Reliability and validity of a kinematic spine model during active trunk movement in healthy subjects and patients with chronic non-specific low back pain

Abstract

Objective: To develop a standardized, reliable, valid spine model of active trunk movements that accurately discriminates kinematic patterns of patients with chronic non-specific low back pain from those of healthy subjects. Design: Comparative cohort study. Subjects: Healthy subjects (n = 25) and patients with chronic non-specific low back pain (n = 25) aged 30?65 years. Methods: Subjects performed 7 trunk movements from a seated position at non-imposed speed during 2 sessions. Nine markers on bony landmarks measured range of motion and speed of 5 spinal segments, recorded by 8 optoelectronic cameras. Results: Both groups showed good?excellent reliability in all movements for range of motion and speed of all spinal segments (intraclass correlation (ICC), 0. 70?0. 96; standard error of measurement, expressed as a percentage, 19. 4?3. 3%). The minimal detectable change in the patient group was 16. 7?53. 7%. Range of motion and speed in all spinal segments for trunk flexion, rotation, and flexion with rotation differed significantly between groups (p < 0. 001), with large/very large effect sizes (Cohen?s d = 1. 2?2). Binary logistic regression yielded sensitivities/specificities of 92%/84% for range of motion and 92%/80% for speed. Conclusion: Kinematic variables are valid, reliable measures and can be used clinically to diagnose chronic non-specific low back pain, manage treatment, and as quantitative outcome measures for clinical trial interventions.