Passive intervertebral restraint is different in patients with treatment-resistant chronic nonspecific low back pain: a retrospective cohort study and control comparison.

Abstract

Purpose In vivo studies of continuous lumbar sagittal plane motion have found passive intervertebral motion to be more uneven in patients with chronic nonspecific low back pain (CNSLBP) than healthy controls, but the mechanisms are unclear. This study aimed to compare patients with CNSLBP with a matched group of pain free controls for intervertebral restraint during passive recumbent bending. Methods Seventeen patients with CNSLBP and minimal disc degeneration who had quantitative fluoroscopy investigations were matched to 17 healthy controls from a database acquired using the same imaging protocol. The entire database (n=136) was examined for clustering of peaking times, magnitudes and ROM of first derivatives of the intervertebral angle/motion curves (PTFD, PMFD, ROM) during flexion and return that might introduce confounding. The groups were then compared for differences in these variables. Results There were significant segmental ROM differences among clusters in the database when PMFD and ROM were used as clustering variables, indicating heterogeneity. However, in the patient-control study it was PTFD (velocity) that differentiated the groups. At L5-S1 this was at 10.82% of the motion path compared with 25.06% in the controls (p=0.0002). For L4-5, PTFD was at 23.42% of the motion path in patients and 16.33% in controls (p=0.0694) suggesting a trend towards damping. There were no significant differences for PMFD or ROM. Conclusion Peaking time of passive intervertebral velocity occurs early at L5-S1 in patients with CNSLBP. Future studies should explore relationships with altered disc pressures and biochemistry. Usefulness for monitoring regenerative disc therapies should be considered.