Pelvic mobility when bending forward in standing position: Validity and reliability of 2 motion analysis devices

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