Longitudinal associations of kinematics and fear-avoidance beliefs with disability, work ability and pain intensity in persons with low back pain

Abstract Background Impaired lumbar movement has cross-sectionally been associated with low back pain (LBP); however, the consequence of impaired movement on disability and pain in persons with LBP is poorly understood. Furthermore, fear-avoidance beliefs (FAB) may influence spinal movement, but the relation between fear-avoidance and kinematics is unclear. Objectives To investigate the longitudinal associations of kinematics and FAB with disability, work ability and pain in patients with LBP. Further, to explore associations between FAB and kinematics. Design Prospective observational study. Method Kinematic measures were performed on 44 persons with LBP at baseline, three and nine months. Motion sensors identified range-of-motion and velocity during a spinal flexion/extension. FAB, disability, work ability and pain were reported at all time points using questionnaires. Results Increased range-of-motion was weakly associated with less disability (−0.14 points, 95% CI -0.22 to −0.06). Velocity was not associated with disability, work ability or pain. Higher FAB of physical activity were associated with more disability (1.50 points, 95% CI 0.51 to 2.49) and pain (0.37 points, 95% CI 0.11 to 0.62). Higher work-related FAB was associated with lower work ability (−0.37 points, 95% CI -0.68 to −0.05). Moreover, higher FAB showed weak associations with lower velocity in the initial movement phase (−3.3°/s, 95% CI -6.1 to −0.5). Conclusions Of the kinematic measures, only range-of-motion was related to disability. Higher FAB was weakly associated with all self-reported outcomes and with lower velocity only at the initial flexion phase. However, the magnitude of these associations suggest marginal clinical importance.