Background and Purpose: The majority of non-specific low back pain is presumed to be mechanical in origin. Many interventions, including manipulation, mobilisation, core strengthening and rigid/motion preserving surgery rely on the premise that intervertebral motion is related to pain in some patients, however, there is no reliable in vivo experimental evidence for this. We compared continuous intervertebral motion from quantitative digital fluoroscopic sequences in asymptomatic controls and patients with chronic non-specific low back pain to investigate associations between pain and intervertebral motion.

Methods: Thirty asymptomatic volunteers and 21 patients with chronic non-specific low back pain underwent passive, controlled, recumbent lateral bending motion during video-fluoroscopic screening. These provided 90 and 44 intervertebral levels from L2-L5 respectively for analysis. Vertebrae were registered digitally and automatically tracked throughout the motion. Inter-vertebral rotation phenotypes for each left-right sequence were obtained and analysed for stiffness (inter-vertebral motion of less than 3o), lax appearance and paradoxical motion. A similar population underwent sEMG studies to determine if muscle activity was present during controlled passive recumbent motion. Associations between pain and stiffness, lax appearance and paradoxical motion were calculated from chi-squared distributions. A subset of patients also had MR scans to assess disc degeneration.

Conclusion: Stiffness was observed significantly more frequently in patients with pain, as was paradoxical motion and lax appearance. sEMG activity was very small throughout motion in both groups. MR degeneration was not associated with stiffness in patients. Results must, however, be regarded as preliminary as greater normative referencing, group matching, more extensive kinematic analysis, flexion-extension, weight-bearing, and clinical outcomes studies are needed.