Résumé
Chronic low back pain is a multifactorial pathology involving psychosocial as well as mechanical factors. Studies suggest the value of a more comprehensive evaluation of these mechanical factors. The objective of our work is to describe the kinematic parameters of the spine in chronic low back pain patients in an ecological situation and to analyse them before/after rehabilitation. Methods: exploratory study comparing 17 patients with chronic low back pain matched with healthy subjects. Kinematic measurements using inertial sensors: XSENS, which make it possible to estimate the orientation, speed and acceleration of body segments during 7 movements. 3 biomarkers were specifically analysed at the level of the thorax and pelvis. Other measurements were taken to estimate the percentage of contact absorption of the lower limbs, pelvis and spine. These assessments were carried out before and after a multimodal rehabilitation programme for the low back pain population. Results: the characteristics of our population were as follows: low back pain evolving for 14 years [0.5-30], age 44 years [32-65], BMI 23 [20-30]. In comparison to healthy subjects, we found in subjects with low back pain a decrease in maximum lumbar amplitude, maximum speed and fluidity. A ‘blocked’ motor behaviour with alteration of the thoraco-pelvic mobility rhythm was identified. When walking, ground contact was weaker and absorption decreased in patients with low back pain. Comparison before and after a rehabilitation programme shows an improvement in these biomarkers. Discussion: we were able to identify a disturbed kinematic signature in subjects with chronic low back pain. Two weeks of outpatient rehabilitation partially restores certain parameters. The interaction between psychosocial and mechanical factors accounts for the very varied phenotypes of the low back pain population. A better understanding of this interaction through reliable kinematic measurements could make it possible to better describe patient profiles, identify early factors of response to rehabilitation, and target our care.