Reliability of measuring thoracic and lumbar spine mobility with ultrasonic movement analysis

Introduction: Movement analysis with external markers is a non-invasive method used for the study of human movements in sports medicine. The aim of the present study was to assess the reproducibility of ultrasonic movement analysis (Zebris CMS 50) on the kinematics of the thoracic and lumbar spine movements in the sagittal plane. Methods: Thirty subjects performed five repeated trials of trunk movements executed on 2 consecutive days (test-retest). Three positions were studied seated in a standardized position: neutral (vertical trunk), maximal flexion and extension. Eight external ultrasonic markers were placed corresponding to the contours of the spinous processes (T1, T3, T5, T7, T9, T17, L1, L3). Pearson correlations were used to quantitate between trials and test-retest reliability. A MANOVA was applied to the measurements to reveal differences between all trials and test-retest. Results: Repeated measurements of trunk flexion and extension on both days of testing demonstrated good to high reliability (Test I: flex. r = 0.79-0.94, ext. r = 0.72-0.92; p < 0.05, Test II: flex. r = 0.76-0.92, ext. r = 0.77-0.91; p < 0.05). The comparison of the test-retest data on consecutive days showed good reliability for trunk flexion (r = 0.76-0.93, p < 0.05) and extension (r = 0.79-0.91, p < 0.05) in the sagittal plane. The MANOVA revealed no significant differences (p < 0.05) between trials and test-retest. Conclusion: The study reveals high reproducibility of ultrasonic movement analysis. It is concluded that this method is effective in studying functional spine movement made by therapists trained in the correct use of the ultrasonic movement analysis. The method will assist clinicians in the objective evaluation and reassessment of functional human movements.