pain located between the thoracolumbar junction and the lower gluteal fold, becomes chronic in 8% of patients. As the leading cause of disability worldwide, it has major individual and medico-economic consequences.
Three-dimensional biomechanical analysis allows exploration of movement alterations related to low back pain. Although several parameters have already been studied (maximum joint range of motion (ROM), lumbopelvic rhythm, movement variability, gait), no consistent kinematic profile has emerged. Movement fluidity, assessed by the presence of jerks (brief movement disturbances), remains under-described despite its relevance in evaluating movement quality.
Invistigators hypothesize that lumbar spine movement fluidity during flexion improves after a rehabilitation program and correlates with clinical response.
This project stands out by exploring a rarely studied parameter (movement fluidity) and integrating it as a potential indicator for rehabilitation monitoring.
Age between 18 and 65 years inclusive
BMI between 18-30 kg/m²
Chronic low back pain lasting more than three months
Rehabilitation care in the Physical Medicine and Rehabilitation Department of Montpellier University Hospital
Sciatica episode within the last three months
Traumatic, tumoral, or infectious cause of low back pain
History of spinal, pelvic, or hip fracture
Inflammatory rheumatism
Single group
X-sens sensor
Devicekinematic movement measurement using 5 Xsens inertial sensors (Awinda) placed on the head, thoracic vertebrae (T8), lumbar vertebrae (L1, L4), and sacrum (S1), before and after the rehabilitation program (ten working days). Movement will be measured during standardized tasks including 3 lumbar spine flexions and 3 right and left lumbar rotations. Movements will be recorded by the sensors at a frequency of 100 Hz.
Correlation between the evolution of trunk flexion movement fluidity and the evolution of disability before and after rehabilitation program
Movement velocity will be measured during flexion using Xsens inertial measurement units (head, T8, L1, L4, S1). Velocity profiles will identify acceleration and deceleration phases. Movement fluidity will be quantified by a normalized jerk metric: the count of local minima and maxima on the angular velocity curve divided by flexion/extension duration (peaks/s). This normalization accounts for variations in movement speed between individuals and measurement sessions, providing a standardized measure of movement smoothness where lower values indicate more fluid motion. Disability will be measured by the change in the score of Oswestry Disability Index (ODI) questionary between the first and last day of rehabilitation. The ODI questionary contains ten topics concerning intensity of pain and activities of daily life. Each question is scored on a scale of 0-5 where zero indicates the least amount of disability and 5 indicating most severe disability. The ODI scale range from 0 to 100
Changes in range of motion (ROM) between the first and last day of rehabilitation program
The evolution of trunk range of motion (degree) between the first and last day of rehabilitation will be measured during flexion and rotation movement using Xsens inertial measurement units positioned on the head and at T8, L1, L4 and S1. ROM represents the maximal angular displacement reached by the trunk during the movement and allows identification of the contribution of different segments.
Changes in maximum angular velocity between the first and last day of rehabilitation program
The evolution of maximum angular velocity (degrees per second) between the first and last day of rehabilitation will be measured during flexion and rotation movements using Xsens inertial measurement units positioned on the head and at T8, L1, L4, S1. Angular velocity reflects the peak speed at which the trunk segment rotates during motion. The movement velocity will be assessed both locally and globally.
Changes in lumbopelvic rhythm between the first and last day of rehabilitation program
Changes in lombopelvic rhythm between the first and last day of rehabilitation will be assessed during the flexion using Xsens inertial measurement units positioned on the head and at T8, L1, L4, S1. lombopelvic rhythm represents the coordination and relative contribution of lumbar spine and pelvic motion during bending tasks.
Changes in functional disability between the first and last day of rehabilitation program
The evolution of functional disability between the first and last day of rehabilitation program will be measured by the Oswestry Disability Index (ODI) questionary. This self-completed questionnaire contains ten topics concerning intensity of pain, and activities of daily life. Each topic category contains 6 statements describing a growing degree of relative severity to a particular activity. The patient then checks the statement which most closely resembles their situation. Each question is scored on a scale of 0-5 where zero indicates the least amount of disability and 5 indicating most severe disability. The ODI scale range from 0 to 100 where zero corresponds
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