Objective: To evaluate the validity and reliability of 2 measurement devices that assess pelvic mobility in persons bending forward while in a standing position.
Design: Validity and reliability studies.
Patients: The validity study included 10 patients (4 men, 6 women) aged 42 (range, 33--51yr). The reliability study included 50 subjects (25 men, 25 women) aged 30 (range, 18--49yr).
Interventions: A 3-dimensional ultrasound motion analyzer (CMS 50) and a spine motion analyzer using potentiometers (Rachimètre).
Methods: Two lateral radiographs of the patients' lumbosacral junction were taken, the first in neutral position, the second in full trunk flexion. Correlations between mobilities assessed by radiographs and both devices were evaluated by Spearman's rank correlation coefficient. Reliability was studied in healthy volunteers using the intraclass coefficient correlation (ICC) and the Bland and Altman plot.
Results: Spearman's coefficient between radiographic measures and the Rachimètre and the CMS 50 evaluations were.89 and.81, respectively. For the Rachimètre, ICC was.65 and increased with a better standardization of the measurement procedures. For the CMS 50, ICC was.85, and the Bland and Altman plot revealed no systematic trend.
Conclusions: The Rachimètre and the CMS 50 have acceptable metric properties. Because few simple clinical measurements are available to evaluate pelvic mobility during trunk flexion in standing position, these 2 devices could be useful in the clinical evaluation of low back pain.